Calcific uremic arteriolopathy (CUA) or calciphylaxis is a condition predominantly observed in patients with end-stage kidney disease characterized by small vessel calcification, intimal proliferation, endovascular fibrosis and intravascular thrombosis causing down-stream infarction predominantly of skin resulting in extremely painful necrotic ulceration. Several interventions have been proposed in an attempt to attenuate the high mortality associated with CUA. One of the most promising therapeutic approaches is the administration of sodium thiosulfate which is able to chelate cations such as calcium and in this way possibly dissolving tissue calcium deposits into more hydrophilic calcium thiosulfate. Due to the scarcity of reports of CUA patients treated with sodium thiosulfate the safety profile of this drug is not (well) established at this moment especially in patients not receiving kidney replacement therapy. Here, we describe a case of a kidney transplant recipient with CUA and moderately declined kidney function who was treated with sodium thiosulfate and developed important hypernatremia and high anion gap acidosis necessitating significant reduction in dosing.