Nephrolithiasis
Nephrolithiasis affects 7-11% of the US population, most often as calcium oxalate stones, and presents as colicky flank pain radiating to the groin with hematuria. Noncontrast CT confirms the diagnosis and stone size drives management: hydration, NSAID/opioid analgesia, and alpha-blocker expulsive therapy for stones under 10 mm, urologic intervention for larger, infected, or obstructing stones.
- Topic reviewThe full article, organized the way the exam asks it.
- ABIM-format MCQsVignettes with an explanation for every wrong answer.
- Key factsThe numbers and thresholds worth memorizing, up front.
- AI tutorMedBrain answers the question you're stuck on.
What this article covers
- Overview
A common, frequently recurrent disease: nephrolithiasis is stone (calculus) formation within the urinary tract.
- Epidemiology
7% to 11% lifetime prevalence in the United States, with a 50% rate of recurrent disease after a first stone.
- Risk factors
Male sex, older age, and White race: the strongest demographic risk factors.
- Pathophysiology
Supersaturation of urine with stone-forming solutes is the common final pathway: when a solute exceeds its solubility in urine, it precipitates and aggregates into a stone.
- Clinical features
Colicky flank pain radiating to the groin is the hallmark: waxing and waning severe pain with constant shifting to find a comfortable position, unlike the still posture of peritonitis.
- Differential diagnosis
Pyelonephritis: distinguished by fever, systemic toxicity, and pyuria/bacteriuria as the dominant findings rather than colicky pain; can coexist with an obstructing infected stone, which changes management urgency.
- Diagnosis
Nephrolithiasis is confirmed by imaging demonstrating a calculus; there is no formal clinical criteria set, so the diagnosis rests on the clinical picture (colicky flank pain radiating to the groin…
- Management
First, treat pain and facilitate diagnosis in every symptomatic patient: Ketorolac 30 mg IV once, then 15-30 mg IV every 6 hours as needed (max 5 days cumulative therapy), for first-line analgesia.
- Complications
Obstructive uropathy with acute kidney injury: most dangerous when bilateral or in a solitary kidney.
- Prognosis
Most small stones pass spontaneously with expulsive therapy: stones under 5 mm usually pass on their own, and roughly half of stones under 10 mm pass with alpha-blocker or calcium channel blocker therapy, generally within 2 weeks.
- Prevention
Increase fluid intake to a urine output target above 2500 mL/day (above 3000 mL/day for cystine stone formers), the single most important intervention to prevent recurrence regardless of stone type.
Read the whole article
Subscribing to Internal Medicine opens every article, the full question bank and MedBrain, on the web, iPhone and Android.
Related articles
- Approach to hematuria
Hematuria is present in urine when at least 3 erythrocytes per high-power field are seen on microscopy, and the first branch point is glomerular versus nonglomerular bleeding, based on erythrocyte morphology and casts. Gross hematuria always requires urologic evaluation and cystoscopy, asymptomatic microscopic hematuria is risk-stratified by American Urological Association criteria to select repeat testing, imaging, or cystoscopy, and glomerular hematuria is treated with disease-specific immunosuppression after biopsy.
- Acute kidney injury
Acute kidney injury is a sudden rise in serum creatinine or fall in urine output from prerenal, intrinsic, or postrenal causes, defined and staged by KDIGO criteria. Management targets the underlying cause, corrects volume and electrolyte derangements, and escalates to renal replacement therapy for refractory hyperkalemia, acidosis, volume overload, or uremia.
- Chronic kidney disease
Chronic kidney disease is abnormal kidney structure or function present for more than 3 months, staged by the Kidney Disease: Improving Global Outcomes (KDIGO) system using estimated glomerular filtration rate and albuminuria, and managed with blood pressure control, renin-angiotensin blockade, an SGLT2 inhibitor, and correction of its metabolic complications.
- Benign prostatic hyperplasia (BPH)
Benign prostatic hyperplasia is age-related epithelial and stromal growth of the prostate transition zone causing bladder outlet obstruction and lower urinary tract symptoms in older men. Diagnosis rests on history, the AUA/IPSS symptom score, and a symmetrically enlarged, smooth prostate on digital rectal exam; management is staged from observation to alpha-1-blockers, 5-alpha-reductase inhibitors, and surgery.