[Translated article] Multicenter retrospective analysis of sodium thiosulfate as treatment for non-uremic calciphylaxis

Objectives

To describe the results obtained in terms of effectiveness and safety of intravenous sodium thiosulfate in patients diagnosed with non-uremic calciphylaxis, to identify and analyse possible etiological factors of the disease, and to determine the associated morbidity and mortality.

Method

A multicenter and retrospective study was conducted with patients diagnosed with non-uremic calciphylaxis who received intravenous sodium thiosulfate between 2013 and 2023. Effectiveness was evaluated based on the status of the ulcers at the end of treatment, and safety was assessed according to the main reported adverse effects and the need for dosage adjustment.

Results

A total of 33 patients from three university hospitals were evaluated (93.9% Caucasian, 78.8% women, mean age 80 [SD 8.1] years) with non-uremic calciphylaxis confirmed by skin biopsy. The localization pattern was 90.9% distal. The following complementary therapeutic measures were undertaken: topical wound care, removal of precipitating factors (mainly vitamin D supplements and vitamin K antagonists), medications to reduce calcification (bisphosphonates, cinacalcet), and techniques to promote ulcer healing. The main associated factors for developing calciphylaxis were: non-uremic chronic kidney disease (81.8%), vitamin D supplementation (72.7%), and hypoalbuminemia (66.7%). The most commonly used sodium thiosulfate dosage was 25 g (n = 26) three times per week (n = 28) intravenously, with a median treatment duration of 11.4 (IQR 5.7-18) weeks. A complete resolution or improvement of the ulcers was achieved in 78.8% of the cases. Adverse effects were observed in 96.7% of patients, with the most common being metabolic acidosis (n = 19) and nausea and/or vomiting (n = 18). Dosage adjustments due to toxicity were necessary in 9% of cases. The significant morbidity rate was 69.7% (n = 23). The main complications were: 57.6% ulcer superinfection and 24.3% poor pain control. The overall mortality rate was 66.7%; 42.4% within the first 6 months after diagnosis and 39.4% secondary to non-uremic calciphylaxis.

Conclusions

Sodium thiosulfate shows a potential benefit in the treatment of ulcers due to non-uremic calciphylaxis, with a similar safety profile to that reported for uremic calciphylaxis, considering the high morbidity and mortality associated with the condition. Further studies are needed to determine its efficacy and assess the specific contribution of the different treatments used.