Idiopathic Nephrotic Syndrome in a 53-Year-Old Woman Is a Kidney Biopsy Necessary?

nephrotic syndrome. Nine years earlier, she had been found to have a blood pressure of 150/110 mmHg. At that time her 24 hour protein excretion was 900 mg, her blood urea nitrogen was 18 mg/dl, and her serum creatinine was 0.9 mg/dl. She was given propranolol and achieved good control of her blood pressure. One year before admission her protein excretion increased to 2.8 grams/24 hours and her serum creatinine was 1.1 mg/dl. At that time both the antinuclear antibody titer and the lupus erythematosus preparation were negative; serum protein electrophoresis, serum complement (C3) and intravenous pyelogram were normal. Four months before admission the patient noticed periorbital and ankle swelling. Physical examination revealed a blood pressure of 180/95 mmHg, pedal edema, but no other phy-sical abnormalities. Laboratory tests revealed a protein excretion of 4.5 grams/24 hours, serum albumin of 3.8 grams/dl, serum creatinine of 1.1 mg/dl, and elevated serum lipids. Protein selectivity (the ratio of urinary transferrin to IgG concentration) was 0.15. Urinalysis revealed microscopic hematuria. A diagnosis of idiopathic nephrotic syndrome (INS) was made. The Division of Clinical Decision Making was asked to review the conven-tional diagnostic strategy of performing a renal biopsy, and to consider whether empiric therapy with corticosteroids might be a reasonable alter-native