A 52-year old woman suffering from diabetes mellitus and frequent urinary tract infection presented with marked flank pain, fever and general malaise. Urine cultures revealed more than 100,000 colonies and a mixed flora composed predominantly of gram negative microorganisms. Blood pressure was 170/110 mm Hg. Urea nitrogen was 50 mg/dl (normal 20 mg), creatinine 3 mg/dl (normal less than 1.5 mg). Serum glucose was 160 mg/dl (normal = 75-115 mg/dl). Urine contained 2+ sugar, 1+ protein and the sediment contained neutrophils and occasional hyalin casts. On X-rays one kidney appeared small and shrunken and the pelvis and calices appeared dilated.

Note the irregular scarring of the surface.

In diabetic patients, the tips of papillae may undergo ischemic necrosis and may be sloughed off into the urine. Diabetes predisposes to urinary tract infections and these predispose to urolithiasis. Urinary stones may interfere with the discharge of urine and may cause hydronephosis.

Chronic pyelonephritis is a well-known cause of hypertension. Changes in the blood vessels are indistinguishable from those produced by "idiopathic" hypertension. Note the "onion-skin" appearance of the vessel wall.

Question for Class Discussion