Cinacalcet in hyperparathyroidism secondary to X-linked hypophosphatemic rickets: case report and brief literature review

Abstract

X-linked dominant hypophosphatemic rickets (XLH) is the most prevalent genetic form of hypophosphatemic rickets. standard treatment of XLH patients includes long-term administration of phosphate and calcitriol. Treated patients usually respond well to the conventional therapy and demonstrate amelioration of rachitic symptoms and improved growth. However, long-term administration of phosphate and vitamin D preparations is sometimes complicated with nephrocalcinosis, secondary or tertiary hyperparathyroidism and arterial hypertension. We describe a patient with XLH, caused by a rare missense mutation of the PHEX gene. The patient, while under treatment with alphacalcidol and oral phosphate, developed hypercalciuria, nephrocalcinosis, secondary hyperparathyroidism and arterial hypertension. cinacalcet was added to the therapeutic regimen and the long-term effects on calciotropic parameters and FGF23 levels are herein reported.

Post-surgery severe hypocalcemia in primary hyperparathyroidism preoperatively treated with zoledronic acid

“…10 A recent report described the first case of hungry bone syndrome induced by therapy based on Cinacalcet, a calcimimetic agent approved for the treatment of secondary hyperparathyroidism. 11,12 It is suggested that the hypocalcemia in our patient occurred because BP therapy effectively reduced osteoclastic bone resorption, while osteoblastic bone formation persisted. In other words, the failure to correct the postoperative hypocalcemia was due to the intense anti-resorptive action of zoledronic acid in bone which blocked the mobilization of calcium from the skeleton.…”

Clinical practice

“…Furthermore, phosphate supplements, which may cause a decrease in ionised calcium and a compensatory increase in PTH concentration, may partially be responsible [22]. Recently, the possibility of the use of calcimimetics (cinacalcet) in controlling hyperparathyroidism in XLH has been considered [2,28]; however, there are no formal trials reported utilising this adjuvant therapy.…”

Other Secondary Hyperparathyroid States

“…80 Furthermore, sustained decreases in circulating FGF23 have been observed in a case report of one patient with XLH and secondary hyperparathyroidism who was successfully treated with cinacalcet. 81 Secondary hyperparathyroidism that arises from treatment of XLH with phosphate supplements may progress to tertiary hyperparathyroidism with autonomous hyperfunction of the parathyroids. This propensity for secondary and tertiary hyperparathyroidism has been reported in several hundred patients treated for XLH.…”