Transplant Renal Artery Stenosis Presenting as Posterior Reversible Encephalopathy Syndrome in a Post-Kidney Transplant Patient: A Case Report

Transplant renal artery stenosis (TRAS) is a reversible cause of severe hypertension and graft dysfunction. Posterior reversible encephalopathy syndrome (PRES) in kidney transplant recipients is commonly attributed to calcineurin inhibitor (CNI) toxicity; however, the biochemical signatures of CNI toxicity and TRAS differ markedly. We report a 32-year-old woman, five months post-transplant, presenting with seizures, severe hypertension, and MRI-confirmed PRES. She exhibited hypokalaemia (2.6 mmol/L) and metabolic alkalosis (pH 7.50, bicarbonate 34 mmol/L)— findings less typical of tacrolimus toxicity, which more typically produces a Gordon-like physiology with hyperkalaemia and metabolic acidosis due to excess activity of the NCC (Na-Cl cotransporter). Doppler ultrasound and digital subtraction angiography confirmed TRAS. Percutaneous angioplasty resulted in rapid renal recovery. PRES with hypokalaemia should prompt evaluation for renovascular hypertension rather than tacrolimus toxicity.