Long-term intravenous sodium thiosulfate in the treatment of a patient with calciphylaxis.

Calciphylaxis is a disabling and life-threatening complication that primarily affects patients who are dialysis dependent. This disease entity is characterized by calcification, intimal hypertrophy, and thrombosis of small vessels, which results in necrotizing, nonhealing ulcers. The development of these lesions portends a grim prognosis, as they are often accompanied by severe and sometimes fatal infectious complications. Although several strategies aimed at treating and preventing this affliction have been reported in the literature, the outcome for most patients with calciphylaxis remains quite poor. We describe an anuric hemodialysis patient who developed severe calciphylaxis that proved refractory to conventional treatment. Following extensive debridement of several wounds, intravenous sodium thiosulfate was utilized as an adjunctive therapy four times a week. Within 6 months, excellent wound healing ensued as well as a dramatic improvement in the lesions that were not previously resected. Aside from occasional nausea, these treatments were well tolerated, despite the development of an anion gap metabolic acidosis. After 34 months of continued treatment the patient remains free from disease recurrence and has demonstrated no untoward effect of prolonged therapy. In an effort to delineate the pharmacokinetics of this drug in a hemodialysis patient, serum thiosulfate levels were obtained 15 minutes after infusion as well as before and after subsequent dialysis treatments. Consistent with prior studies in anuric canines, we found measurable quantities of the drug more than 50 hours after treatment, in addition to a markedly elevated half life of 478 minutes. However, given the lack of significant toxicity, as well as a dramatic clinical improvement, we feel that sodium thiosulfate may have an important adjunctive role in the treatment of calciphylaxis in dialysis patients.