Calciphylaxis in Predialysis CKD: Improvement with Sodium Thiosulfate

Introduction: Calciphylaxis is a rare, life-threatening disorder marked by thrombosis of small- to medium-sized vessels, causing painful necrotic skin lesions. Though typically linked to dialysis-dependent end-stage kidney disease (ESKD), non-uremic calciphylaxis(NUC) is increasingly noted in early CKD, transplant recipients, and warfarin users. Due to limited data, treatment remains inconsistent. We describe two NUC cases in pre-dialysis CKD that improved with sodium thiosulfate (STS). Case Description: Case 1: A 72-year-old man with CKD G3b-A3, diabetes, coronary disease, hypertension, and past warfarin use presented with a chronic leg ulcer and worsening kidney function. Imaging and biopsy confirmed calciphylaxis. He received IV STS, titrated up to 25g twice weekly for seven months, resulting in wound healing and radiologic improvement. Case 2: A 68-year-old woman with CKD G3a-A2, diabetes, hypertension, atrial fibrillation and chronic warfarin use developed a biopsy confirmed right leg ulcer. Warfarin was replaced with apixaban, and STS was started at 25g IV thrice weekly. The lesion resolved in three months but recurred contralaterally after STS was stopped, requiring re-initiation. Discussion: These cases highlight the utility of STS in treating calciphylaxis in non-dialysis CKD.Up to 20% of cases occur in non-ESKD settings and are often underdiagnosed. Early diagnosis and STS initiation may prevent tissue loss. Reporting such cases clinical enhances awareness and evidence-based care.Case-1: *Pre-STS; # Post-STSCase-2: *Pre-STS; # Post-STS Table-1 - Labs Case-1 Case-2 Serum Calcium 8.3 mg/dl 9.3 mg/dl Serum Parathyroid Hormone 108 pg/ml 52 pg/ml