Rapid regression of calciphylaxis in a hemodialysis patient after intensive management of disturbance of calcium and phosphate metabolism: a case report with literature review

Background Calciphylaxis, a multifactorial cutaneous vascular disease, is a rare but therapy-resistant and life-threatening disorder that usually occurs in patients with end-stage kidney disease (ESKD). Although there have been many reports regarding calciphylaxis, its pathophysiology is not fully understood and strong evidence for its treatment is lacking. Case presentation A 63-year-old woman with a 20-year history of hemodialysis (HD) for ESKD of unknown etiology was admitted because of severe painful cutaneous ulcers on the right lower leg. She underwent artificial heart valve replacement surgery for infective endocarditis 13 years earlier, following which warfarin was prescribed. Laboratory findings on admission showed elevation of the calcium (Ca)-phosphorus (P) product due to hyperphosphatemia, and parathyroid hormone (PTH) levels were above the target range. Additionally, the efficiency of HD, based on Kt/V urea, was reduced because of vascular access (VA) failure. Furthermore, there was no evidence of inflammation, and the ankle-brachial index was within the normal range. Skin biopsy specimens showed thrombosis of the small vessels and marked Ca deposition in the media of the arterioles, which were compatible with a diagnosis of calciphylaxis. Hence, in addition to surgical repair of VA failure and prolongation of HD treatment time, we discontinued administration of the synthetic vitamin D3, calcitriol, and switched treatment from cinacalcet to etelcalcetide, which is a novel peptide agonist of the Ca-sensing receptor. Consequently, serum Ca, P, and Ca-P product levels decreased immediately, although her PTH levels remained high. Her painful severe skin ulcers regressed completely within 3 months. Conclusion In this patient, although the influence of oral warfarin therapy and secondary hyperparathyroidism, which are known risk factors for calciphylaxis, was not removed, her ulcers appeared to respond to the optimization of disturbed Ca-P metabolism. Our experience suggests that intensive management of serum Ca and P levels is essential to prevent the development of calciphylaxis. Hypercalcemia and hyperphosphatemia due to excess vitamin D receptor activators could be risk factors for calciphylaxis.