Chronic glomerulonephritis: Nonimmunologic mechanisms of progressive glomerular damage

Patient]. A 66-year-old man was first evaluated in the Renal Clinic of the New England Medical Center (NEMC) at age 53. At age 9, he developed periorbital and peripheral edema, gross hematuria, cylindruria, and proteinuria. He was told he had acute glomerulonephritis and was confined to bed for one month; the edema and hematuria resolved. He remained asymptomatic for the next four decades although urinalyses performed during Army and insurance examinations consistently revealed trace to I + protein. At the age of 53, he noted intermittent pedal edema over a 3-month period. Physical examination revealed a blood pressure 130/90 mm Hg. The ocular fundi were normal. Cardiovascular examination was unremarkable. No abdominal organomegaly was present. There was 1 + pittingedema of the feet. Urinalysis revealed a specific gravity of 1.012, a pH of 5, no sugar, 1 + protein, 3 to 5 red blood cells per high-power field, no white blood cells, and rare granular casts. Twenty-four hour urine protein excretion measured on three occasions ranged between 400 and 900 mg; no significant postural component to the protein excretion was evident. Urine culture was sterile. The serum albumin was 4.5 ing/dI. The serum creatinine was 1.1 mg/dl and the BUN was 17 mg/dl. The patient was believed to have 'latent glomerulonephritis' for which no specific therapy was recommended. His edema resolved spontaneously during the next several weeks. During the ensuing 13 years, serial measurements of serum creatinine revealed a slowly progressive decline in renal function (Table I). During this period, urinalyses continued to reveal 1+ to 3+ protein and occasional red blood cells. The patient developed mild hypertension, treated initially with alpha-methyldopa, and later with propranolol. The latter drug was discontinued 2 years ago because of mild hyperkalemia (serum potassium 5.8 mEq/liter); however, the serum potassium concentration remained in the range of 5.0 to 5.4 mEq/liter subsequently. Because of recent increasing fatigue, intermittent nausea, and pruritus, plans are being made to initiate chronic hemodialysis. Patient 2. A 44-year-old woman was first admitted to NEMC 12 years ago because of acute renal failure. Three weeks earlier she had complained of a mild sore throat lasting only a few days. One week before admission she noted fever, palpitation, and painful erythematous lesions and swelling over the anterior lower legs. Physical examination at another hospital disclosed mild pharyngitis, erythema nodosum, and tachycardia. Blood pressure was 134/82 mm Hg. Neither a heart murmur nor edema was noted. An electrocardiogram revealed nonspecific T-wave abnormalities, and p-hemolytic streptococcus was recovered from a throat culture. The BUN was 12 mg/dl, and a urinalysis revealed no protein and 2 to 3 red blood cells per high-power field. Acute rheumatic fever was diagnosed, and treatment with erythromycin and aspirin was begun. Fever, tachycardia, and cardiac abnormalities improved, but edema developed. After 5 days, the urine output suddenly ceased. The BUN rose swiftly to 117 mg/dl and the serum creatinine increased to 4.7 mg/dl. The patient was transferred to NEMC for further evaluation and treatment. Her first pregnancy had been complicated by hypertension and postpartum hemorrhage 10 years earlier. She denied a history of renal disease, hypertension, diabetes, urinary tract infection, renal calculi, or hematuria. She was allergic to penicillin. Physical examination revealed a blood pressure of 120/70 mm Hg; mild periorbital, sacral, and ankle edema; and erythema nodosum. Urinalysis demonstrated 3+ protein, many red blood cells, and 3 to 4 red blood cell casts. Serum complement (C3) was subnormal; ANA and LE preps were negative. Nephrotomography demonstrated 15.5 cm kidneys. She was treated with peritoneal dialysis, oral Kayexalate,5 and a Giovanetti diet. An open renal biopsy 2 days later revealed diffuse, exudative, and proliferative glomerulonephritis typical of acute poststreptococcal glomerulonephritis. During the next 3 weeks, the patient remained anuric and required 2 peritoneal dialyses. Despite normal blood pressure (110 to 140/70 to 90 mm Hg), papilledema occurred. The neurologic examination was otherwise normal. One month after her illness began, urinary volume progressively increased and she noted less fatigue. Renal function improved and peritoneal dialysis was discontinued. Blood pressure rose to 150/115 mm Hg and therapy with alpha-methyldopa was begun. After another month, the BUN had fallen to 11 mg/dl and the serum creatinine to 1.1 mg/dl. During the next 2 months she continued to feel well, and her renal function remained normal. Hypertension persisted; the urinary sediment contained 50 to 75 red blood cells per high-power field and occasional red blood cell and granular casts. Urinary protein excretion declined from 4.7 to 2.3 g daily. A second renal biopsy revealed onethird of the glomeruli to be hyalinized, with more than one-half normal or only slightly sclerotic. No cellular proliferation or exudation remained. Hyaline droplet degeneration of proximal tubular cells and protein casts within tubules were evident. The biopsy was interpreted as revealing chronic, inactive proliferative glomerulonephritis.