A Headache Beyond the Brain: Cerebral Venous Sinus Thrombosis Revealing IgA Nephropathy

Abstract

IgA nephropathy commonly presents with haematuria and subnephrotic proteinuria, while nephrotic syndrome and extra-renal thrombotic complications are rare. We report a 49-year-old man with no prior medical illness who presented with a two-week history of thunderclap headache, frothy urine, and peripheral oedema. Investigations revealed severe hypoalbuminaemia, nephrotic-range proteinuria, hypercholesterolaemia, and preserved renal function. Neuroimaging demonstrated cerebral venous sinus thrombosis. Renal biopsy confirmed IgA nephropathy (Oxford classification M0 E0 S1 T0 C0). This case highlights an atypical presentation of IgA nephropathy complicated by cerebral venous sinus thrombosis secondary to nephrotic syndrome–associated hypercoagulability. It underscores the importance of recognising thunderclap headache as a red flag for cerebral venous sinus thrombosis in nephrotic patients and the role of early renal biopsy in establishing diagnosis despite negative serological workup.