IgA nephropathy with rheumatoid arthritis related to adalimumab.

The co-occurrence of rheumatoid arthritis (RA) and IgA nephropathy (IgAN) is rare, presenting diagnostic and therapeutic challenges, particularly regarding potential associations with therapies such as TNF inhibitors. We report the case of a 44-year-old man diagnosed with seronegative RA following evaluation for polyarthritis. His prior treatments included rituximab and etanercept, although specific details were unavailable. Adalimumab therapy, initiated in 2014, effectively controlled his RA symptoms for five years. However, in 2019, he developed progressive proteinuria (1 g/day), persistent microscopic hematuria, and low C3/C4 levels. A kidney biopsy revealed IgAN (Oxford classification M1, E0, S1, T1, C0). Suspecting a temporal association with adalimumab, the medication was discontinued, resulting in a significant decrease in proteinuria (to 0.1 g/day) and normalization of serum creatinine. Subsequent treatment with tofacitinib provided inadequate RA control. In 2021, certolizumab was initiated, leading to sustained improvement in RA symptoms (DAS28-CRP 2.6) and continued remission of IgAN (proteinuria 0.2 g/day). This case highlights the potential association between adalimumab use and the development of IgAN in patients with RA and underscores the importance of vigilant renal monitoring during TNF inhibitor therapy.