Glomeruli are tiny spherical structures in the kidneys, made of capillaries, where the blood is filtered to produce urine. Glomerulonephritis occurs when the glomeruli become inflamed and are unable to function normally. Acute glomerulonephritis can develop suddenly. Chronic glomerulonephritis may set in over a period of time. Glomerulonephritis can occur on its own or in connection with diabetes or lupus. Severe or prolonged glomerulonephritis could cause permanent loss of function in the kidneys.