A 58-year-old woman with end-stage renal disease on hemodialysis for 6 years presents with sudden onset of intensely painful violaceous reticular patches on her abdomen and thighs, progressing to stellate purpuric plaques with black eschar formation over 2 weeks. She is on warfarin for atrial fibrillation. Labs show PTH 920 pg/mL, serum calcium 10.2 mg/dL, phosphate 6.8 mg/dL (Ca × PO4 product 69). Skin biopsy reveals medial calcification of dermal arterioles with intimal hyperplasia and microthrombi. The condition marked **B** in the diagram is suspected. Which of the following is the MOST APPROPRIATE first-line intervention to reduce pain and promote wound healing in this patient?
A. Discontinuation of warfarin and initiation of apixaban
B. Aggressive surgical debridement of necrotic tissue with skin grafting
C. Immediate parathyroidectomy for PTH >800 pg/mL
D. Sodium thiosulfate 25 g IV during the last hour of dialysis, 3 times per week
Explanation
Why Sodium thiosulfate is right
Sodium thiosulfate (25 g IV during the last hour of dialysis, 3×/week) is the FIRST-LINE, evidence-based treatment for calciphylaxis (calcific uremic arteriolopathy, marked B). It acts as a calcium chelator, promotes vasodilation, and provides antioxidant effects. KDIGO 2017 and NEJM reviews emphasize that early sodium thiosulfate dramatically reduces pain and improves wound healing outcomes in dialysis patients with calciphylaxis. This patient's presentation—intensely painful skin lesions, medial calcification on biopsy, elevated Ca × PO4 product, and ESRD on dialysis—is pathognomonic for calciphylaxis, and sodium thiosulfate is the cornerstone of acute management.
Why each distractor is wrong
Immediate parathyroidectomy: While parathyroidectomy is indicated for severe secondary hyperparathyroidism (PTH >800 pg/mL) refractory to medical therapy, it is NOT first-line and requires weeks to months for surgical planning and recovery. Sodium thiosulfate provides immediate pain relief and must be started urgently before considering surgery.
Discontinuation of warfarin and initiation of apixaban: Although warfarin should be discontinued (it inhibits matrix Gla protein, a calcification inhibitor) and anticoagulation switched to apixaban or LMWH, this is a supportive measure, not the primary therapeutic intervention. It does not directly address the acute calciphylaxis pathology or provide rapid pain relief.
Aggressive surgical debridement with skin grafting: Debridement is explicitly contraindicated in calciphylaxis because it worsens necrosis and triggers Koebnerization. Wound care should be conservative (maggot therapy, negative pressure therapy, hyperbaric oxygen). Aggressive surgery increases morbidity and mortality.
High-YieldNEET PG
In any dialysis patient with NEW-ONSET, EXQUISITELY PAINFUL skin lesions with medial calcification, start sodium thiosulfate IMMEDIATELY—it is first-line and life-saving.
