Kidney Stones

Kidney stones (nephrolithiasis, or urolithiasis when referring generally to a stone anywhere in the urinary tract) are solid, crystalline concretions that form when urine becomes supersaturated with stone-forming salts, which precipitate and aggregate within the kidney or ureter.^[1] They are common, and incidence is rising: contemporary estimates put lifetime prevalence at up to 10-12% in men and 7-8% in women.^[2] Once a person has had one symptomatic stone, recurrence is genuinely likely — reported at 30-50% within 10 years^[3] — which is why this chapter covers not only the acute presentation but also composition-specific secondary prevention.

Stone composition

Stone type determines both the clinical picture (notably, radiolucency on plain X-ray) and the specific secondary-prevention strategy (see Pharmacologic Treatment Options), so recognizing the likely composition matters from the first assessment.

• Calcium stones are by far the most common, accounting for roughly 64-92% of stones in adults in developed countries — calcium oxalate alone (32-46%), calcium phosphate alone (3-5%), or a mixture of the two (29-40%).^[4]
• Uric acid stones account for roughly 3-16% of stones.^[4] They are notable for being radiolucent on plain X-ray — unlike calcium-containing stones, which are radio-opaque — and typically form in the setting of persistently acidic urine, often associated with gout, high-purine/high-animal-protein diets, obesity, and type 2 diabetes.^[4][3]
• Struvite (infection) stones account for roughly 2-15% of stones.^[4] They form specifically in the setting of infection with a urease-producing organism (classically Proteus), which alkalinizes the urine and drives precipitation of magnesium ammonium phosphate; struvite stones can grow rapidly and are the type capable of forming large, branching "staghorn" calculi that fill the renal collecting system.
• Cystine stones are rare, accounting for roughly 1% of stones,^[4] and result from cystinuria, an autosomal recessive genetic disorder of defective renal tubular reabsorption of dibasic amino acids that affects roughly 1 in 7000 people; cystine stone formers tend to present in childhood or the teenage years, often with recurrent stones needing repeated surgical intervention.^[3]

Renal colic

The classic presentation is renal colic: severe, sudden-onset flank pain that typically originates at the costovertebral angle and, as the stone migrates down the ureter, extends anteriorly and inferiorly toward the groin, testicle, or labia.^[1] Pain arises from ureteral muscle spasm and increased peristalsis against the obstruction, dilation of the proximal ureter and renal pelvis, and stretching of the renal capsule, which activates submucosal stretch receptors and triggers local prostaglandin release.^[1] Pain is often cramping and intermittent, or genuinely colicky, waxing and waning with ureteral peristalsis, though it can also be unrelenting.^[4]

A genuinely useful bedside distinguishing feature: patients with renal colic are classically unable to find a comfortable position and will writhe, pace, or constantly shift position trying to find relief — in sharp contrast to patients with peritoneal irritation (e.g., appendicitis, a perforated viscus), who instinctively lie still because movement worsens their pain.^[1] The relative absence of true peritoneal signs on examination further supports renal colic over an intra-abdominal surgical process.^[1]

Associated symptoms

Nausea, vomiting, and malaise commonly accompany the pain; fever and chills may also occur and should immediately raise concern for a concurrent infected, obstructed system rather than being dismissed as a nonspecific accompaniment (see Red Flags/Refer).^[4] Hematuria — gross or microscopic — is common and supports the diagnosis, though its absence does not exclude a stone.^[4] As a stone reaches the distal ureter near the bladder, patients may also develop urinary urgency, frequency, or dysuria that can mimic a urinary tract infection.

The single most important modifiable risk factor: fluid intake

Low fluid intake is genuinely the single most important, and most universally modifiable, risk factor for stone formation. Achieving a daily urine output of about 2.5 L has been shown in multiple meta-analyses to reduce the risk of stone formation by 60-80%,^[3] while poor fluid intake — particularly under 1.4 L of urine daily — increases lithogenic risk.^[3] Each additional 200 mL of daily fluid intake reduces stone risk by roughly 13%.^[3] See Non-Pharmacologic Management for practical counselling strategies.

Dietary factors

• High dietary sodium increases urinary calcium excretion and decreases urinary citrate — a natural stone-formation inhibitor — and has been associated with up to a 61% increase in stone risk in a large prospective cohort.^[3]
• High animal protein and purine intake increases urinary uric acid excretion and decreases urinary citrate and pH, predisposing to both calcium oxalate and uric acid stones.^[3]
• High dietary oxalate (e.g., spinach, nuts, chocolate, tea) contributes directly to calcium oxalate stone formation, particularly in patients with hyperoxaluria.^[3]
• Low dietary calcium — a genuinely counterintuitive but important counselling point. A persistent public misconception is that stone formers should restrict dietary calcium. In fact, multiple large prospective cohort studies show the opposite: lower dietary calcium intake is associated with a higher risk of stone formation, not a lower one.^[3] This is because calcium consumed with meals binds dietary oxalate in the gut, reducing the amount of free oxalate available for intestinal absorption and, ultimately, urinary excretion; a low-calcium diet leaves more oxalate free to be absorbed and excreted in urine, where it can combine with calcium to form stones. The actual recommendation is adequate — not restricted — dietary calcium, taken with meals (see Non-Pharmacologic Management).^[3]
• Low intake of fiber, fruits, and vegetables is associated with a modestly increased stone risk in women.^[3]
• High-dose vitamin C supplementation (over 1000 mg daily) modestly increases stone risk, since excess vitamin C is converted to oxalate.^[3]

Other risk factors

Obesity, type 2 diabetes, and metabolic syndrome are independent risk factors for stone formation — patients with metabolic syndrome have a 2.13-fold increased odds of stone disease, and risk rises with the number of metabolic syndrome features present.^[3] Family history is genuinely common among stone formers, present in 35-65% of patients with recurrent nephrolithiasis, reflecting a real heritable component (heritability of both kidney stones and urinary calcium excretion exceeds 45% in twin studies).^[3] Certain metabolic and systemic conditions increase stone risk and warrant an in-depth metabolic evaluation when present, including gout, inflammatory bowel disease (via enteric hyperoxaluria), primary hyperparathyroidism, distal renal tubular acidosis, sarcoidosis, and cystinuria (see Assessment & Diagnosis).^[3]

Left unrecognized or inadequately treated, stone disease can cause real, sometimes irreversible harm: an infected, obstructed kidney can progress rapidly to urosepsis; prolonged or repeated obstruction can cause permanent nephron loss and reduced renal function; and struvite/staghorn calculi in particular can silently damage renal parenchyma over time, since a stone that has already filled the collecting system may no longer produce classic colicky pain. Recurrent stone disease itself is also associated with an increased long-term risk of chronic kidney disease and of reduced bone mineral density.^[3]

History and examination

Characterize the pain (location, radiation, colicky versus constant), and ask specifically about fever/chills, gross hematuria, prior stone episodes, and urinary symptoms. Peritoneal signs are typically absent in uncomplicated renal colic; their presence should prompt consideration of an alternative or concurrent intra-abdominal process.^[1]

Laboratory testing

Urinalysis (looking for hematuria, and for pyuria/nitrites suggesting infection) and urine culture are appropriate for any patient presenting with suspected renal colic; basic serum studies (electrolytes, creatinine, calcium) help assess renal function and screen for an underlying metabolic driver.^[3] Hematuria supports the diagnosis but its absence does not exclude a stone.^[4]

Non-contrast coronal CT showing multiple bilateral renal calculi. Non-contrast CT remains the imaging gold standard for stone detection and characterization. (Kristie Guite, Louis Hinshaw, and Fred Lee, CC BY 3.0, Wikimedia Commons)

Imaging

Ultrasonography, ideally combined with a kidney-ureter-bladder (KUB) X-ray, is recommended as the initial imaging modality of choice for acute ureteral stones, given comparable clinical outcomes to CT with no radiation exposure; a large randomized trial found most outcomes equivalent between ultrasound and non-contrast CT in the emergency department.^[2] Non-contrast CT remains the gold-standard test for stone detection and characterization when more detail is needed — commonly reported sensitivity 95-100% and specificity 94-96%,^[4] with one recent analysis reporting sensitivity as high as 98%, specificity 100%, and a negative predictive value of 97%.^[1] CT also identifies stone size, location, and density (useful for planning definitive treatment — see Non-Pharmacologic Management), and can suggest alternate diagnoses when no stone is found.^[2] Judicious, as-low-as-reasonably-achievable use of CT is advised given the substantial rise in CT utilization for this presentation over the past decade, and low-dose CT protocols preserve diagnostic accuracy while meaningfully reducing radiation exposure.^[2]

Differential diagnosis

Appendicitis, diverticulitis, ovarian torsion or ectopic pregnancy, pyelonephritis, biliary colic, musculoskeletal flank pain, and — genuinely important not to miss in an older patient with flank or back pain, particularly with hypotension — a ruptured or leaking abdominal aortic aneurysm should all be considered.

Metabolic evaluation for recurrent or high-risk stone formers

A first-time stone former without identifiable risk factors for recurrence warrants only a limited metabolic screen (urinalysis with or without urine culture, serum electrolytes/calcium/creatinine, and stone analysis when available) to rule out an underlying systemic disorder.^[3] An in-depth metabolic evaluation (serum studies plus 24-hour urine collection, when practical) is recommended for patients with recurrence risk factors — children, bilateral or multiple stones, recurrent stones (two or more episodes), non-calcium stones, pure calcium phosphate stones, a complicated stone episode (severe acute kidney injury, sepsis, hospitalization), a solitary kidney, renal insufficiency, a relevant systemic disease (gout, inflammatory bowel disease, hyperparathyroidism, renal tubular acidosis, sarcoidosis), an occupation where public safety is at risk, or a family history of kidney stones.^[3] Stones collected by the patient or removed surgically should be submitted for analysis, since composition guides both prevention and future surgical planning, and changes over time in roughly 21% of patients.^[3]

• Relieve acute renal colic pain effectively and promptly, using an NSAID-first approach rather than defaulting to an opioid.
• Identify and urgently escalate a stone causing infection, obstruction with acute kidney injury, or intractable symptoms rather than managing it as routine renal colic.
• Support spontaneous passage where appropriate — most stones, especially smaller ones, will pass on their own with conservative management.
• Use medical expulsive therapy selectively, in patients genuinely likely to benefit (larger distal ureteral stones), through shared decision-making rather than routinely.
• Confirm stone passage objectively rather than relying on symptom resolution alone.
• Refer appropriately for definitive urologic intervention when a stone is unlikely to pass, is causing ongoing obstruction, or when conservative management has failed.
• Reduce recurrence risk with composition-tailored secondary prevention — dietary and fluid measures for everyone, and specific pharmacotherapy (thiazides, potassium citrate, allopurinol) for recurrent stone formers.
• Support adherence to secondary prevention, since compliance with pharmacologic prophylaxis is genuinely poor in practice.

Acute pain management — NSAIDs first, not opioids

1st line an NSAID is genuinely the evidence-preferred first-line analgesic for renal colic, not simply a "safer alternative": NSAIDs (ketorolac is the most-studied parenteral option) are as effective as, or more effective than, opioids, with fewer adverse effects.^[4][1] In a large multicentre randomized trial of 1,500 adult emergency-department patients with renal colic, intramuscular diclofenac reduced pain at 30 minutes by 50% more than intravenous morphine did, with no difference in adverse events.^[2] Avoid meperidine given its comparatively high rate of nausea.^[4] Reserve opioids for breakthrough pain not controlled by an NSAID, or when an NSAID is contraindicated; genuinely moving away from routine opioid use in renal colic is a real, current practice shift worth reinforcing with patients.^[2] An antiemetic (e.g., ondansetron) is a reasonable adjunct for the nausea and vomiting that often accompany renal colic.

Conservative management — most stones pass on their own

Non-operative management is a reasonable first-line approach for most patients presenting with a ureteral stone. Spontaneous passage rates are genuinely size-dependent and, for appropriately selected stones, are high: approximately 86% of kidney stones pass spontaneously overall, and passage is substantially more likely for smaller stones (roughly 90% for stones under 6 mm) than for larger ones (roughly 59% for stones larger than 6 mm).^[4] A meta-analysis of 37 studies similarly found 38-71% spontaneous passage for stones under 4 mm.^[2] Conservative management consists of adequate oral hydration and the analgesia regimen above; forced intravenous hydration specifically to promote stone passage is not supported by the evidence and should be avoided — IV hydration has a role in rehydrating a genuinely hypovolemic patient (e.g., from vomiting), but not as a stone-expulsion strategy in its own right.^[2]

Medical expulsive therapy with tamsulosin

Consider for distal ureteral stones roughly 5-10 mm — this is genuinely where the evidence points: several large randomized trials of alpha-blockers for medical expulsive therapy have been neutral overall, but subgroup analyses and multiple meta-analyses, including a Cochrane review of 67 studies, suggest a real benefit concentrated in larger (5-10 mm), distal stones — improved passage rates (relative risk 1.16), fewer hospitalizations, and no significant change in the need for surgical intervention in the higher-quality, placebo-controlled trials.^[2] Tamsulosin 0.4 mg once daily is the prototypical and most-studied agent, acting by relaxing ureteral smooth muscle to facilitate passage; doxazosin 4 mg daily has also been studied.^[4] Because this evidence base is genuinely mixed rather than uniformly positive, medical expulsive therapy should be offered through shared decision-making — discuss the modest, size-dependent expected benefit against the real, if generally mild, adverse effects.^[2] Counsel explicitly on orthostatic hypotension, as with any alpha-blocker — advise rising slowly from sitting or lying, particularly with the first dose.

Confirming passage and duration of conservative management

Neither resolution of pain nor a patient's report of having passed a stone reliably confirms actual passage — in one study, 6.2% of patients reporting passage of a symptomatic stone had persistent obstruction on follow-up CT, and symptom resolution alone was only 79.7% sensitive and 55.8% specific for confirmed passage on imaging.^[2] Follow-up imaging (typically ultrasound with or without a KUB X-ray) is recommended to confirm passage rather than relying on symptoms alone.^[2] The appropriate duration of a conservative trial is individualized, but surgical intervention should generally be considered if an obstructing ureteral stone has not passed within about 4-6 weeks.^[2]

Secondary prevention — tailored to stone composition

Once the acute episode is managed, preventing recurrence is the next priority for anyone who forms calcium, uric acid, or cystine stones, particularly recurrent stone formers (see Assessment & Diagnosis for who warrants an in-depth metabolic evaluation to individualize this further). Universal dietary and fluid measures apply to everyone (see Non-Pharmacologic Management); composition-specific pharmacotherapy is layered on for recurrent or high-risk stone formers:

• Recurrent calcium stones thiazide diuretics are the primary pharmacologic prevention strategy — they reduce urinary calcium excretion and have been shown in randomized trials to decrease stone recurrence even in patients with normal urinary calcium.^[3] Potassium citrate — not sodium citrate, since a sodium load can itself increase urinary calcium excretion — increases urinary citrate, a natural inhibitor of calcium stone crystallization, and is similarly evidence-supported for reducing recurrence.^[3] Either agent, or ideally both together, also improves bone mineral density and should be considered specifically in stone formers with documented low bone mineral density.^[3]
• Recurrent uric acid stones the first-line strategy is urinary alkalinization to a target urine pH of 6.5, most often achieved with potassium citrate.^[3] Allopurinol is added as adjunctive therapy specifically in patients with confirmed hyperuricemia or hyperuricosuria — it does not add benefit in patients with normal serum uric acid.^[3]
• Calcium stone formers with hypercalciuria and normal uric acid allopurinol is not beneficial here — reserve it for confirmed hyperuricemia or hyperuricosuria.^[3]

See Pharmacologic Treatment Options and Drug Tables for specific agents, doses, and monitoring.

• Fluid intake is the single most important preventive measure for every stone type: counsel all stone formers to target a daily urine output of about 2.5 L (typically requiring roughly 2.5-3 L of fluid intake, more in hot climates or with heavy exercise), which reduces stone recurrence risk by 60-80% in meta-analyses.^[3][4] Water is the first-line fluid; practical strategies include drinking at set times through the day (e.g., with every meal and hourly at work), keeping a water bottle visible, and eating water-rich fruits and vegetables.^[3] Cystine stone formers need a substantially higher target — about 3 L of urine output daily, often requiring 3.5-4 L of fluid intake — since compliance with fluid intake is the single biggest determinant of prevention success in this group.^[3]
• Dietary sodium moderation: limit sodium to about 1500 mg daily and do not exceed 2300 mg daily in patients with recurrent calcium nephrolithiasis, since dietary sodium excess directly increases urinary calcium excretion.^[3]
• Adequate — not restricted — dietary calcium: the goal is 1000-1200 mg/day from diet, ideally in two doses taken with meals (this is when calcium can bind dietary oxalate in the gut and reduce oxalate absorption); calcium supplementation is not required if dietary calcium is adequate, and supplementing outside of meals does not carry the same oxalate-binding benefit.^[3] This is one of the most important — and most counterintuitive — counselling points in this chapter (see Risk Factors).
• Animal protein moderation and avoiding purine-rich foods, for patients with recurrent calcium or uric acid stones.^[3]
• Oxalate moderation for patients with confirmed hyperoxaluria — minimize high-oxalate foods (e.g., spinach, rhubarb, nuts, chocolate); pairing oxalate-containing foods with a calcium source at the same meal helps bind oxalate in the gut before it can be absorbed.^[3]
• A diet high in fiber, fruits, and vegetables offers a small protective effect against stone formation.^[3]
• Avoid vitamin C supplementation above 1000 mg daily, given the associated increase in urinary oxalate and stone risk.^[3]
• Where available, involve a registered dietitian for specific, individualized dietary counselling, particularly for patients with compromised nutritional status or a complex medical picture — patients who receive comprehensive, individualized dietary counselling have fewer recurrences than those given only general advice.^[3]
• Address obesity, diabetes, and metabolic syndrome as part of stone prevention, given their independent association with stone risk (see Risk Factors).^[3]
• For stones unlikely to pass or causing ongoing obstruction, definitive urologic procedures — shockwave lithotripsy and ureteroscopy, with percutaneous nephrolithotomy for large or complex stone burdens — are mainstays of surgical stone management; the choice between them depends on stone size, location, density, and patient factors, and is a urology decision made in partnership with the patient.^[2]

Pregnancy

Ultrasound (abdominal, with or without transvaginal) is the first-line diagnostic test for suspected nephrolithiasis in pregnancy, given the lack of radiation.^[2] If ultrasound is non-diagnostic, magnetic resonance imaging (avoiding gadolinium in the first trimester) can be used, and low-dose non-contrast CT may be considered as an additional option, particularly in the second and third trimesters.^[2] Avoid NSAIDs in pregnancy given known fetal risks — acetaminophen is the preferred analgesic for renal colic pain in pregnancy, with an opioid reserved for pain not controlled by acetaminophen alone.^[2] Data on alpha-blocker medical expulsive therapy in pregnancy are limited: these agents are Category B and appear relatively safe, but efficacy in this population is not well established, so use should be cautious and off-label rather than routine.^[2] Contraindicated shockwave lithotripsy is contraindicated in pregnancy.^[2] If conservative management fails, ureteroscopy with laser lithotripsy has been shown to be safe and effective in pregnancy and can be used both diagnostically and therapeutically.^[2] A ureteral stent or nephrostomy tube, if needed, is at genuinely higher risk of accelerated encrustation in pregnancy and needs more frequent exchange — roughly every 4-6 weeks rather than the usual interval.^[2] Obstructing stones in pregnancy without suspected or confirmed urinary infection can generally be managed conservatively.^[2]

Pediatrics

Pediatric urolithiasis is becoming more common, with incidence increasing by roughly 4-10% annually.^[2] Ultrasound is first-line imaging in children, given radiation concerns, often combined with a KUB X-ray to improve diagnostic accuracy; low-dose non-contrast CT is reserved for select situations.^[2] Unless there is an indication for urgent intervention, a trial of passage of at least two weeks is first-line management for stones smaller than 5 mm.^[2] Medical expulsive therapy is recommended for children with smaller (under 5 mm) stones, with evidence suggesting alpha-blockers are effective and safe in this population, though this remains an off-label use.^[2] When surgical intervention is required, ureteroscopy — using ureteroscopes smaller than 8 French to minimize complications — has consistently outperformed shockwave lithotripsy for mid-to-distal stones in children and is recommended first-line, though shockwave lithotripsy remains a safe, effective option, particularly for proximal stones.^[2] Use weight-based dosing for any analgesic per a current pediatric dosing reference.

Older adults

Maintain a lower threshold to consider a ruptured or leaking abdominal aortic aneurysm in an older patient presenting with flank or back pain, particularly with hypotension — this can closely mimic renal colic. Renal function and comorbidity should guide NSAID choice, dose, and duration.

Renal impairment

Use cautiously or avoid NSAIDs in significant renal impairment, and limit duration when they are used; adjust opioid dosing as needed. Thiazide diuretics become progressively less effective as glomerular filtration rate declines and may not adequately reduce urinary calcium in advanced chronic kidney disease — reassess the prevention regimen with the prescriber in this setting.

Solitary kidney

An obstructing stone in a solitary kidney behaves functionally like bilateral obstruction, since there is no other kidney to maintain renal function — this is a red flag requiring urgent urologic evaluation rather than continued outpatient conservative management (see Red Flags/Refer).

Anticoagulation

Uncorrected coagulopathy is a contraindication to shockwave lithotripsy and antegrade ureteroscopy, given a significantly increased risk of perirenal hematoma and hemorrhagic complications.^[2] When the risk of holding anticoagulation outweighs the benefit of doing so, proceeding with ureteroscopy while the patient remains anticoagulated is an acceptable option in consultation with the prescribing service.^[2]

• For a patient managed conservatively (expectant passage): give explicit return precautions — fever/chills, intractable pain or vomiting, inability to tolerate oral intake, or no urine output — rather than leaving follow-up entirely to the patient's discretion (see Red Flags/Refer).^[2][1]
• Confirm passage with follow-up imaging (typically ultrasound with or without a KUB X-ray) rather than relying on symptom resolution or the patient's report alone, since both are genuinely unreliable confirmatory signs (see Choose Initial Treatment).^[2]
• If a stone has not passed within about 4-6 weeks of conservative management, reassess for surgical intervention rather than continuing indefinite observation.^[2]
• For a patient started on tamsulosin for medical expulsive therapy: continue for up to about 30 days or until confirmed passage; counsel on orthostatic hypotension at initiation.
• For a patient started on thiazide-based secondary prevention: monitor electrolytes (sodium, potassium, glucose, uric acid) periodically, since thiazides can cause dose-dependent hypokalemia, hyperglycemia, hyperlipidemia, hyperuricemia, hypomagnesemia, and hypocitraturia; combining with potassium citrate helps prevent hypokalemia and the hypocitraturia that could otherwise blunt the thiazide's own stone-prevention benefit.^[3]
• For any patient on composition-specific secondary prevention: reassess with repeat 24-hour urine testing roughly every 6 months initially, then annually, to confirm the regimen is working and adjust as needed.^[3]
• Address adherence proactively — this is a genuine, common problem: close to 50% of patients prescribed pharmacologic stone prevention are non-compliant, especially with potassium citrate, despite most patients saying they would prefer prophylactic medication over another stone episode.^[3] A pharmacist is well placed to identify and troubleshoot barriers to adherence at routine follow-up.
• If a new stone forms despite adherence to therapy, submit it for analysis — composition changes in roughly 21% of patients over time, and a change in composition should prompt a change in the prevention strategy.^[3]

1. Obstructing ureteral stone not passed after about 4-6 weeks of conservative management (with or without tamsulosin medical expulsive therapy): refer for surgical intervention (shockwave lithotripsy or ureteroscopy, per stone size, location, density, and urologist judgment) rather than continuing indefinite observation.^[2]
2. New fever, worsening pain, inability to tolerate oral intake, or anuria at any point during conservative management: this is no longer straightforward renal colic — escalate urgently rather than continuing the current plan (see Red Flags/Refer).
3. Inadequate pain control on a scheduled NSAID: add or switch to an opioid for breakthrough pain rather than exceeding safe NSAID dosing; reassess for a complication if pain remains genuinely refractory.
4. Recurrent calcium stones despite thiazide and/or potassium citrate therapy with confirmed adherence: reassess the metabolic evaluation (if not already in-depth) and consider nephrology or urology referral rather than simply continuing an apparently ineffective regimen unchanged.
5. Recurrent uric acid stones despite urinary alkalinization: confirm urine pH is actually reaching the target of about 6.5 and reassess adherence before adding or increasing allopurinol.^[3]
6. Non-adherence to pharmacologic prevention (genuinely common, especially with potassium citrate): explore specific barriers — GI tolerability, pill burden, cost — and consider involving a registered dietitian or simplifying the regimen, rather than assuming the patient does not care about preventing another stone.^[3]

• Reaching for an opioid (or meperidine specifically) first-line for renal colic pain, rather than an NSAID, which is at least as effective with fewer adverse effects.
• Recommending dietary calcium restriction to a stone former — this is a persistent myth that actually increases stone risk by leaving more oxalate free for intestinal absorption; the correct advice is adequate calcium (1000-1200 mg/day) taken with meals.
• Prescribing IV fluids specifically to try to "flush out" a stone faster — forced hydration for this purpose is not supported by the evidence.
• Assuming a stone has passed because pain has resolved or the patient reports passing "something," without confirmatory imaging.
• Using sodium citrate instead of potassium citrate for urinary alkalinization/citrate therapy — the sodium load itself raises urinary calcium excretion, working against the goal.
• Starting allopurinol for uric acid stones without confirming hyperuricemia or hyperuricosuria — it provides no benefit when serum uric acid is normal.
• Treating fever with an obstructing stone as "just a bad episode of colic" rather than recognizing a genuine urologic emergency requiring urgent decompression.
• Overlooking non-adherence as the reason pharmacologic prevention "isn't working" — compliance with prevention, especially potassium citrate, is genuinely poor and worth addressing directly rather than escalating therapy.
• Missing family history and the counterintuitive dietary-calcium point during initial counselling — both are simple, high-yield opportunities.

How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.

Analgesia for Acute Renal Colic

NSAIDs relieve renal colic pain at least as effectively as opioids, with fewer adverse effects — use as first-line therapy rather than defaulting to an opioid.

Opioid Analgesia — Reserve for Breakthrough or Refractory Pain

Genuinely moving away from routine opioid use in renal colic is a current practice shift; reserve for pain not controlled by scheduled NSAID/acetaminophen. Avoid meperidine given its comparatively high rate of nausea.

Antiemetic

For nausea and vomiting accompanying acute renal colic.

Medical Expulsive Therapy — Distal Ureteral Stones Roughly 5-10 mm

Offer through shared decision-making given a genuinely mixed evidence base; benefit is concentrated in larger, distal stones. Counsel explicitly on orthostatic hypotension.

Secondary Prevention — Recurrent Calcium Stones

Thiazide diuretics and potassium citrate are the primary pharmacologic prevention strategies; combining a thiazide with potassium citrate helps prevent thiazide-induced hypokalemia and hypocitraturia. Reassess with repeat 24-hour urine testing roughly every 6 months initially, then annually.

Secondary Prevention — Recurrent Uric Acid Stones

Urinary alkalinization is first-line therapy; allopurinol is adjunctive and reserved for confirmed hyperuricemia or hyperuricosuria.