Urinary Stones – Top USMLE Diseases

Nephrolithiasis is the formation of a stone, or calculus, anywhere along the urinary tract caused by precipitations of solutes in the urine. The most common type of kidney stone is the calcium oxalate stone, but other types include calcium phosphate, struvite (ammonium magnesium phosphate), uric acid, and cystine stones. Nephrolithiasis presents with colicky flank pain, which radiates to the groin, and hematuria due to damage to the ureters. Diagnosis is made by noncontrast CT of the abdomen and pelvis or by renal ultrasound, and urinalysis is performed to exclude concomitant urinary tract infection (UTI). Management depends on the size of the stone. Small stones likely to pass on their own are managed conservatively with hydration and analgesics. Large stones unlikely to pass spontaneously are managed with extracorporeal shock wave lithotripsy (ESWL), ureterorenoscopy, or percutaneous nephrolithotomy. Nephrolithiasis can be complicated by hydronephrosis or acute pyelonephritis. Adequate hydration is the best prophylactic intervention to prevent kidney stones.