Acute Poststreptococcal Glomerulonephritis

Acute poststreptococcal glomerulonephritis (also called acute glomerulonephritis) is relatively common. This disorder, a bilateral inflammation of the glomeruli, follows a streptococcal infection of the respiratory tract or, less often, a skin infection such as impetigo. It's most common in boys ages 3 to 7 but can occur at any age. Up to 95% of children and 70% of adults recover fully; the rest, especially elderly patients, may progress to chronic renal failure within months.

Causes

• Wegener granulomatosis causes glomerulonephritis that combines upper and lower granulomatous nephritises.
• Hypersensitivity vasculitis encompasses a heterogeneous group of disorders featuring small vessel and skin disease.
• Cryoglobulinemia causes abnormal quantities of cryoglobulin in plasma that result in repeated episodes of widespread purpura and cutaneous ulcerations upon crystallization.
• Systemic lupus erythematosus causes glomerulonephritis through renal deposition of immune complexes.
• Polyarteritis nodosa causes nephritis from a vasculitis involving the renal arteries.
• Henoch-Schönlein purpura causes a generalized vasculitis resulting in glomerulonephritis.
• Goodpasture syndrome causes circulating antibodies to type IV collagen and often results in a rapidly progressive oliguric renal failure.

Signs and Symptoms

Symptoms of APSGN include:

• fluid accumulation and tissue swelling (edema) initially in the face and around the eyes, later in the legs
• low urine output
• blood in the urine
• protein in the urine
• high blood pressure
• joint pain or stiffness

Diagnostic tests

Abnormal blood values (elevated electrolyte, blood urea nitrogen [BUN], and creatinine levels and decreased serum protein levels) and the presence of red blood cells, white blood cells, mixed cell casts, and protein in the urine indicate renal failure. (The proteinuria in an elderly patient usually isn't as pronounced.) Urine frequently contains high levels of fibrin-degradation products and C3 protein.

Elevated antistreptolysin-O titers (in 80% of patients), streptozyme and anti-DNase B titers, and low serum complement levels verify recent streptococcal infection. A throat culture may show group A beta­hemolytic streptococci.

Kidney-ureter-bladder X;rays show bilateral kidney enlargement. A renal biopsy may be necessary to confirm the diagnosis or assess renal tissue status.

Treatment

The goal of treatment in poststreptococcal glomerulonephritis is to eliminate the streptococcal infection with antibiotics and provide supportive therapy until symptoms resolve. The goal of therapy is to relieve symptoms and prevent complications. Vigorous supportive care includes bed rest, fluid and dietary sodium restrictions, and correction of electrolyte imbalances (possibly with dialysis, but this is seldom necessary).

Treatment may include loop diuretics, such as metolazone or furosemide, to reduce extracellular fluid overload, and vasodilators, such as hydralazine or nifedipine. If the patient has a documented staphylococcal infection, antibiotics are recommended for 7 to 10 days; otherwise, their use is controversial.

Prevention

Receiving prompt treatment for streptococcal infections may prevent APSGN.