Glomerulonephritis

A syndrome characterized pathologically by diffuse inflammatory changes in the glomeruli and clinically by hematuria with red blood cell casts, mild proteinuria, and, often, hypertension, edema, and azotemia.

The important types of glomerulonephritis in the elderly are acute (postinfectious) glomerulonephritis and glomerulonephritis associated with systemic disease or an unknown cause.

Acute (postinfectious) glomerulonephritis: In the past, glomerulonephritis was usually caused by streptococcus; currently, glomerulonephritis is increasingly caused by staphylococcal and gram-negative bacteria. However, streptococcus is still the cause in a greater proportion of elderly patients. Often, these infections occur in immunocompromised persons (eg, alcoholics, diabetics, IV drug abusers).

Symptoms vary considerably by age. In elderly patients, nonspecific symptoms are typical (eg, nausea, malaise, arthralgias, a striking early predilection for pulmonary infiltrates) and suggest worsening of a preexisting illness, especially heart failure. About 75% of elderly persons have renal failure at presentation, with 20% requiring dialysis. Although the prognosis is generally good in younger patients with poststreptococcal disease, it is much less favorable in elderly patients, especially those with renal failure at presentation. The likelihood of progression to chronic glomerulonephritis, which is characterized ultimately by hyalinization of glomeruli, increases with age. Treatment with corticosteroids, immunosuppressants, anticoagulants, and plasmapheresis is generally considered to be of little value and confers a high risk.

Glomerulonephritis associated with systemic disease or an unknown cause: The cause is often an immunologic reaction to a systemic disease (eg, lupus erythematosus, vasculitis, Wegener's granulomatosis) or a primary renal disease of unknown etiology (eg, rapidly progressive [crescentic] glomerulonephritis with or without glomerular immune deposits). Symptoms are similar to those observed with acute postinfectious glomerulonephritis except that onset may be more chronic. Symptoms may also result from the underlying systemic disease (eg, upper and lower respiratory tract symptoms resulting from the necrotizing vasculitis of Wegener's granulomatosis). Diagnosis should include measurements of serum antinuclear antibodies (ANA), serum antibodies to specific antineutrophil cytoplasmic autoantibodies (p- and c-ANCA), serum complement, and serum and urine electrophoresis. In about half of patients with crescentic glomerulonephritis and a positive p-ANCA test but no other evidence of systemic disease, early treatment with high-dose pulse corticosteroid therapy has been shown to stabilize or improve renal function.