A patient develops gross hematuria 3 days after an attack of UI.Which of the following is responsible:

Ans. D: IgA nephropathyThe classic presentation (in 40-50% of the cases) of Ig A nephropathy is episodic frank hematuria which usually stas within a day or two of a non-specific upper respiratory tract infection (hence synpharyngitic) as opposed to post-streptococca glomerulonephritis which occurs some time (weeks) after initial infection.All of these infections have in common the activation of mucosal defenses and hence IgA antibody production.The gross hematuria resolves after a few days, though microscopic hematuria may persist.These episodes occur on an irregular basis every few months and in most patients eventually subside (although it can take many years).Renal function usually remains normal, though rarely, acute renal failure may occur.This presentation is more common in younger adults.