Internal Medicine

Answer 3 Diffuse proliferative glomerulonephritis. Based on this patient’s 24-hour urine collection (1500 mg protein) and renal biopsy results, she has diffuse proliferative glomerulonephritis, or World Health Organization (WHO) class IV disease. The WHO classifies lupus nephritis into 5 categories based on histology and location of the immune complexes. In WHO class I, the kidney is considered normal; there is no immune complex deposition or bland urine sediment, and 24-hour urine collection yields proteinuria less than 200 mg. WHO class II (mesangial nephritis) is characterized by immune complex deposition only in the mesangium. Red blood cells may be present in the urine sediment or the sediment may be bland. The 24-hour urine collection reveals proteinuria ranging from 200 to 500 mg. WHO class III (focal segmental glomerulonephritis) is characterized by mesangial and subendothelial immune complex deposition, urine sediment that includes both red blood cells and white blood cells, and proteinuria ranging from 500 to 3500 mg on 24-hour urine collection. In patients with class III disease, serum creatinine and blood pressure may be normal to mildly elevated. Testing for anti- dsDNA antibodies is positive and C3/C4 levels are decreased. WHO class IV (diffuse proliferative glomerulonephritis) consists of mesangial and subendothelial immune complex deposition. The urine sediment is filled with red blood cells, white blood cells, and red blood cell casts. The 24-hour urine collection reveals proteinuria ranging from 1000 to 3500 mg. Serum creatinine ranges from normal to extremely elevated to the extent that the patient is dialysis-dependent. Patients with class IV disease are usually hypertensive, have low serum complement levels, and test positive for anti-dsDNA antibodies.3 In WHO class V (diffuse membranous glomerulonephritis), global or segmental subepithelial deposits are present. The urine sediment is bland, 24-hour urine collection demonstrates more than 3000 mg of protein, serum creatinine is normal to mildly elevated, and blood pressure is normal. REFERENCE 3. Hricik D, Chung-Park M, Sedor JR. Glomerulonephritis. N Engl J Med 1998;339:889-97. Click here to return to the questions

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