Gorlin-Bushkell-Jensen syndrome: A rare disorder characterized by the development of numerous sebaceous cysts (mainly on the back, chest, arms, thighs and scrotum) as well as kidney stones and white nails.
* Sebaceous cysts * Kidney stones * White nails
Although the exact cause of renal calculi is unknown, predisposing factors include: * Dehydration: Decreased urine production concentrates calculus-forming substances. * Infection: Infected, damaged tissue serves as a site for calculus development; pH changes provide a favorable medium for calculus formation (especially for magnesium ammonium phosphate or calcium phosphate calculi); or infected calculi (usually magnesium ammonium phosphate or staghorn calculi) may develop if bacteria serve as the nucleus in calculus formation. Infections may promote destruction of renal parenchyma. * Obstruction: Urinary stasis (as in immobility from spinal cord injury) allows calculus constituents to collect and adhere, forming calculi. Obstruction also promotes infection, which, in turn, compounds the obstruction. * Metabolic factors: These factors may predispose to renal calculi: hyperparathyroidism, renal tubular acidosis, elevated uric acid (usually with gout), defective metabolism of oxalate, genetic defect in metabolism of cystine, and excessive intake of vitamin D or dietary calcium. Among Americans, renal calculi develop in 2% to 10% of the population, with people living in southeastern states having an increased risk. They’re more common in males (especially those ages 30 to 40) than in females by a 3:1 ratio. They’re rare in children. Some types of calculi tend to be familial; some are associated with other conditions, such as bowel disease, ileal bypass for obesity, or renal tubule defects. Calcium calculi are most common, accounting for over 75% of all calculi, and are two to three times more common in males, usually appearing between ages 20 and 30. The calcium may combine with other substances, such as oxalate (the most common substance), phosphate, or carbonate, to form the stone. Oxalate is present in certain foods. Diseases of the small intestine increase the tendency to form calcium oxalate calculi. Recurrence is likely. Uric acid calculi are also more common in males and make up about 6% of all calculi. These calculi are associated with gout and chemotherapy. Cystine calculi, which make up about 2% of all calculi, may form in people with cystinuria, a hereditary disorder affecting both males and females. Struvite calculi, accounting for about 15% of all calculi, are mainly found in females as a result of a urinary tract infection (UTI). They can grow very large and may obstruct the kidney, ureter, or bladder. Indavir stones appear in patients with human immunodeficiency virus who are treated with the protease inhibitor indinavir.
Because 90% of renal calculi are smaller than 5 mm in diameter, treatment usually consists of measures to promote their natural passage. Along with vigorous hydration, such treatment includes antimicrobial therapy (varying with the cultured organism) for infection, analgesics such as meperidine for pain, and diuretics to prevent urinary stasis and further calculus formation (thiazides decrease calcium excretion into the urine). Prophylaxis to prevent calculus formation includes a low-calcium diet for absorptive hypercalciuria, parathyroidectomy for hyperparathyroidism, allopurinol for uric acid calculi, and daily administration of ascorbic acid by mouth to acidify the urine. Calculi too large for natural passage may require surgical removal. When a calculus is in the ureter, a cystoscope may be inserted through the urethra and the calculus manipulated with catheters or retrieval instruments. Extraction of calculi from other areas (kidney calyx, renal pelvis) may necessitate a flank or lower abdominal approach. Percutaneous ultrasonic lithotripsy and extracorporeal shock wave lithotripsy shatter the calculus into fragments for removal by suction or natural passage.