Calciphylaxis (calcific uremic arteriolopathy, uremic small-artery disease with medial calcification and intimal hyperplasia, vascular calcification–cutaneous necrosis syndrome, calcifying panniculitis) is a serious and often lethal condition affecting mostly patients with renal disease. Calciphylaxis may be considered the cutaneous equivalent of myocardial infarction. Medial calcification and subintimal fibrosis of arterioles result in arteriolar stenosis. This is followed by thrombotic occlusion and cutaneous necrosis. Calciphylaxis can present either with tender subcutaneous plaques, or skin ulcers reflecting various stages of the progression of the disease process.
Monitoring the patient’s metabolic environment is of utmost importance. Hyperphosphatemia must be controlled with non-calcium containing phosphate binders. Phosphorus-restricted diet should be introduced, and vitamin D supplementation stopped. Discontinuation of warfarin due to its proposed procoagulant effect is paramount. Aggressive wound debridement needs to be initiated without delay. Monitoring for infection and appropriate use of antibiotics are a mainstay of treatment, since most patient deaths occur from sepsis.
Intravenous sodium thiosulfate recently emerged as a promising new treatment for calciphylaxis. This medication is currently used as an antidote for the treatment of cyanide poisoning and prevention of toxicity in cancer therapies. The mechanism of action is believed to be chelation of calcium resulting in dissolution of calcium deposits. Additionally, sodium thiosulfate appears to act as an antioxidant, reducing damage from intravascular reactive oxygen species. The evidence in favor of sodium thiosulfate is limited to multiple case reports. Yet, it appears to be safe and non-toxic, and therefore deserves a trial as a first line therapy for calciphylaxis.
Bisphosphonates are another group of medications that alone or in combination with sodium thiosulfate are emerging as an important part of calciphylaxis treatment. They are thought to inhibit local proinflammatory cytokines and decrease arterial calcification.
Cinacalcet may also be used for patients with elevated parathyroid hormone. This medication is believed to act by reducing serum parathyroid hormone and stabilizing calcium and phosphate levels. It is useful in patients with elevated parathyroid hormone levels. Parathyroid hormone should be monitored throughout the treatment to minimize the risk of adynamic bone disease associated with cinacalcet therapy.
The use of zero or low-calcium dialysate with induction of hypocalcemia and calcium shift into intravascular space appears to be a reasonable therapy. If hyperbaric oxygen therapy is available, it can be very helpful to some patients.
Parathyroidectomy, which improves calcium, phosphate, and parathyroid hormone levels, is a useful therapy for those patients with high parathyroid hormone levels. Despite being a subject of controversy, for many patients this surgery results in rapid healing of ulcerations. In many cases the use of cinacalcet avoids parathyroidectomy.
The treatment of calciphylaxis should be a multidisciplinary effort with internists, critical care specialists, nephrologists, dermatologists, infectionists, surgeons, and pain specialists being involved.