After consultation with the patient, an off-label use of STS was decided on. STS was infused through a central venous line after HD sessions at a dose of 25 g 3 times during the first week and then at a dose of 12.5 g 3 times per week for 3 months in total. No significant side effect was noted. The skin lesions had significantly resolved (fig. (fig.1b).1b). Before treatment, the patient's plasma calcium level was 2.67 mmol/l, and his plasma phosphorus and iPTH levels were 3.02 mmol/l and 1,577 pg/ml, respectively. At the end of treatment, the plasma calcium level was 2.38 mmol/l, and his plasma phosphorus level was 2.77 mmol/l and the iPTH level 2,310 pg/ml. The calcium-phosphorus product had decreased slightly over the 3 months of therapy with some increase in the iPTH level (fig. (fig.22).