Rapid resolution of calciphylaxis with intravenous sodium thiosulfate and continuous venovenous haemofiltration using low calcium replacement fluid: case report.

The pathogenesis of calciphylaxis (calcific uremic arteriolopathy) remains to be fully elucidated, which makes treatment of this often fatal disease quite challenging. While controversial, vascular calcium deposition may play a secondary, if not primary, role in ongoing tissue ischemia. In cases that would not benefit from early parathyroidectomy, alternative strategies have been proposed to control calcium and phosphate homeostasis. The use of non-calcium based phosphate binders and intermittent haemodialysis with low calcium dialysate [1,2] has been of benefit in some but not all patients. One of the most recently suggested therapies is the use of sodium thiosulfate to increase the solubility of calcium deposits [3]. With its reported success in treating both nephrolithiasis [3] and tumoral calcinosis [4,5], Cicone et al. [6] described its efficacy when given after haemodialysis treatments in a single case of calciphylaxis. We hypothesized that the benefits of solubilizing calcific deposits in patients with ESRD would be severely limited by calcium clearance being dependent on intermittent dialysis sessions. To optimize removal, we devised a regimen combining intravenous sodium thiosulfate treatment with continuous venovenous haemofiltration (CVVH): a constant state of mild hypocalcaemia was maintained by a regimen involving zero-calcium replacement fluid, regional citrate anticoagulation and protocol-driven calcium repletion. We report here a case of progressive biopsy-proven calciphylaxis that responded rapidly to this new approach and which had an excellent outcome.