Hemophilia
Clinical Snapshot
Hemophilia is an inherited deficiency of a specific clotting factor caused by a pathogenic variant in the F8 gene (hemophilia A, factor VIII deficiency) or the F9 gene (hemophilia B, factor IX deficiency), both located on the X chromosome. Inheritance is X-linked recessive: the disease almost exclusively affects males, who inherit a single affected X chromosome from a carrier mother, while females — who have 2 X chromosomes — are generally considered carriers rather than affected, though a meaningful proportion of carriers do experience clinically significant bleeding themselves (see Special Populations).[1]
Hemophilia A is far more common than hemophilia B, accounting for roughly 80-85% of all hemophilia cases against 15-20% for hemophilia B; estimated live-birth prevalence is approximately 17.1 cases per 100,000 males for all severities of hemophilia A (about 6.0 cases per 100,000 for severe hemophilia A specifically) and approximately 3.8 cases per 100,000 males for all severities of hemophilia B (about 1.1 cases per 100,000 for severe hemophilia B).[1] Both genes are prone to spontaneous new mutations — roughly 30% of all cases arise de novo, and more than half of people newly diagnosed with severe hemophilia have no prior family history, so an absent family history should never be used to argue against the diagnosis.[1]
Severity is classified by residual clotting factor activity level, and this classification correlates strongly with bleeding phenotype — it is one of the genuinely load-bearing frameworks in this chapter, because it directly predicts bleeding pattern and drives the treatment-intensity decisions in Choose Initial Treatment:
| Severity | Factor activity level | Typical bleeding pattern |
|---|---|---|
| Severe | Under 1 IU/dL (under 1% of normal) | Spontaneous bleeding into joints or muscles, predominantly without an identifiable trigger |
| Moderate | 1-5 IU/dL (1-5% of normal) | Occasional spontaneous bleeding; prolonged bleeding with minor trauma or surgery |
| Mild | 5 to under 40 IU/dL (5% to under 40% of normal) | Severe bleeding only with major trauma or surgery; spontaneous bleeding is rare |
Most people with severe hemophilia bleed predominantly into joints and muscles; life-threatening bleeding — intracranial, neck/throat, or gastrointestinal — is far less common but is a true emergency wherever it occurs (see Red Flags & Refer).[1]
Recognize the Condition
Hemarthrosis — the classic and most functionally significant presentation
Joint bleeding (hemarthrosis) accounts for roughly 70-80% of all bleeding episodes in hemophilia and is the presentation with the greatest long-term functional consequence. It occurs disproportionately in the hinged joints — ankles, knees, and elbows — and less often in multi-axial joints such as shoulders and hips.[1] An acute joint bleed typically produces a prodromal tingling or "aura" sensation the patient often recognizes before objective swelling appears, followed by pain, warmth, swelling, and reduced range of motion; prompt recognition and treatment materially reduce the eventual joint damage (see Complications, in Red Flags & Refer, and Non-Pharmacologic Treatment for the PRICE first-aid principles).[1] In infants and very young children who cannot describe pain, a reluctance to use a limb, or unexplained fussiness with movement of a joint, should be treated as a possible bleed rather than dismissed.[1]
Muscle bleeding
Muscle bleeds account for roughly 10-20% of bleeding episodes and are of particular concern in deep compartments — the iliopsoas, calf, and forearm — where swelling can cause compartment syndrome or nerve compression (a femoral neuropathy from an iliopsoas bleed is a classic, easily-missed presentation) well before it is visually obvious.[1]
Severity-dependent bleeding pattern
The severity classification in the Clinical Snapshot table directly predicts what a patient's bleeding will look like: severe hemophilia (factor activity under 1%) most commonly produces spontaneous bleeding into joints, muscles, and occasionally internal organs, often without any identifiable trauma — early, unexplained joint bleeding in a very young child is itself a key clinical indicator of severe disease and should prompt urgent factor assay testing.[1] Moderate hemophilia produces occasional spontaneous bleeding, with prolonged bleeding after minor trauma or surgery. Mild hemophilia may produce no abnormal bleeding at all until the patient experiences serious trauma or undergoes surgery — mild disease is easy to miss because the history can otherwise look unremarkable.[1]
Life-threatening bleeding sites
A smaller but critical category of bleeding sites is life-threatening rather than merely serious: intracranial hemorrhage, neck/throat bleeding (airway risk), and gastrointestinal bleeding. These need emergency recognition and treatment distinct from routine joint/muscle bleed management (see Red Flags & Refer).[1]
Excessive bleeding with trauma or surgery
Across all severities, prolonged or excessive bleeding following trauma, dental extraction, or surgery — disproportionate to the inciting event — is a presentation that should prompt hemophilia testing even in a patient with no prior bleeding history, particularly in mild disease.[1]
Risk Factors
- Male sex with a maternal family history of hemophilia or unexplained bleeding in maternal male relatives (a maternal uncle, grandfather, or male cousin) — the classic X-linked recessive inheritance pattern, though its absence does not exclude the diagnosis.[1]
- Being born to a known or obligate carrier mother — obligate carriers include any biological daughter of a man with hemophilia, and any biological mother of 2 or more sons with hemophilia, or of one son with hemophilia and at least one other affected or carrier relative.[1]
- A de novo F8 or F9 variant with no prior family history — genuinely common, accounting for roughly 30% of all cases and more than half of newly diagnosed severe cases, so a negative family history should never be used to argue against the diagnosis.[1]
- Being a carrier (see Special Populations) — carriers exhibit a wide range of factor levels due to lyonization (variable, essentially random inactivation of one X chromosome in each cell), and some carriers have factor levels low enough to produce a mild-to-moderate hemophilia bleeding phenotype themselves.[1][2]
Risk factors specifically for inhibitor development
A separate risk-factor set predicts which patients on factor replacement therapy are more likely to develop a neutralizing factor inhibitor (see Assessment & Diagnosis and Choose Initial Treatment for the full inhibitor framework) — this is a distinct, treatment-related risk profile, not a risk for hemophilia itself:
- Hemophilia severity — inhibitors are substantially more common in severe hemophilia A than in moderate or mild disease, and more common in hemophilia A than hemophilia B overall.[1]
- Genotype — certain F8/F9 variant types (e.g., null mutations producing no endogenous protein at all) carry materially higher inhibitor risk than missense variants, which typically allow some residual protein expression.[1]
- Family history of an inhibitor in an affected relative.[1]
- Race/ethnicity and immune-regulatory gene variants — reported associations exist, though the mechanisms are incompletely understood.[1]
- Intensity of early factor exposure — intensive treatment (e.g., for surgery or a major bleed) during the first exposures to clotting factor concentrate is associated with higher inhibitor risk than steady, lower-intensity exposure.[1]
Red Flags & Refer
Any of the following changes the plan from routine outpatient or home-treatment management to an emergency.
- Suspected intracranial hemorrhage (head trauma, however minor, with headache, vomiting, altered consciousness, seizure, or any focal neurologic sign; or truly spontaneous severe headache) in a patient with hemophilia is a true emergency. Factor replacement (or, in a patient with an inhibitor, a bypassing agent) must be given immediately, empirically, before imaging confirmation — do not wait for a CT scan to treat. This is one of the few situations in medicine where treatment precedes, rather than follows, diagnostic imaging.[1]
- Bleeding into any other critical anatomic space — neck/throat (airway compromise risk), retroperitoneal, or a large-volume gastrointestinal bleed — needs the same immediate, empiric factor/bypassing-agent replacement and emergency evaluation.[1]
- Signs of an acute hemarthrosis — new joint pain, warmth, swelling, reduced range of motion, or the prodromal "aura" some patients describe before objective swelling appears — needs prompt factor replacement, ideally within 1-2 hours of symptom onset, to genuinely minimize joint damage; a wait-and-see approach is a recognized, avoidable driver of long-term arthropathy (see Complications, below, and Common Errors to Avoid).[1]
- Breakthrough bleeding despite adequate, adherent prophylaxis — this is not simply "bad luck" and should raise concern for inhibitor development; test for an inhibitor rather than simply increasing the factor dose (see Assessment & Diagnosis and Treatment Failure & Next Step).[1]
- Suspected compartment syndrome or nerve compression from a deep muscle bleed (iliopsoas, calf, or forearm) — needs urgent factor replacement and close monitoring, with surgical consultation if compartment pressure is a genuine concern.[1]
- Any major trauma, or planned surgery/invasive procedure, in a patient with hemophilia who does not yet have a documented current treatment plan — refer for hemophilia treatment centre input well in advance rather than on the day of the procedure.[1]
- A new allergic reaction or anaphylaxis to factor IX replacement in hemophilia B — screen urgently for a factor IX inhibitor with concurrent nephrotic syndrome, a recognized and dangerous association specific to hemophilia B inhibitors (see Assessment & Diagnosis).[1]
Complications
Hemophilic arthropathy is the most important long-term complication of hemophilia and the direct consequence of recurrent, inadequately treated hemarthrosis: repeated joint bleeding drives chronic synovitis, cartilage damage, and ultimately joint destruction, producing chronic pain and disability. It is substantially preventable with effective prophylaxis and prompt bleed treatment, which is precisely why prophylactic factor replacement, rather than only treating bleeds as they occur, is now the standard of care for severe hemophilia (see Choose Initial Treatment).[1] Factor inhibitor development is the most serious treatment-related complication — inhibitors are associated with a meaningfully higher disease burden, including more musculoskeletal complications, more pain, greater treatment cost, and (in hemophilia A specifically) reported mortality roughly 5-fold higher among mild-to-moderate patients who develop an inhibitor compared with those who do not.[1] In hemophilia B specifically, an inhibitor carries the added risk of anaphylaxis to factor IX replacement, occurring in roughly half of hemophilia B patients who develop an inhibitor and more often with null F9 mutations, sometimes accompanied by nephrotic syndrome.[1]
Assessment & Diagnosis
Initial diagnosis
A definitive diagnosis is based on a factor VIII or factor IX activity assay demonstrating a specific deficiency, alongside a bleeding history and a family history of abnormal or unexplained bleeding in maternal male relatives.[1] The factor assay result also directly establishes the severity classification (see Clinical Snapshot), which in turn drives the treatment-intensity decision. Genetic testing to identify the specific causative F8 or F9 variant is increasingly used to confirm the diagnosis, inform prognosis (certain variant types carry higher inhibitor risk — see Risk Factors), and enable carrier testing and prenatal diagnosis in the wider family.[1]
Newborn testing
Cord blood should be collected from male newborns of known or potential carriers to assess clotting factor levels for early diagnosis. FVIII levels at birth are within, or mildly above, the normal adult range in an unaffected infant, so most hemophilia A can be diagnosed at birth — the exception is mild hemophilia A, where a result at the low end of the normal range should be repeated around 6 months of age. FIX levels, in contrast, are physiologically lower than normal adult levels at birth in every newborn (more so if preterm), so severe and moderate hemophilia B can usually still be diagnosed in the neonatal period, but a possible mild case needs repeat testing at 3-6 months of age.[1]
Inhibitor testing
An "inhibitor" in hemophilia is an IgG alloantibody against infused factor VIII or IX that neutralizes its hemostatic function. Inhibitors are detected and quantified with the Nijmegen-modified Bethesda assay. A positive result is defined as a titer greater than 0.6 Bethesda units (BU) for a factor VIII inhibitor, or 0.3 BU or greater for a factor IX inhibitor; a low-responding inhibitor is under 5.0 BU and a high-responding inhibitor is 5.0 BU or greater — a distinction that materially changes treatment choice (see Choose Initial Treatment).[1]
When to test for an inhibitor
Routine screening at least every 6-12 months after starting clotting factor concentrate replacement, then annually thereafter — this is when inhibitor risk is highest, particularly within the first 20 exposure days.[1]
After intensive factor exposure — clotting factor concentrate given for more than 5 consecutive days — test within 4 weeks of the last infusion.[1]
Before major surgery, and for a suboptimal post-operative response to factor replacement.[1]
For recurrent bleeding, target-joint bleeding, or any failure to respond to adequate factor replacement therapy in a previously responsive patient — this should be the default explanation to rule out before assuming a dosing problem.[1]
For lower-than-expected factor recovery or a shortened half-life after dosing (a suspected inhibitor should be confirmed by documenting poor recovery and/or a shortened half-life — under 6 hours for standard half-life FVIII, under 9 hours for standard half-life FIX — alongside repeat Bethesda testing).[1]
For a new allergic reaction or anaphylaxis to factor IX therapy in hemophilia B — screen specifically for an inhibitor with concurrent nephrotic syndrome.[1]
Inhibitory antibodies develop with a cumulative incidence of approximately 30% among previously untreated patients with severe hemophilia A (79% of these occur within the first 20 exposure days), versus only 5-10% in mild-to-moderate hemophilia A, and up to about 5% in hemophilia B overall — a materially lower rate, reflecting real biological differences between the 2 conditions that also change inhibitor management (see Choose Initial Treatment).[1]
Treatment Targets
- Prevent bleeding before it occurs wherever feasible (prophylaxis), rather than only treating bleeds after the fact — the single biggest shift in modern hemophilia care.[1]
- Treat any bleeding episode promptly — ideally within 1-2 hours of symptom onset for a joint bleed — to genuinely limit the amount of joint and tissue damage.[1]
- Prevent long-term joint damage (hemophilic arthropathy) by minimizing both the frequency and severity of hemarthrosis over a patient's lifetime, not just managing each bleed in isolation.[1]
- Maintain a factor trough level appropriate to the patient's severity, regimen, and lifestyle — historically a trough of 1% was considered sufficient; current practice increasingly targets higher troughs (greater than 3-5%, or more) where achievable, since more time spent below 1% correlates directly with more breakthrough bleeding.[1]
- Enable normal physical activity, participation, and quality of life — not just biochemical bleed prevention as an end in itself.[1]
- Detect factor inhibitors early through scheduled screening, since early detection materially changes the treatment plan and outcome (see Assessment & Diagnosis).[1]
- Individualize the specific regimen (product, dose, and interval) to the patient's own pharmacokinetics, bleeding phenotype, activities, and preferences, rather than applying one fixed protocol to everyone.[1]
Choose Initial Treatment
1st line for severe hemophilia A or B regular, scheduled factor replacement (prophylaxis), rather than treating bleeds only as they occur. Prophylaxis aims to convert a severe bleeding phenotype (baseline factor level under 1%) into one resembling moderate or mild hemophilia by keeping factor levels elevated essentially continuously, and current Canadian and international consensus favours starting it as early as feasible: age at prophylaxis initiation is a strong predictor of long-term joint outcomes, and early initiation also reduces the risk of intracranial hemorrhage, which is highest in very young children.[1] On-demand (episodic) treatment — factor given only when a bleed actually occurs — remains reasonable for milder disease with a low spontaneous-bleeding phenotype, and is sometimes used for moderate hemophilia depending on the individual's bleeding pattern.[1]
Primary prophylaxis starts before any documented joint disease and before a second clinically evident joint bleed (generally before 3 years of age); secondary prophylaxis starts after 2 or more joint bleeds but before joint disease is established; tertiary prophylaxis starts after joint disease is already documented, typically in adulthood.[1] The historical trough target of 1 IU/dL (1%) is now understood to be insufficient to fully prevent bleeding in many patients — most clinicians now aim for higher troughs (greater than 3-5%, or more) where the product, dosing interval, and patient's own pharmacokinetics allow, personalized to activity level and lifestyle rather than applied as one fixed number.[1]
Weight-based dosing follows a predictable recovery formula: in the absence of an inhibitor, each 1 IU/kg of SHL FVIII concentrate raises the plasma FVIII level by approximately 2 IU/dL (2%), and each 1 IU/kg of SHL FIX concentrate raises the plasma FIX level by approximately 1 IU/dL (1%) — FIX's larger volume of distribution is why its per-kilogram recovery is roughly half that of FVIII.[1] SHL FVIII has a half-life of approximately 12 hours in adults (shorter in young children, lengthening with age); SHL FIX has a longer half-life of approximately 18-24 hours. Because of these short half-lives, conventional SHL prophylaxis typically requires 3-4 infusions per week for FVIII and 2-3 per week for FIX.[1]
EHL products allow either fewer infusions for a similar trough, a higher trough with a similar infusion frequency, or some combination of both. The benefit is asymmetric between the 2 factors: EHL FVIII products show only a modest 1.4- to 1.6-fold half-life extension over SHL FVIII, while EHL FIX products show a substantially larger 3- to 5-fold extension, and some permit dosing as infrequently as every 7-14 days while still maintaining FIX troughs of 10-20% or higher.[1] EHL products generally have similar per-kilogram recovery to their SHL counterparts, so the dose used for a given trough target is broadly comparable — the benefit of EHL products is in the dosing interval, not a fundamentally different dose.[1]
Approved for hemophilia A, with or without inhibitors emicizumab is a bispecific, humanized monoclonal antibody that bridges activated factor IX and factor X, mimicking the cofactor function normally provided by activated factor VIII — a completely different mechanism from factor replacement, which is why it is classed as "non-factor" therapy.[3][1] It is given by subcutaneous injection: a loading dose of 3 mg/kg once weekly for the first 4 weeks, followed by a maintenance dose of 1.5 mg/kg once weekly, or 3 mg/kg every 2 weeks, or 6 mg/kg every 4 weeks, selected based on patient/caregiver preference for dosing frequency.[3] Its elimination half-life is approximately 4 weeks, which is why once-monthly maintenance dosing is feasible and why its effect on coagulation assays can persist for up to 6 months after the last dose.[3] Its far less frequent, subcutaneous dosing is a genuinely significant advance over the intravenous infusions factor replacement requires, and it is making it feasible to start prophylaxis in newborns and very young children with severe hemophilia A without needing a central venous access device.[1] Emicizumab is not intended to treat acute bleeding — breakthrough bleeds on emicizumab are treated with factor VIII replacement (or a bypassing agent, in a patient with an inhibitor) at a dose sufficient to achieve hemostasis, exactly as they would be without emicizumab on board.[1]
Caution: thrombotic microangiopathy and thromboembolism cases of thrombotic microangiopathy and thromboembolism have occurred in patients on emicizumab prophylaxis who received activated prothrombin complex concentrate (aPCC) at an average cumulative dose greater than 100 U/kg over 24 hours or more.[3] Discontinue aPCC at least 24 hours before starting emicizumab, and avoid aPCC during emicizumab treatment unless no other option is available; if aPCC genuinely must be used for a breakthrough bleed, cap the total aPCC dose at 100 U/kg or less within the first 24 hours, give any initial dose up to 50 U/kg under medical supervision, and weigh the risk of thrombotic microangiopathy/thromboembolism against the risk of the bleed itself before exceeding that cap. Discontinue aPCC immediately and interrupt emicizumab if symptoms of either complication occur.[3] Recombinant activated factor VII (eptacog alfa) has not shown this specific interaction in clinical trials, though a potential thromboembolism risk cannot be entirely excluded, and it is generally the preferred bypassing agent for a patient on emicizumab who needs one.[3]
For a patient with a factor inhibitor and an acute bleed, treatment depends on whether the inhibitor is low- or high-responding.[1] Low-responding inhibitor: factor concentrate replacement at a higher dose is often still effective, since measurable factor levels can still be achieved despite the inhibitor; careful monitoring for clinical efficacy is needed.[1] High-responding inhibitor (5.0 BU or greater): factor replacement is generally ineffective, and a bypassing agent — recombinant activated factor VII (eptacog alfa) or activated prothrombin complex concentrate (aPCC) — is required instead, working by generating thrombin through a pathway that bypasses the missing factor and its inhibitor entirely.[1] Choice between the 2 bypassing agents is individualized (prior response, bleed site/severity, and, in hemophilia B with an inhibitor and any history of an allergic reaction to factor IX, avoiding aPCC specifically because it contains factor IX and can trigger or worsen anaphylaxis — use recombinant activated factor VII instead in that situation).[1] Management of bleeding in a patient with an inhibitor should be carried out in consultation with a hemophilia treatment centre.[1]
1st line consideration for a documented responder with mild-to-moderate hemophilia A desmopressin is a synthetic vasopressin analogue that releases stored endogenous factor VIII, temporarily boosting the FVIII level roughly 3- to 6-fold.[1] It is genuinely useful when it works because it avoids the cost and the theoretical inhibitor-development risk of clotting factor concentrate — but it has real, important scope limits.[1] Does not work in hemophilia B — desmopressin has no effect on FIX levels and is of no value whatsoever in hemophilia B; do not use it for this indication.[1] Not appropriate for severe hemophilia A — with severe disease there is little to no endogenous FVIII left to release, so it will not produce a clinically useful response. The WFH specifically recommends testing an individual patient's DDAVP response before relying on it clinically, given real inter-patient variability, particularly with the intranasal route.[1] See Drug Tables for dosing, the 3-consecutive-day maximum, and fluid-restriction requirements.
Valuable as monotherapy or adjunct for mucocutaneous bleeding — epistaxis, oral bleeding, gastrointestinal bleeding, menorrhagia — and for dental surgery or bleeding from tooth eruption/shedding.[1] Tranexamic acid alone is of no value in preventing hemarthrosis — it is an adjunct for mucosal/soft-tissue bleeding, not a substitute for factor replacement in joint or muscle bleeding.[1] Do not combine with prothrombin complex concentrates (including aPCC) — the combination carries an increased thromboembolism risk; it can be combined safely with standard clotting factor concentrates and with recombinant activated factor VII.[1] Contraindicated in hematuria — obstructive uropathy risk from clot formation in the urinary tract.[1]
Non-Pharmacologic Treatment
First aid for an acute joint or muscle bleed
Follow the PRICE principles — Protection, Rest, Ice, Compression, and Elevation — as adjunctive first aid alongside prompt factor replacement (or desmopressin, where appropriate); first aid reduces the amount of treatment product needed but does not replace factor/bypassing-agent treatment for a genuine bleed.[1]
- Physical therapy and structured rehabilitation after a joint bleed, to preserve range of motion and long-term joint function — an integral part of bleed management, not an optional add-on.[1]
- Comprehensive, multidisciplinary care through a hemophilia treatment centre — the model of care associated with the best outcomes, including coordinated physiotherapy, dental care, genetic counselling, and psychosocial support.[1]
- Avoid intramuscular injections where an alternative route is feasible; when one genuinely cannot be avoided (e.g., a required vaccine), apply firm, extended direct pressure afterward.
- Avoid regular NSAID use and be cautious with antiplatelet agents or anticoagulants started for an unrelated indication — involve the hemophilia treatment centre before starting one.
- Individualized activity counselling: encourage normal activity and physical fitness (which itself supports joint health), while avoiding high collision-risk contact sports, particularly in severe, poorly-controlled disease.
- Hepatitis A and B vaccination before significant exposure to any plasma-derived blood product.[1]
- Genetic counselling and cascade carrier testing of at-risk female relatives, given the X-linked inheritance pattern (see Special Populations).[1]
- Every patient should carry medical alert identification stating their hemophilia type, severity, and current treatment plan (including inhibitor status if applicable).
- Arrange the treatment plan for any planned surgery, dental extraction, or invasive procedure well in advance through the hemophilia treatment centre, not on the day of the procedure.[1]
Patient education
Teach every patient and family caregiver to recognize bleeding early, including the subtle, non-verbal signs in infants and young children (reluctance to use a limb, unexplained fussiness with movement) — a "wait-and-see" approach to a possible bleed is a recognized, avoidable driver of progressive joint damage, not a cautious default.[1] Train patients and caregivers on self-management skills: bleed recognition, self-infusion technique and aseptic handling where home therapy is used, symptom/treatment record-keeping, and when to escalate to the hemophilia treatment centre or emergency department.[1] For anyone using desmopressin, teach the mandatory fluid-restriction rule for 24 hours after dosing and the specific hyponatremia warning signs (headache, nausea, confusion) that should prompt medical attention rather than repeat dosing.[1] Reinforce that emicizumab and prophylactic factor replacement are working even when the patient feels well, and that missing scheduled doses genuinely raises breakthrough-bleeding and long-term joint-damage risk. Teach every patient with hemophilia and every carrier the specific emergency-level red flags in this chapter — especially that any head trauma or unexplained severe headache needs immediate treatment and assessment, not a wait-and-see approach.[1]
Special Populations
Women who are carriers
Carriers are not reliably asymptomatic. Because of lyonization — the essentially random inactivation of one X chromosome in each cell — carrier factor levels vary widely, and many carriers have levels in a range typically described as roughly 30-70% of normal, though some fall low enough to produce a genuine mild or even moderate hemophilia bleeding phenotype.[2][1] A carrier with a low factor level should be treated and managed the same as a male with hemophilia of equivalent severity, not assumed to be protected by carrier status alone.[1] The most common bleeding manifestations reported among symptomatic carriers include heavy menstrual bleeding (menorrhagia), painful menstruation (dysmenorrhea), postpartum hemorrhage, perimenopausal abnormal bleeding, excessive bleeding after surgery or dental extraction, easy bruising, epistaxis, and oral cavity or musculoskeletal bleeding — joint bleeds in carriers are frequently unrecognized and underdiagnosed, which itself leads to worse joint outcomes than in males, where the bleeding is expected and looked for.[2][1] All immediate female relatives (mother, sister, daughter) of a person with hemophilia should have factor levels measured, especially before any invasive procedure, childbirth, or as soon as any abnormal bleeding occurs; in a potential carrier, genetic testing should confirm the diagnosis where available, since factor levels alone can occasionally be misleadingly normal.[1] Desmopressin is particularly useful for carriers of hemophilia A with a documented response, and hormonal therapy (combined hormonal contraception, or the levonorgestrel intrauterine device) plus oral tranexamic acid (15-25 mg/kg every 6-8 hours) are useful for managing heavy menstrual bleeding.[1]
Pregnancy in carriers
FVIII levels rise substantially through pregnancy and may normalize by the third trimester in a hemophilia A carrier; FIX levels, by contrast, do not usually change significantly, so a hemophilia B carrier does not get the same physiologic protection.[1] Even with a third-trimester FVIII/FIX level above 50 IU/dL, a carrier may still bleed abnormally during childbirth, so a bleeding history and score should be obtained before delivery regardless of the third-trimester level.[1] Assay FVIII/FIX levels in the third trimester to plan delivery. Regional (epidural) anesthesia is not contraindicated if the coagulation screen is normal and the relevant factor level is at least 50 IU/dL, whether physiologically or by prophylactic treatment. Where replacement is needed, maintain factor levels above 50 IU/dL for labour and delivery and for at least 3 days after vaginal delivery or 5 days after cesarean delivery.[1] Instrumental delivery (forceps, vacuum), fetal scalp blood sampling, and internal fetal scalp electrodes should be avoided when the fetus is known or suspected to have hemophilia, given intracranial hemorrhage risk; delivery should be atraumatic regardless of route.[1] Carriers should be monitored for both primary and secondary postpartum hemorrhage.[1] Desmopressin is not licensed in pregnancy but has been used with caution in carriers during labour and delivery; it should be avoided in pre-eclampsia/eclampsia given already-elevated VWF levels in that setting.[1]
Neonates and pediatrics
Cord blood testing and atraumatic delivery practices apply as above. Early recognition of joint bleeding is a key diagnostic clue for severe disease in a young child (see Recognize the Condition). Early initiation of prophylaxis is associated with the best long-term joint outcomes and reduces intracranial hemorrhage risk, which is highest in very young children; emicizumab's subcutaneous route is making earlier prophylaxis initiation more feasible without needing central venous access.[1] Desmopressin should be used with particular caution under 2 years of age given a materially higher hyponatremic-seizure risk from free-water retention, and total fluid intake should be reduced to about 75% of maintenance for 24 hours after any dose in this age group.[1]
Older adults
People with hemophilia are equally or more prone to obesity, hypertension, diabetes, and cardiovascular disease than the general population, and a bleeding disorder does not eliminate cardiovascular risk despite intuitively seeming protective — preventive cardiovascular risk-factor management is still needed.[1] Balancing an indicated antiplatelet agent or anticoagulant against bleeding risk in a patient with hemophilia needs hemophilia treatment centre involvement, not a decision made in isolation.
Genetic counselling and family planning
Genetic counselling should be offered to obligate and potential carriers, covering inheritance, testing options, and reproductive choices; prenatal diagnosis (determining whether a male fetus is affected) helps inform delivery planning, including consideration of cesarean delivery to reduce intracranial hemorrhage risk in an infant expected to have severe hemophilia.[1]
Monitoring & Follow-Up
Screen for a factor inhibitor at least every 6-12 months after starting clotting factor concentrate replacement, then annually thereafter, and at each of the specific trigger points in Assessment & Diagnosis (intensive exposure, before major surgery, recurrent/target-joint bleeding, or any unexpected loss of clinical response).[1] For a patient on prophylaxis with breakthrough bleeding despite documented adherence, escalate by reassessing trough levels and pharmacokinetics before simply increasing the dose, and specifically test for an inhibitor first if the patient has previously responded normally and now does not.[1] Track joint health longitudinally — physical examination and, where indicated, imaging — to catch early arthropathy before it becomes clinically obvious, since recurrent subclinical bleeding can progress joint damage even between recognized clinical bleeds.[1] Confirm a peak factor level 15-30 minutes after an infusion when verifying an unexpected dosing response, and use a measured trough level to guide subsequent dose adjustments, particularly around surgery or a major bleed requiring sustained coverage.[1] Review self-infusion technique, adherence, and the patient's bleed/treatment diary at routine hemophilia treatment centre visits — at least annually for comprehensive multidisciplinary review, more often for young children, a new diagnosis, inhibitor patients, or anyone recently changed to a new product or regimen.[1] For anyone on desmopressin, check plasma sodium and osmolality before and after dosing in young children or with repeated same-day dosing, given hyponatremia risk.[1] For emicizumab, remember its long half-life means its effect on standard coagulation assays (including a one-stage FVIII assay) persists for up to 6 months after the last dose — do not misinterpret a persistently "elevated" FVIII activity result as a treatment or diagnostic problem without accounting for this.[3]
Common Errors to Avoid
- Waiting for imaging confirmation before treating suspected intracranial hemorrhage or another critical-space bleed — treat empirically and immediately instead.[1]
- Using a "wait-and-see" approach to a possible joint or muscle bleed rather than treating promptly — this is a recognized, avoidable driver of progressive joint damage.[1]
- Giving desmopressin in hemophilia B, where it has no effect on FIX levels, or in severe hemophilia A, where there is little endogenous FVIII left to release.[1]
- Relying on desmopressin clinically without ever having documented an actual trial-of-response for that specific patient.[1]
- Assuming breakthrough bleeding on prophylaxis is simply bad luck rather than testing for an inhibitor first.[1]
- Combining tranexamic acid with a prothrombin complex concentrate (including aPCC) — increased thromboembolism risk.[1]
- Exceeding the 100 U/kg/24h aPCC dosing cap in a patient also on emicizumab, or not discontinuing aPCC at least 24 hours before starting emicizumab.[3]
- Treating an acute breakthrough bleed with emicizumab alone — it is not intended to treat active bleeding and does not substitute for factor replacement or a bypassing agent during a bleed.[1]
- Assuming a carrier is asymptomatic by definition and skipping factor-level testing or bleeding-history assessment before a procedure, childbirth, or when abnormal bleeding occurs.[2][1]
- Missing subtle, non-verbal signs of a joint or muscle bleed in an infant or young child (reluctance to use a limb) because overt swelling has not yet developed.[1]
- Giving an intramuscular injection without considering an alternative route or applying extended direct pressure afterward.
- Not restricting fluids or monitoring sodium after desmopressin, especially in a young child.[1]
- Using aPCC in a hemophilia B patient with a prior allergic reaction to factor IX — it contains factor IX and can trigger or worsen anaphylaxis; use recombinant activated factor VII instead.[1]
Clinical Decision Algorithm
Drug Tables
How to use this table: doses are adult doses and require patient-specific confirmation, including individual pharmacokinetics, weight, current inhibitor status, and the specific bleeding situation being treated. Select any linked drug name to open its complete Pharmasist Drug Database page.
Clotting Factor Concentrate Replacement
The main treatment for severe hemophilia. In the absence of an inhibitor, each 1 IU/kg of standard half-life FVIII raises plasma FVIII by approximately 2 IU/dL; each 1 IU/kg of standard half-life FIX raises plasma FIX by approximately 1 IU/dL. Dose and interval are individualized to the trough target, product half-life, and the patient's own pharmacokinetics.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Antihemophilic Factor VIII (Recombinant) -- standard half-life | Prophylaxis: Dose and interval individualized to trough target (conventionally at least 1%, current practice favours greater than 3-5% where achievable) On-demand/bleed treatment: Dose to the factor level required for the specific bleed site and severity | Infusion reactions; theoretical inhibitor development, particularly within the first 20 exposure days | None significant | Half-life approximately 12 hours in adults (shorter in young children). Conventional prophylaxis typically needs 3-4 infusions per week. |
| Antihemophilic Factor VIII (Recombinant, B-Domain Truncated), PEGylated -- extended half-life | Prophylaxis: Reduced infusion frequency or a higher trough at similar frequency, individualized to the patient | Infusion reactions; theoretical inhibitor development | None significant | Half-life approximately 1.4- to 1.6-fold longer than standard half-life FVIII. Per-kilogram recovery is broadly similar to standard half-life FVIII -- the benefit is a longer interval, not a different dose. |
| Coagulation Factor IX (Recombinant) -- standard half-life | Prophylaxis: Dose and interval individualized to trough target On-demand/bleed treatment: Dose to the factor level required for the specific bleed site and severity | Infusion reactions; theoretical inhibitor development; rare anaphylaxis (screen for a FIX inhibitor and nephrotic syndrome if it occurs) | None significant | Half-life approximately 18-24 hours. Conventional prophylaxis typically needs 2-3 infusions per week. |
| Coagulation Factor IX (Recombinant), Fc Fusion Protein -- extended half-life | Prophylaxis: Reduced infusion frequency, individualized to the patient's factor recovery and trough target | Infusion reactions; theoretical inhibitor development | None significant | Half-life approximately 3- to 5-fold longer than standard half-life FIX -- the largest infusion-frequency benefit of any product in this table; some patients can dose as infrequently as every 7-14 days. |
Non-Factor Prophylaxis
Emicizumab is a bispecific antibody mimicking the cofactor function of activated FVIII -- it is approved for hemophilia A only, with or without inhibitors, and does not treat acute bleeding.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Emicizumab | Loading dose: 3 mg/kg SC once weekly for the first 4 weeks Maintenance -- once weekly: 1.5 mg/kg SC once weekly Maintenance -- every 2 weeks: 3 mg/kg SC every 2 weeks Maintenance -- every 4 weeks: 6 mg/kg SC every 4 weeks | Injection-site reactions, headache; thrombotic microangiopathy and thromboembolism specifically with concurrent high-dose aPCC (see Interactions) | Avoid aPCC during treatment where possible; if unavoidable, cap total aPCC dose at 100 U/kg or less within the first 24 hours and discontinue aPCC at least 24 hours before starting emicizumab | Elimination half-life approximately 4 weeks -- effect on coagulation assays (including one-stage FVIII assays) can persist up to 6 months after the last dose. Not intended to treat acute bleeding; breakthrough bleeds are treated with FVIII replacement or a bypassing agent. |
Emicizumab dosing and the aPCC thrombotic-microangiopathy/thromboembolism interaction warning above are cross-checked against the current Health Canada product monograph.[3]
Bypassing Agents -- For Acute Bleeds With a High-Responding Factor Inhibitor
Generate thrombin through a pathway that bypasses the missing factor and its inhibitor. Choice is individualized to prior response, bleed site/severity, and (in hemophilia B) any history of an allergic reaction to factor IX.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Eptacog alfa (recombinant activated factor VII) | Acute bleed dosing: Individualized to bleed severity and site, per current hemophilia treatment centre protocol | Rare thromboembolism; infusion reactions | Generally the preferred bypassing agent for a patient also on emicizumab -- has not shown the specific thrombotic-microangiopathy interaction seen with aPCC, though a residual thromboembolism risk cannot be entirely excluded | Preferred bypassing agent in hemophilia B with a prior allergic reaction/anaphylaxis to factor IX therapy, since it does not itself contain factor IX. |
| Activated prothrombin complex concentrate (aPCC, e.g., FEIBA) | Acute bleed dosing: Individualized to bleed severity and site, per current hemophilia treatment centre protocol | Thrombotic microangiopathy and thromboembolism, specifically with concurrent emicizumab above the 100 U/kg/24h dosing cap | Do not combine with tranexamic acid (increased thromboembolism risk). Avoid in hemophilia B with a prior allergic reaction to factor IX -- aPCC contains factor IX and can trigger or worsen anaphylaxis; use eptacog alfa instead. | No current Pharmasist Drug Database page -- named here for awareness only, not as a platform-verified dosing reference. If used in a patient also on emicizumab, cap the total dose at 100 U/kg or less within the first 24 hours. |
Desmopressin (DDAVP) -- Mild-to-Moderate Hemophilia A Only, Documented Responder
Releases stored endogenous FVIII -- has no effect on FIX and is of no value in hemophilia B; not appropriate for severe hemophilia A given minimal endogenous FVIII to release. Test individual response before relying on it clinically. Named as text only in this chapter: the Drug Database's only "desmopressin" page is the low-dose oral melt tablet dosed for diabetes insipidus/nocturnal enuresis, a different formulation, concentration, and dose entirely from the concentrated hemostatic products below.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Desmopressin acetate, concentrated IV/SC injection | Standard dose: 0.3 mcg/kg IV (diluted in at least 50-100 mL normal saline, infused over 20-30 minutes) or the same dose SC Fluid management: Restrict fluids for 24 hours after dosing; in children under 2 years, total fluid intake should be reduced to about 75% of maintenance | Flushing, headache, transient tachycardia/hypotension; water retention and hyponatremia, especially with repeated same-day dosing or excess fluid intake | Additive hyponatremia risk with other antidiuretic drugs or excess hypotonic IV fluids | A single dose can be expected to boost FVIII roughly 3- to 6-fold. Infuse IV doses slowly over 20-30 minutes; peak response is seen at approximately 60 minutes. Do not use for more than 3 consecutive days -- tachyphylaxis develops with repeated dosing. |
| Desmopressin acetate, concentrated intranasal spray (1.5 mg/mL) | Adult dose: 1 spray (150 mcg) in each nostril; a single spray in 1 nostril if body weight is under 40 kg | Nasal irritation, headache, facial flushing; hyponatremia with repeated dosing | Additive hyponatremia risk with other antidiuretic drugs or excess hypotonic IV fluids | Response to the intranasal route is more variable and less predictable than IV/SC dosing. Contraindicated under 2 years of age; use with particular caution in young children given a materially higher hyponatremic-seizure risk. |
Concentrated hemostatic desmopressin dosing above is cross-checked against the current Health Canada product monograph.[4]
Antifibrinolytic Adjunct
Effective as monotherapy for minor mucocutaneous bleeding, and as an adjunct to factor replacement or a bypassing agent around a larger bleed or procedure. Not effective alone for preventing or treating hemarthrosis.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Tranexamic acid | Oral: 25 mg/kg per dose, 3-4 times daily, usually for about 7 days IV: 10 mg/kg per dose, 2-3 times daily, infused slowly | Nausea, GI upset; dizziness/hypotension with rapid IV injection | Never combine with a prothrombin complex concentrate, including aPCC (increased thromboembolism risk). Contraindicated in hematuria (obstructive uropathy risk). May be combined with standard factor concentrates or with recombinant activated factor VII. | Also available as an oral rinse, useful for dental procedures and bleeding from tooth eruption/shedding. |
Tranexamic acid dosing above is cross-checked against the current Health Canada product monograph.[5]
Evidence note: factor replacement dosing principles, inhibitor definitions, and desmopressin/tranexamic acid indications above reflect the current WFH Guidelines for the Management of Hemophilia, 3rd edition.[1]
References
- WFH Guidelines for the Management of Hemophilia, 3rd edition — World Federation of Hemophilia (Srivastava A, Santagostino E, Dougall A, Kitchen S, Sutherland M, Pipe SW, et al.); headquartered in Montreal, Quebec, Canada. Haemophilia 2020;26(S6):1-158
- Carriers of Hemophilia A and B — Bleeding Disorders Canada (formerly the Canadian Hemophilia Society). Patient/family education resource
- HEMLIBRA (emicizumab injection) Product Monograph — Hoffmann-La Roche Limited, Health Canada Drug Product Database. Health Canada Product Monograph, revised March 6, 2025
- OCTOSTIM (desmopressin acetate) Injection and Nasal Spray Product Monograph — Ferring Inc., Health Canada Drug Product Database. Health Canada Product Monograph
- CYKLOKAPRON (tranexamic acid) Product Monograph — Pfizer Canada ULC, Health Canada Drug Product Database. Health Canada Product Monograph
- Canadian Bleeding Disorders Registry (CBDR) — Association of Hemophilia Clinic Directors of Canada (AHCDC). National clinical registry, Canadian hemophilia treatment centres
Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.