How do systemic diseases such as scleroderma and lupus affect the kidneys?

• A. Scleroderma has no renal involvement; lupus nephritis is not immune complex mediated.
• B. Scleroderma renal crisis does not involve hypertension; lupus nephritis is immune complex mediated.
• C. Scleroderma affects only the skin; lupus nephritis affects only the lungs.
• D. Both Scleroderma renal crisis and lupus nephritis involve kidney pathology; scleroderma renal crisis can cause abrupt hypertension and renal failure, whereas lupus nephritis is due to immune complex deposition causing glomerulonephritis.

Answer: (D)

Systemic autoimmune diseases can hit the kidneys through different pathways, so kidney involvement is a key feature in both scleroderma and lupus. In scleroderma, a renal crisis can develop suddenly with abrupt high blood pressure and a rapid rise in kidney failure, driven by microvascular injury in the kidneys and activation of the renin–angiotensin system. In systemic lupus erythematosus, kidney damage is typically lupus nephritis caused by immune complex deposition in glomeruli, which triggers complement activation and inflammatory damage to the glomeruli. So both diseases affect the kidneys, but by distinct mechanisms: scleroderma renal crisis presents with sudden hypertension and renal failure, whereas lupus nephritis is an immune complex–mediated glomerulonephritis. The other statements misstate either the presence of renal involvement or the underlying mechanism.