複数の要因によって発現したと考えられるⅣ型尿細管性アシドーシスを呈した糖尿病性腎症の1剖検例

Abstract

We report a case of diabetic nephropathy and type Ⅳ renal tubular acidosis in a 65-year-old woman. She was admitted to our hospital because of unstable angina pectoris and was found to have severe metabolic acidosis and hyperkalemia. She gave a history of non-insulin-dependent diabetes mellitus beginning when she was 39 years old, rheumatoid arthritis at 60 years, and hypertension at 64 years of age. Laboratory data on admission were as follows : sodium, 129 mEq/l ; potassium, 8.2 mEq/l ; chloride, 111 mEq /l ; bicarbonate, 14.5 mEq/l ; and creatinine clearance, 61 ml/min. Bicarbonate loading test revealed that FEHC03 was 0.043%, and U-BPC02 was 12 mmHg. Renin-aldosterone system responded poorly to a furosemide loading test. Renal biopsy revealed diabetic nephropathy (diffuse Ⅲ) and interstitial fibrosis. At the age of 66 years, the patient underwent coronary artery bypass grafting. At age 71, she died of acute myocardial infarction (AMI). Autopsy findings included AMI, arteriosclerosis, and diabet- ic nephropathy (diffuse Ⅲ, nodular Ⅱ). In this case, we speculated that type Ⅳ renal tubular acidosis developed as a result of impairment of tubular potassium excretion induced by attenuated responsiveness to aldos- terone (pseudohypoaldosteronism), hyporeninemic hypoaldosteronism, and drug therapy (a nonsteroidal anti-inflammatory drug and an ACE inhibitor).