An Unusual Presentation of IgA Vasculitis and IgA Nephropathy: A Case Report.

Immunoglobulin A (IgA) nephropathy is the most common glomerulonephritis worldwide. While IgA nephropathy mainly presents with renal manifestations, systemic symptoms associated with vasculitis are uncommon. Oftentimes, creatinine is used as a serum marker for renal dysfunction; however, it may not always be sensitive, especially in patients with low muscle mass. In such cases, cystatin C may prove to be a better indicator of renal function. Here, we present a case of IgA nephropathy with a normal serum creatinine and elevated cystatin C, highlighting the utility of cystatin C in the setting of a normal creatinine and high suspicion for renal dysfunction.