Which glomerulonephritis is classically associated with low serum complement levels?

Which glomerulonephritis is classically associated with low serum complement levels?

• A. IgA nephropathy
• B. Minimal change disease
• C. Post-infectious glomerulonephritis
• D. FSGS

Answer: (C)

Low serum complement levels reflect consumption of complement by immune complex–mediated injury in the glomerulus. Post-infectious glomerulonephritis, often following a streptococcal infection, is driven by immune complexes that activate the classical complement pathway, causing a drop in C3 (with normal C4 in many cases) that resolves over weeks as the infection clears. This pattern—low C3 with recovery over time—helps distinguish it from other glomerulonephritides where complement levels are usually normal. IgA nephropathy commonly presents with normal complement, and minimal change disease or focal segmental glomerulosclerosis do not feature hypocomplementemia as a hallmark of their pathophysiology.

Low serum complement levels reflect consumption of complement by immune complex–mediated injury in the glomerulus. Post-infectious glomerulonephritis, often following a streptococcal infection, is driven by immune complexes that activate the classical complement pathway, causing a drop in C3 (with normal C4 in many cases) that resolves over weeks as the infection clears. This pattern—low C3 with recovery over time—helps distinguish it from other glomerulonephritides where complement levels are usually normal. IgA nephropathy commonly presents with normal complement, and minimal change disease or focal segmental glomerulosclerosis do not feature hypocomplementemia as a hallmark of their pathophysiology.