Nejm 2009;359:1477; 2004;350:151

Cause:Genetic, autosomal dominant; at least 2 different gene sites (Nejm 1988;319:913), most commonly (90%) on chromosome 6; rare (1/20 000) autosomal recessive type

Pathophys:Tubular cysts increase in size by secretion of solutes and compromise renal function (Nejm 1969;281:985), thereby increasing renin-aldosterone systems, which cause hypertension (Nejm 1990;323:1091); also occur in liver

Most diagnosed in early adulthood although infantile type does occur and presents as large kidneys at birth, causing death within months. Peak onset at age 45 yr; 100% get by age 90 yr; female-to-male ratio equal; prevalence = 1/400-1000

Sx:Flank/back pain (61%); positive family hx (60%); dysuria (8%); gross hematuria (12%); nocturia (8%); headache (20%); nausea (5%)

Si:Hypertension (62%); palpable kidney (52%); palpable liver (27%); abdominal tenderness (20%); peripheral edema (10%); systolic murmur (10%)

5-10 yr after BUN starts to increase

Hepatic cysts (40%), increasing incidence with age; also in pancreas and spleen; berry aneurysm (4%), screen pts w family h/o aneurysm w CT or MRI and operate if >10 mm (Nejm 1992;327:916, 953); aortic and mitral valve dilatations (Nejm 1988;319:907); Na wasting, occasionally renal tubular acidosis

r/o other renal cystic disease (Ann IM 1978;88:176):

• Multicystic renal disease, which consists of benign, common retention cysts
• Multicystic dysplasia: compatible with life if unilateral, most not hereditary, associated with urethral atresia, rarely autosomal dominant and associated w deafness and hypoparathyroidism (Nejm 1992;327:1069)
• Medullary cystic disease (Nejm 2004;350:151) with anemia, severe Na wasting, renal failure, and death in teens; autosomal dominant
• Medullary sponge kidney with tubular ectasia, benign except for stones and pyelo, worst in women (Nejm 1982;306:1088), small stones in cysts (r/o nephrocalcinosis and tbc), associated with Ehlers-Danlos syndrome, also with autosomal recessive renal-retinal dysplasia with retinitis pigmentosa (Ann IM 1976;84:157);
• Hypokalemia-induced medullary cysts, reversible (Nejm 1990;322:345)

Lab:

Chem:BUN and creatinine increase late in course

Path:Dilated nephrons and tubules lead to cysts

Urine:AM specific gravity <1.015; proteinuria, pyuria

Xray:

IVP shows large cystic kidneys

Ultrasound is most sensitive test, and can look for hepatic cysts too (40%); most abnormal by age 20 yr in carriers

Rx:

of renal failure

Tight BP control may retard progression, ACE inhibitors can be used cautiously but precipitate acute renal failure (Ann IM 1991;115:769); avoid catheterization at all costs since can lead to rapidly fatal infection; avoid hypokalemia, which can increase cyst growth rate

Occasionally need surgical relief of pressure from bloody cystic compression of adjacent structures