What key symptom is associated with IgA nephropathy following respiratory infections?

• A. Peripheral edema
• B. Oliguria
• C. Episodic hematuria
• D. Nephrotic syndrome

Answer: (C)

The key symptom associated with IgA nephropathy following respiratory infections is episodic hematuria. This condition is characterized by the presence of blood in the urine, which often occurs after an upper respiratory tract infection. Patients may notice that their urine appears red or dark after experiencing these infections, which coincides with the immune response triggered by the infection.

IgA nephropathy, also known as Berger's disease, involves the deposition of IgA antibodies in the glomeruli, leading to inflammation and damage to the kidney structures. The timing of the hematuria is a crucial aspect, as it typically follows infections, highlighting the relationship between respiratory illness and the onset of renal symptoms.

Other symptoms like oliguria, peripheral edema, and nephrotic syndrome can be associated with various other kidney conditions, but they are not the defining hallmark of IgA nephropathy. In contrast, episodic hematuria specifically aligns with the pathophysiology of IgA nephropathy, making it the most relevant key symptom in this context.