Normal serum complement levels would be seen in patients with hematuria, proteinuria, and hypertension resulting from which of the following?
**Core Concept**
Normal serum complement levels are expected in patients with hematuria, proteinuria, and hypertension resulting from conditions that do not involve complement system activation. This is because the complement system is a part of the innate immune response that helps eliminate pathogens and damaged cells by promoting inflammation and cell lysis.
**Why the Correct Answer is Right**
The correct answer is IgA nephropathy, also known as Berger's disease. This condition is characterized by the deposition of IgA antibodies in the glomeruli, leading to inflammation and damage. However, the complement system is not activated in IgA nephropathy, which is why serum complement levels remain normal. The pathogenesis of IgA nephropathy involves the abnormal production and deposition of IgA antibodies in the glomeruli, which leads to the activation of various immune cells and the release of pro-inflammatory cytokines.
**Why Each Wrong Option is Incorrect**
**Option A:** Post-streptococcal glomerulonephritis (PSGN) - This condition is caused by an immune response to streptococcal infections and typically involves the activation of the complement system, leading to decreased serum complement levels.
**Option B:** Membranous nephropathy - This condition is characterized by the thickening of the glomerular basement membrane due to immune complex deposition, which can activate the complement system and lead to decreased serum complement levels.
**Option C:** Lupus nephritis - This condition is an autoimmune disease that involves the activation of the complement system, leading to decreased serum complement levels.
**Clinical Pearl / High-Yield Fact**
IgA nephropathy is the most common cause of recurrent hematuria, particularly in young adults, and is often associated with respiratory infections.
**Correct Answer:** C.