Endocrine Abstracts

Context: Teriparatide may represent a possible treatment for hypoparathyroidism when oral supplementation with calcium and calcitriol fail to maintain adequate serum calcium level (SCL). The switch from teriparitide to oral calcium and calcitriol could be challenging and there is no consensus for clinical management.

Case presentation: A 50-year-old man was admitted at our Department for teriparatide discontinuation. Three years before admission, the patient underwent total thyroidectomy for a multinodular goiter. Three months after thyroidectomy, the patient was admitted to the intensive care unit for the onset of symptomatic hypocalcemia. Laboratory exams were consistent with hypocalcemia related to post-surgical hypoparathyroidism. The patient was discharged with calcium carbonate and calcitriol therapy but in the following months the patient was re-admitted several times to the E.R. for the recurrence of symptomatic hypocalcemia. Therefore in addition to the oral therapy, teriparatide was introduced. After two years of treatment, teriparatide has been discontinued in accordance to the national drug administration (AIFA) authorizing regulations. At the admission, the physical examination was normal. Laboratory exams were notable for low SCL and an elevated serum TSH level despite high dose of Levothyroxine supplementation (250 mcg/d). After teriparatide discontinuation SCL progressively decreased (6,5 mg/dl) with the onset symptoms of hypocalcemia, despite high doses of calcium carbonate and calcitriol. Further investigations revealed an atrophic autoimmune gastritis, confirmed at gastroscopy. It was decided to switch from calcium carbonate to calcium citrate and to modify patient’s diet. SCL slowly increased up to 8,6 mg/dl so that the patient could be discharged. In six months, no symptomatic hypocalcemia occurred and the SCL were stable with oral therapy.

Conclusions: Teriparatide discontinuation in patients treated for hypoparathyroidism is challenging and clinically does not differ from “hungry bone syndrome” after parathyroidectomy. Furthermore calcium citrate could be an alternative to calcium carbonate in patients with achlorhydria.