Nephrolithiasis

NEPHROLITHIASIS • 12 percent of men and 5 percent of women will have at least one symptomatic stone by the age of 70. • Male - 2 times more common, middle-aged white men

Types Calcium oxalate/phosphate: 60-80% Struvite (triple phosphate): 5-15% Uric Acid: 5-10% Cystine: 1% Other (xanthine, indinavir etc): 1%

Risk Factors Dietary: Low fluid intake, High sodium intake, High protein intake, Low calcium intake Metabolic:Hypercalciuria, Hypocitraturia, Hyperuricosuria, Hyperoxaluria Medical Conditions: Gout, Obesity, Renal tubular acidosis, Sarcoidosis, Primary hyperparathyroidism, Medullary sponge kidney, Horseshoe kidney, HIV/AIDS with protease inhibitors, Metabolic syndrome/type 2 diabetes mellitus Genetic: Polycystic kidney disease, Dent's disease, Cystinuria, Primary hyperoxaluria

Clinical features Urinary tract symptoms • Pain—classic colicky loin to groin pain or renal pain, • Haematuria, gross or microscopic (occurs in 90%) • Dysuria Systemic symptoms • Restless patient, often writhing in distress, • Nausea, vomiting• Fever and chills (if associated infection) Asymptomatic • Incidental stones (one third may become symptomatic) - The likelihood of developing symptoms was approximately 32 percent at 2.5 years and 49 percent at 5 years

Diagnosis Urinalysis in patients with nephrolithiasis reveals blood, and the urine sediment has intact, nondysmorphic erythrocytes. * The majority of kidney stones are radio opaque and visualized on kidney, ureter, and bladder film. * Renal ultrasonography detects kidney stones and urinary tract obstruction but is less sensitive for smaller stones. * Intravenous pyelography is highly sensitive and specific for kidney stones but is contraindicated in patients with renal insufficiency. * Noncontrast helical abdominal CT is the gold standard for diagnosing nephrolithiasis.

In a patients with recurrent stones, in addition to the baseline investigations (U/A, BMP), consider PTH, Vit D, a 24 hour urine assessment for urine volume and calcium, oxalate, uric acid, citrate, urine sodium, and creatinine excretion.

Treatment Hydration and pain control with NSAIDS or narcotics if renal insufficiency is present in the acute setting. Kidney stones <5 mm in diameter typically pass spontaneously, whereas stones >10 mm often require invasive measures Shock wave lithotripsy, ureteroscopy, and percutaneous nephrolithotomy have replaced open surgery for treating urolithiasis Most simple renal calculi (80-85%) can be treated with shock wave lithotripsy Percutaneous nephrolithotomy is the treatment of choice for complex renal calculi Staghorn calculi should be treated, and percutaneous nephrolithotomy is the preferred treatment in most patients Ureteroscopy is the preferred treatment in pregnant, morbidly obese, or patients with coagulopathy

Prevention 15% have recurrence at 1 year, 35% to 40% at 5 years, and 50% at 10 years Fluid consumption >2 L/d and restriction of sodium intake Targeted therapy is recommended for patients with an identifiable metabolic abnormality that favors stone formation

Quiz ______________ (alone or in combination) is the most common type of urinary stone. Most ureteral stones under ________ pass spontaneously. ______________ is the most common abnormality and the single most important factor to correct so as to avoid recurrences.