Acute Proliferative Glomerulonephritis

The most commonly recognized form of acute nephritjcsyndrome is diffuse proliferative glomerulonephritis, which follows infections caused by strains of group A 3-hemolytic streptococci. Diffuse proliferative glomerulonephritis may also occur after infections by other organisms, including staphylococci and a number of viral agents, such as those responsible for mumps, measles, and chickenpox. With this type of nephritis, the inflammatory response is caused by an immune reaction that occurs when circulating immune complexes become entrapped in the glomerular membrane. Proliferation of the endothelial cells lining the glomerular capillary (i.e., endocapillary form of the disease) and the mesangial cells lying between the endothelium and the epithelium follows (see Fig. 28—7). The capillary membrane swells and becomes permeable to plasma proteins and blood cells. Although the disease is seen primarily in children, adults of any age can also be affected. 

The classic case of poststreptococcal glomerulonephritis follows a streptococcal infection by about 10 days to 2 weeks—the time needed for the development of antibodies. Oliguria, which develops as the GFR decreases, is one of the first symptoms. Proteinuria and hematuria follow because of increased glomerular capillary wall permeability. The blood is degraded by materials in the urine, and a cola-colored urine may be the first sign of the disorder. Sodium and water retention give rise to edema, particularly of the face and hands, and hypertension. Important laboratory findings include an elevated streptococcal exoenzyme (antistreptolysin O) titer, a decline in C3 complement (see Chapter 11), and cryoglobulins (i.e., large immune complexes) in the serum. 

Treatment for acute poststreptococcal glomerulonephritis is largely symptomatic. The acute symptoms  usually begin to’ subside in about 10 days to 2 weeks, although in some children, the proteinuria may persist for several months. The immediate prognosis is favorable, and about 95% of children recover spontaneously. The outlook for adults is less favorable; about 60% recover completely. In the remainder of cases, the lesions eventually resolve, but there may be permanent kidney damage.