Hyperparathyroidism

Hyperparathyroidism is excess secretion of parathyroid hormone (PTH), the hormone that raises serum calcium by mobilizing bone, increasing renal calcium reabsorption and phosphate excretion, and boosting renal activation of vitamin D to increase gut calcium absorption. Three mechanistically distinct forms share the name but are genuinely different diseases, not points on one severity spectrum:^[1]

PHPT is most commonly diagnosed after age 50, with women outnumbering men by roughly three to fourfold.^[1] Its clinical presentation has shifted dramatically over the past several decades: in jurisdictions with routine multichannel biochemical screening (Canada and the United States among them), the overwhelming majority of cases are now identified incidentally through a routinely measured calcium — the classical florid presentation is now uncommon in North America, though it remains the dominant presentation in parts of the world without routine screening.^[1][2] A commonly cited U.S. estimate places overall PHPT prevalence at roughly 0.86% of the general population, with more recent U.S. incidence estimates of approximately 233 and 85 per 100,000 women and men respectively.^[1][2]

This chapter deliberately does not re-explain two topics the platform already covers in full elsewhere: acute severe-hypercalcemia management (including hypercalcemic crisis) is covered in the platform's Hypercalcemia chapter, and detailed CKD-mineral-bone-disease management (active vitamin D analogs, phosphate binders, dialysis-specific calcimimetic dosing) is covered in the platform's Chronic Kidney Disease chapter — both are cross-referenced from the relevant sections below rather than duplicated. This chapter is also entirely separate from hypoparathyroidism, covered in its own chapter — the two conditions have opposite pathophysiology, causes, and management and are never interchangeable.

Primary hyperparathyroidism

The dominant modern presentation is asymptomatic disease — an incidental elevated calcium (with or without symptoms the patient had not attributed to anything) found on routine bloodwork, with PTH testing then confirming the diagnosis.^[1] This is a genuine shift from the historical teaching of "stones, bones, groans, and psychiatric overtones," which still applies to more advanced or symptomatic disease and to regions without routine biochemical screening:^[1]

Parathyroid carcinoma (under 1% of PHPT) should be actively suspected — not simply ruled in after surgery — when severe hypercalcemia (albumin-corrected calcium often above roughly 3 mmol/L / 14 mg/dL) is accompanied by a markedly elevated PTH (a PTH at 3x the upper limit of normal is suspicious; 10x the upper limit of normal carries a positive predictive value of roughly 84% for carcinoma), a palpable neck mass (present in a large minority to majority of cases — an unusual finding in benign PHPT), or rapidly progressive symptoms; new hoarseness or vocal fold weakness on examination suggests recurrent laryngeal nerve involvement from local invasion. See Red Flags & Referral.^[3]

Secondary hyperparathyroidism

Presents through its underlying driver rather than through its own symptoms — a patient with CKD or vitamin D deficiency found to have an elevated PTH with a low or low-normal (not elevated) calcium on routine bloodwork. The parathyroid response itself is rarely what brings the patient to attention.

Tertiary hyperparathyroidism

Suspect this in a patient with longstanding CKD or dialysis, previously on an expected secondary-hyperparathyroidism trajectory, who develops new or worsening hypercalcemia alongside a persistently or increasingly elevated PTH despite standard CKD-mineral-bone-disease therapy — the glands have become autonomous.

Primary hyperparathyroidism

• Sporadic single parathyroid adenoma — the cause in roughly 80-85% of cases, with no identifiable predisposing lifestyle factor.^[1]
• Multi-gland hyperplasia — roughly 15% of cases; carries a higher risk of persistent or recurrent disease after surgery since any remnant left in situ is, by definition, abnormal.^[1]
• Parathyroid carcinoma — under 1% of cases; see Recognize the Condition and Red Flags & Referral for the features that should raise suspicion.^[1]
• Prior therapeutic neck irradiation.
• Lithium therapy — a genuinely pharmacist-relevant cause, shifting the calcium-sensing receptor's set point and producing a PHPT-like picture; bilateral neck exploration is generally required if surgery is pursued, since the abnormality is often multi-gland.^[1]
• Hereditary syndromes — more likely in patients under 35 years old or with a suggestive family history: multiple endocrine neoplasia (MEN) type 1, 2A, or 4; hyperparathyroidism-jaw tumor syndrome (CDC73 gene mutation, associated with malignant potential); and familial isolated hyperparathyroidism. Genetic testing is advised for unsuccessful prior parathyroid surgery, hypercalcemia onset under 25-30 years in the patient or a relative, or a family history of hypercalcemia.^[1]

Secondary hyperparathyroidism

• Chronic kidney disease — the leading driver; phosphate retention and reduced renal 1,25-dihydroxyvitamin D synthesis both lower calcium and stimulate PTH. Full CKD-mineral-bone-disease detail is covered in the platform's Chronic Kidney Disease chapter.
• Vitamin D deficiency or insufficiency — from inadequate sun exposure or intake, malabsorption syndromes, or obesity; a common and easily correctable driver.
• Malabsorption syndromes affecting calcium and vitamin D absorption.
• Medications that reduce calcium or vitamin D availability, including loop diuretics and certain anticonvulsants that accelerate vitamin D metabolism.

Tertiary hyperparathyroidism

• Prolonged, poorly-controlled secondary hyperparathyroidism — almost exclusively seen in advanced CKD or long-standing dialysis, where sustained stimulation drives glandular hyperplasia and eventual autonomy.

The core lab pattern

An elevated albumin-corrected total serum calcium (or elevated ionized calcium with a normal corrected total calcium) in the presence of an elevated or inappropriately normal PTH is the diagnostic pattern for primary hyperparathyroidism.^[1] Both second- and third-generation PTH assays provide comparable diagnostic results.^[1] By contrast, secondary hyperparathyroidism shows an elevated PTH with a low or low-normal calcium — the opposite calcium pattern, and the key feature that distinguishes it from primary disease. Tertiary hyperparathyroidism shows an elevated PTH and an elevated calcium in a patient with a longstanding secondary-hyperparathyroidism history (advanced CKD/dialysis) — distinguished from primary disease by that clinical context rather than by the biochemistry alone.

The key differential: familial hypocalciuric hypercalcemia (FHH)

FHH is a rare autosomal-dominant disorder (three genetically distinct variants — CaSR, GNA11, and AP2S1 mutations) that mimics PHPT biochemically but reflects a fundamentally different problem: a reset calcium-sensing receptor, not autonomous parathyroid tissue.^[1] Parathyroidectomy does not cure FHH and should not be performed for it, since the receptor defect persists in the kidney and any remaining parathyroid tissue.^[1] Calculate the calcium-to-creatinine clearance ratio (CaCrCR) in every newly diagnosed patient: a ratio below 0.01 makes FHH likely, a ratio above 0.02 makes it unlikely, and the 0.01-0.02 range genuinely overlaps with PHPT and needs clinical correlation (family history, age of onset, prior unsuccessful parathyroid surgery) — DNA sequencing can confirm the diagnosis when suspicion remains.^[1] A low CaCrCR can also occur in PHPT itself with renal insufficiency or severe calcium/vitamin D deficiency, and is more often low in patients of African descent — interpret it in context rather than as a standalone rule-out.^[1]

Also screen for medication-induced hypercalcemia that can mimic or unmask PHPT — thiazide diuretics and lithium both reduce urinary calcium excretion or otherwise raise serum calcium and should be specifically asked about on medication review.^[1]

Investigations once the diagnosis is confirmed

• Serum phosphate, creatinine/eGFR, and 25-hydroxyvitamin D — vitamin D deficiency is common in PHPT and is associated with more severe biochemical and skeletal disease; correcting it is safe and does not typically worsen hypercalcemia (see Non-Pharmacologic Management).^[1]
• Bone mineral density by DXA at three sites — lumbar spine, femoral neck/total hip, and the one-third distal radius — since lumbar spine BMD is often relatively preserved in PHPT and can under-represent the true cortical-bone impact; a vertebral fracture assessment or spine X-ray to detect an otherwise-silent fragility fracture.^[1]
• Renal imaging (X-ray, ultrasound, or CT) for silent nephrolithiasis or nephrocalcinosis in asymptomatic patients being assessed for surgical criteria, together with a 24-hour urine calcium.^[2]
• Genetic testing where a hereditary syndrome is suspected (age under 35, family history, syndromic features) — see Risk Factors.

Parathyroid imaging — for surgical planning, not diagnosis

Sestamibi scintigraphy (with or without SPECT/CT), ultrasound, and four-dimensional CT are used to localize an adenoma once surgery is being planned — imaging is not a diagnostic test for PHPT, and a negative or discordant scan should never override a biochemically confirmed diagnosis or preclude surgery with an experienced parathyroid surgeon.^[1] Concordant sestamibi and ultrasound findings can predict correct side-localization with a positive predictive value as high as roughly 97%.^[1]

Secondary and tertiary hyperparathyroidism

Once the primary-vs-secondary calcium/PTH pattern points toward secondary disease, direct the workup at the driver: eGFR and a full CKD assessment (see the platform's Chronic Kidney Disease chapter), 25-hydroxyvitamin D, and a malabsorption work-up where indicated by history. In a dialysis or advanced-CKD patient with new hypercalcemia superimposed on a previously appropriate secondary picture, consider tertiary hyperparathyroidism and involve nephrology.

• For primary hyperparathyroidism — definitive cure via parathyroidectomy where indicated and accepted, normalizing both calcium and PTH permanently.^[1]
• Where surgery is not pursued — normalize or meaningfully lower serum calcium, protect bone density and reduce fracture risk, and prevent progression of renal stone disease and decline in kidney function.
• For secondary hyperparathyroidism — correct the underlying driver (vitamin D repletion, or CKD-mineral-bone-disease management per the CKD chapter) rather than targeting the parathyroid glands directly; PTH and calcium normalize as the driver resolves.
• For tertiary hyperparathyroidism — control PTH and calcium in the CKD/dialysis population per the CKD chapter's protocol, escalating to parathyroidectomy if medical therapy cannot control it.
• Avoid iatrogenic hypocalcemia from medical therapy (cinacalcet) or from an inadequately anticipated hungry bone syndrome after surgery.
• Identify and remove reversible contributors on medication review — thiazide diuretics and lithium in particular — in coordination with the prescriber rather than unilaterally.

^[2] Parathyroidectomy is also a reasonable, appropriate option for a patient who prefers surgery even without meeting any criterion, provided there are no contraindications.^[1] A minimally invasive approach is standard once a single adenoma is localized preoperatively, with similar cure and complication rates to open surgery; an open, bilateral exploration is preferred when imaging fails to localize an adenoma or multi-gland disease/familial disease is suspected (e.g. MEN-1 or lithium-induced disease).^[1] Intraoperative PTH monitoring — a drop of at least 50% into the normal range within 5-15 minutes of resection — confirms adequate resection.^[1]

Not meeting criteria, declines surgery, or not a surgical candidate move to medical management — see below and Pharmacologic Treatment Options. Monitoring without surgery appears safe for up to roughly 8-10 years in appropriately selected patients, with regular biochemical and BMD surveillance (see Monitoring & Follow-Up), though a genuine minority eventually show BMD decline or biochemical progression and should be reassessed for surgery at that point.^[1]

Medical management of primary hyperparathyroidism (not undergoing surgery)

Foundation, everyone correct vitamin D deficiency/insufficiency to a target 25-hydroxyvitamin D above 50 nmol/L (ideally above 75 nmol/L / 30 ng/mL) — this lowers PTH without worsening hypercalcemia in the available trial data, and should not be withheld out of a mistaken concern that vitamin D will aggravate the hypercalcemia.^[1] Ensure adequate hydration, unrestricted (not excessive) dietary calcium intake per usual population guidelines, and review the medication list for thiazide diuretics or lithium that could be contributing (see Non-Pharmacologic Management).

Hypercalcemia is the dominant problem cinacalcet — see Pharmacologic Treatment Options and the drug table below for full dosing, titration, and monitoring detail. It is not recommended as routine first-line therapy ahead of a genuine surgical-candidacy assessment; it is a targeted option for a patient who is symptomatic or has clinically meaningful hypercalcemia and cannot or will not have surgery, or has unresectable parathyroid carcinoma.^[1]

Osteoporosis/low BMD is the dominant problem an amino-bisphosphonate (alendronate has the most PHPT-specific trial data) for skeletal protection — see the platform's Osteoporosis chapter for full dosing/administration detail, which this chapter does not duplicate. Bisphosphonates improve BMD in PHPT by a magnitude broadly similar to what is seen after successful parathyroidectomy, but they do not lower serum calcium and there is no PHPT-specific fracture-reduction data for any medical therapy.^[1]

Secondary hyperparathyroidism

Not surgery-first, and not cinacalcet-first treat the underlying driver. For vitamin D deficiency/insufficiency, correct it directly. For CKD-driven secondary hyperparathyroidism, follow the platform's Chronic Kidney Disease chapter's CKD-mineral-bone-disease pathway (phosphate control, active vitamin D analogs, and calcimimetic therapy where indicated) — that chapter already covers this ground in full and is not duplicated here.

Tertiary hyperparathyroidism

Managed initially per the same CKD-mineral-bone-disease pathway; parathyroidectomy is reserved for disease that remains refractory to optimized medical therapy in the dialysis/advanced-CKD population, coordinated with nephrology.

• Do not restrict dietary calcium in PHPT — a genuinely counterintuitive but well-supported point. Follow ordinary population guidance (roughly 800 mg/day for women under 50 and men under 70; roughly 1000 mg/day for women 50+ and men 70+) rather than either restricting or over-supplementing.^[1]
• Correct vitamin D deficiency/insufficiency to a target 25-hydroxyvitamin D above 50 nmol/L (ideally above 75 nmol/L) — trial data shows this lowers PTH by up to roughly 26% without a clinically meaningful rise in mean serum calcium, though a minority of patients can see a modest urinary calcium increase, so pair correction with routine monitoring rather than an unmonitored high-dose empiric course.^[1]
• Maintain good hydration — reduces nephrolithiasis risk and helps limit exacerbation of hypercalcemia; this is a foundation-level measure for every patient with PHPT, not only those with acute hypercalcemia (see the Hypercalcemia chapter for acute-setting hydration/fluid management).
• Encourage regular weight-bearing activity and avoid prolonged immobilization, which promotes bone resorption and can worsen hypercalcemia.
• Medication review — avoid thiazide diuretics and lithium where alternatives exist; both can worsen or unmask hypercalcemia. This is a genuinely pharmacist-relevant intervention: raise it with the prescriber rather than advising the patient to stop a psychiatrically necessary lithium regimen unilaterally.^[1]
• Regular BMD surveillance (roughly every 1-2 years) and annual biochemical monitoring (calcium, PTH, creatinine) for any patient managed without surgery — see Monitoring & Follow-Up.^[1]
• For secondary hyperparathyroidism from CKD, dietary phosphate moderation and adherence to the broader CKD-mineral-bone-disease plan — see the platform's Chronic Kidney Disease chapter for detail.
• Genetic counselling where a hereditary syndrome (MEN1, MEN2A, hyperparathyroidism-jaw tumor syndrome, familial isolated hyperparathyroidism) is identified, given the implications for family members and, for some syndromes, associated malignancy risk.

Secondary/tertiary hyperparathyroidism in CKD — active vitamin D analogs, phosphate binders, and cinacalcet/etelcalcetide in dialysis-dependent disease are managed per the platform's Chronic Kidney Disease chapter, which is not duplicated here.

Children and young adults

PHPT under age 35, and particularly in children, is disproportionately associated with hereditary syndromes (MEN1, MEN2A, hyperparathyroidism-jaw tumor syndrome, familial isolated hyperparathyroidism) — see Risk Factors for genetic-testing indications. Parathyroidectomy is generally advised regardless of the standard asymptomatic-criteria table given the age-under-50 criterion alone, with surgical success rates and BMD recovery similar to adults.^[1]

Older adults

Surgery remains appropriate in older patients who meet criteria and are medically stable, but advancing age is associated with greater perioperative morbidity and mortality — weigh the benefits of cure against individualized surgical risk rather than applying a blanket age cutoff for withholding surgery.^[1]

Renal impairment

An eGFR below 60 mL/min is itself one of the surgical criteria for asymptomatic PHPT (see Choose Initial Treatment), reflecting evidence that successful parathyroidectomy can help prevent further decline in renal function.^[1] For CKD-driven secondary or tertiary hyperparathyroidism, follow the platform's Chronic Kidney Disease chapter's CKD-mineral-bone-disease pathway rather than this chapter's primary-HPT-focused medical management — cinacalcet is not indicated for secondary hyperparathyroidism in CKD patients who are not on dialysis, a genuine and specific safety distinction from its use in primary HPT/parathyroid carcinoma.^[4]

Hepatic impairment

Cinacalcet exposure increases in moderate-to-severe hepatic impairment — monitor serum calcium, phosphate, and PTH more closely in this population rather than assuming standard titration intervals apply.^[4]

Seizure history

Hypocalcemia lowers the seizure threshold, and cinacalcet-induced hypocalcemia carries a specific seizure risk (reported in clinical trials at a higher rate than placebo) — use added caution and closer calcium monitoring in a patient with a known seizure disorder.^[4]

• Cinacalcet: check serum calcium within about 1 week of initiation or any dose adjustment during titration; once a maintenance dose is established, monitor serum calcium approximately every 2 months for parathyroid carcinoma/primary HPT.^[4] If calcium falls below roughly 2.1 mmol/L (8.4 mg/dL) but stays above roughly 1.9 mmol/L (7.5 mg/dL), or hypocalcemia symptoms occur, manage with calcium supplementation and/or vitamin D sterols; if calcium falls below roughly 1.9 mmol/L (7.5 mg/dL) or symptoms persist, withhold cinacalcet until calcium reaches at least roughly 2.0 mmol/L (8.0 mg/dL) and symptoms resolve, then restart at the next lowest dose.^[4]
• Managed without surgery (no cinacalcet): annual biochemical profile — calcium, PTH, creatinine/eGFR — and BMD every 1-2 years; the natural history literature shows BMD can remain stable for roughly 8 years before declining in a minority of patients, so ongoing surveillance genuinely matters even after an initially reassuring period.^[1]
• After parathyroidectomy: monitor closely for hungry bone syndrome in the immediate postoperative period, particularly in patients with severe preoperative bone disease or uncorrected vitamin D deficiency; confirm biochemical cure with a normalized calcium and PTH; watch for persistent disease (hypercalcemia within 6 months, up to roughly 5% of cases) or recurrent disease (new hypercalcemia years later, up to roughly 8% over 3-11 years, higher with double adenomas) and re-refer for evaluation rather than assuming a stable postoperative calcium is a permanent guarantee.^[1]
• Secondary/tertiary hyperparathyroidism in CKD: follow the monitoring protocol in the platform's Chronic Kidney Disease chapter (PTH, calcium, phosphate per the CKD-mineral-bone-disease schedule).
• Reconcile the medication list at every visit for a newly started thiazide, lithium, or other calcium-affecting drug in a patient with known PHPT.

1. Cinacalcet with inadequate calcium control despite reaching the maximum tolerated/labeled dose: reassess adherence and GI tolerability first, then reassess surgical candidacy with the surgical team rather than continuing to escalate medical therapy indefinitely.
2. Persistent hypercalcemia and low BMD together despite cinacalcet monotherapy: consider adding a bisphosphonate for the skeletal component — cinacalcet does not meaningfully change BMD or bone turnover markers on its own, so this is an addition, not a substitution.^[1]
3. Hypercalcemia recurs within 6 months of parathyroidectomy (persistent disease) or years later (recurrent disease): re-image to localize residual/recurrent abnormal tissue and refer for reoperation at an experienced center; reoperation success rates exceed roughly 90% when the abnormal tissue is localized preoperatively, though complication risk is higher than at first surgery.^[1]
4. A patient thought to have sporadic PHPT does not respond to surgery as expected, or the biochemical pattern does not fit cleanly: reconsider FHH (recheck the CaCrCR, consider DNA testing) — parathyroidectomy will not cure FHH and a missed diagnosis here explains an apparent surgical "failure."
5. Secondary hyperparathyroidism does not improve despite vitamin D correction and standard measures: refer to nephrology and escalate per the CKD-mineral-bone-disease pathway in the platform's Chronic Kidney Disease chapter rather than trialing primary-HPT-directed therapy.
6. Tertiary hyperparathyroidism remains refractory to optimized medical therapy in a dialysis patient: refer for parathyroidectomy, coordinated with nephrology.
7. Intraoperative discovery of a gland suspicious for carcinoma: en bloc resection of the parathyroid lesion with the ipsilateral thyroid lobe and any invaded structures, rather than a standard adenoma excision.^[1]

• Treating secondary hyperparathyroidism (elevated PTH with a low or low-normal calcium) as though it were primary disease — the correct response is fixing the underlying driver (vitamin D repletion, or the CKD pathway), not parathyroid-directed therapy or cinacalcet.
• Restricting dietary calcium in PHPT — this is not indicated and runs contrary to the actual evidence base; follow ordinary population intake guidance instead.^[1]
• Withholding vitamin D correction in a PHPT patient with documented deficiency out of concern it will worsen hypercalcemia — the trial data does not support that concern at standard correction doses, and untreated deficiency is itself associated with more severe disease.^[1]
• Reaching for cinacalcet as routine first-line therapy before a genuine surgical-candidacy assessment has actually been done.
• Missing FHH and pursuing parathyroidectomy that cannot succeed — always calculate the CaCrCR in a newly diagnosed patient.^[1]
• Treating parathyroid imaging (sestamibi, ultrasound, 4D-CT) as a diagnostic test — it is a preoperative localization tool only, and a negative scan does not exclude PHPT or preclude surgery.^[1]
• Attempting fine-needle aspiration of a mass suspicious for parathyroid carcinoma, given the tumor-seeding risk along the needle tract.^[3]
• Continuing a thiazide diuretic or lithium unchanged in a newly diagnosed PHPT patient without raising it with the prescriber.^[1]
• Using cinacalcet in a CKD patient who is not on dialysis — it is not indicated for that population.^[4]
• Missing hungry bone syndrome risk in the early postoperative period for a patient with severe preoperative bone disease or uncorrected vitamin D deficiency.
• Treating hyperparathyroidism and hypoparathyroidism as though they sit on one severity spectrum — they are distinct diseases with opposite biochemistry, causes, and management; see this platform's separate Hypoparathyroidism chapter.

How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, baseline calcium). Select any linked drug name to open its complete Pharmasist Drug Database page.

Calcimimetic — the central non-surgical pharmacotherapy for primary hyperparathyroidism

Increases the calcium-sensing receptor's sensitivity to extracellular calcium, directly lowering PTH secretion and, in turn, serum calcium. Normalizes calcium in roughly 70-80% of PHPT patients and this effect is maintained over years of treatment, but calcium returns to baseline if the drug is stopped; it does not improve BMD or bone turnover markers on its own.

Bone protection (when surgery is deferred or declined and significant osteoporosis is present)

Improves BMD and lowers bone turnover markers in PHPT by a magnitude broadly comparable to successful parathyroidectomy, but has no effect on serum calcium and no PHPT-specific fracture data. Full dosing, administration rules, and monitoring are covered in the platform's Osteoporosis chapter and are only summarized here.

Vitamin D repletion and calcium intake — foundation therapy

Correcting concurrent vitamin D deficiency/insufficiency lowers PTH without a clinically meaningful rise in mean serum calcium in the available trial data, and should not be withheld out of a mistaken concern that it will worsen hypercalcemia. Dietary calcium should follow ordinary population guidance — restriction is not indicated in PHPT.

Secondary and tertiary hyperparathyroidism in CKD. Active vitamin D analogs (calcitriol, alfacalcidol), phosphate binders, and calcimimetic therapy (cinacalcet in dialysis-dependent CKD, or etelcalcetide) are managed per the CKD-mineral-bone-disease pathway detailed in the platform's Chronic Kidney Disease chapter — dosing, titration, and monitoring for that population are deliberately not duplicated in this chapter.