Nephrolithiasis (kidney stones)
Crystalline stones formed in the urinary tract. Affects 10% of men and 7% of women lifetime, often with recurrence. Severe flank pain radiating to groin is the classic presentation; lab workup separates calcium-oxalate (most common) from uric-acid, struvite and cystine subtypes.
What it is
Kidney stones are crystalline aggregates that form when urinary supersaturation, low inhibitors (citrate, magnesium), and stagnant urine combine. Composition determines workup and prevention: calcium-oxalate (~75%, the textbook stone), calcium-phosphate (10%, alkaline urine), uric-acid (10%, acidic urine, gout patients), struvite (5%, urease-producing UTIs), cystine (<1%, hereditary). Risk factors: low water intake, high-sodium / high-protein diets, obesity, type 2 diabetes, hyperparathyroidism, gout, inflammatory bowel disease (enteric hyperoxaluria), and family history. Acute presentation is renal colic — sudden severe flank pain radiating to the groin or testicle / labia, often with vomiting and microscopic haematuria.
Key lab markers
- Serum calcium — high suggests primary hyperparathyroidism (the most actionable underlying cause).
- PTH — if calcium is high, PTH distinguishes parathyroid vs malignant hypercalcaemia.
- Uric acid — high → suspect uric-acid stones (especially with gout, acidic urine).
- Creatinine, eGFR — kidney function; obstruction can cause acute kidney injury.
- 24-hour urine collection (after first stone, definitely after second) — measures volume, calcium, oxalate, citrate, uric acid, sodium, pH; the gold standard for prevention planning.
- Stone analysis — every recovered stone should go to the lab.
Symptoms
- Severe colicky flank pain radiating to groin / testicle (renal colic)
- Nausea, vomiting (often from referred pain, not GI)
- Macroscopic or microscopic haematuria
- Urinary urgency, frequency once stone enters lower ureter
- Fever (suggests obstruction + infection — emergency)
- Asymptomatic 'silent' stones found on imaging for another reason
When to discuss with a doctor
Acute renal colic warrants emergency-department assessment for analgesia, imaging (CT KUB is the gold standard), and exclusion of infected obstruction (sepsis risk). Stones <5 mm typically pass spontaneously; >10 mm need urology (lithotripsy, ureteroscopy). Every stone-former should have first-stone workup: serum calcium, PTH if calcium high, uric acid, full metabolic, and a 24-hour urine 4-6 weeks after the acute event. Mediora.AI flags the (high calcium + high uric acid + recurrent stones) cluster; prevention planning (diet, medication, fluid targets) is nephrology / urology.