Endocrine Abstracts

Background: Hypoparathyroidism is an endocrine disorder characterized by hypocalcemia due to low levels of parathyroid hormone (PTH). Activated vitamin D (calcitriol) and calcium supplementation may be difficult in patients with malabsorption, as calcium requires an acid environment to dissolve. In this setting, subcutaneous administration of PTH analogues may be effective in reducing the dosage of oral calcium and vitamin D supplementation.

Case report: A 36-year-old woman with a history of sleeve gastrectomy and Single Anastomosis Duodeno-Ileal switch was diagnosed with papillary thyroid carcinoma and referred to total thyroidectomy. After surgery, she presented paresthesia, undetectable PTH, calcium 6.5 mg/dl and TSH was normal, so an oral regimen of calcium carbonate 1 gr tid and calcitriol 0.5 mcg tid was started without resolution. She came several times both to our Endocrinology Unit and to the emergency department due to symptomatic hypocalcemia. Therefore, oral treatment was gradually increased up to calcium carbonate 9 gr and calcitriol 4 mcg per day, and then intravenous calcitriol and calcium gluconate infusion was started. However, this did not allow complete resolution of hypocalcemia and the patient experienced some discomfort mainly due to gastrointestinal symptoms. Symptoms began to worsen after several weeks. At this moment, in Italy, RDNA PTH (1–84) is not refunded by the national health service. For that, after patient’s consent, treatment with rhPTH (1–34 – teriparatide) analogue 20 mcg/day was started with no adverse reaction. Soon, we were able to significantly reduce the dosage of calcium carbonate to 2 gr and calcitriol 2.5 mcg/day. After fifty days of this treatment calcium was 8.5 mg/dl. Recently the dose of teriparatide was titrated to 40 mcg/day, with further reduction of oral treatment, and the patient has not had any symptoms related to hypocalcemia.

Conclusion: First-line of treatment in hypoparathyroidism is activated calcitriol and calcium supplementation maintain low-normal calcium levels, to prevent hypocalcemia and avoid hypercalcemia and renal calcification. Gastric bypass or duodenal resection can increase the risk of hypocalcemia, as they cause malabsorption. As alternative options intravenous calcium, calcitriol infusion and rhPTH should be considered to maintain normal calcium levels. Even when the patient is stabilized, episodes of hypocalcemia may occur, so careful monitoring is still required. To date, this is the second reported case of the use of a PTH analogue to treat hypoparathyroidism with good calcium control in a patient who underwent bariatric surgery.