Objective: Hypoparathyroidism is usually controlled with calcium and vitamin-D supplements; in very few cases this treatment fails and teriparatide may be an alternative. We report the first case of hypoparathyroidism refractory to vitamin-D therapy requiring multipulse teriparatide treatment.
Case report: A 53 year-old woman presented severe hypocalcemia and hypomagnesemia after thyroidectomy. Preoperatively, mild hypercalciuria was detected with parathyroid hormone (PTH) 69 pg/ml (normal 10-45) and 25-OH-vitamin D 9 ng/ml (normal 20-40) and normal levels of magnesium. No response was seen with oral and i.v. calcium and magnesium, or even with 5 microg calcitriol/day, suggesting a vitamin-D resistance status. Calcium sensor and vitamin-D receptor gene mutation studies were negative.
Interventions and results: The following treatments were tried: i) s.c. recombinant human PTH (rhPTH) 1-34 plus oral calcitriol, calcium, and magnesium, was partially effective, but symptoms resumed 4 h after the injection of 20 microg rhPTH; stable calcemia was not achieved even with 4-6 injections/day of teriparatide; ii) two trials of heterologous parathyroid transplant were performed but rejection was detected 3 months after; iii) i.v. magnesium decreased rhPTH requirements but i.m. administration was not tolerated and iv) multipulse s.c. infusion of teriparatide achieved complete normalization of serum calcium, phosphate, magnesium, calciuria and magnesuria with relatively low rhPTH doses (25-35 microg/day) for more than a year.
Conclusions: Vitamin-D unresponsiveness leads to uncontrolled hypocalcemia when postsurgical hypoparathyroidism occurs; in situations of no response to usual or higher doses of vitamin-D and s.c. injections of rhPTH, treatment with teriparatide multipulse s.c. infusor is an effective and safe alternative.