Background: Activating mutations in the calcium sensing receptor can result in severe hypoparathyroidism with symptomatic hypocalcaemia. Complications of treatment with calcitriol or alfacacidol include hypercalciuria, nephrocalcinosis and renal failure. The use of synthetic parathyroid hormone (PTH 134, teriparatide) provides a more physiological treatment option and reduces the risk of hypercalciuria. Intermittent injections of PTH have been used with some success but we report our experience of the first UK child treated with a continuous s.c. infusion of PTH (CSIP).
Presenting Problem: A 1-year-old girl presented with hypocalcaemic convulsions and was found to have hypoparathyroidism due to an activating mutation of the calcium sensing receptor (CaSR) (c.2528C>A, p.A843E). She was initially treated with alfacalcidol but continued to have episodes of symptomatic hypocalcaemia. After informed discussion, eucalcaemia was successfully achieved with twice daily s.c. injections of PTH. Her requirements slowly increased and after 3 years, she was requiring 75 μg daily in three divided injections, almost twice the recommended adult dose. To reduce the total dose of PTH and the need for multiple daily injections, CSIP was commenced using an insulin infusion pump to deliver the PTH at a constant rate throughout the day and night.
Clinical management: Baseline plasma calcium was 2.2 mmol/l. PTH 134 was infused initially at a rate of 72 μg/day (equivalent to the dose being received by injection) but she rapidly became hypercalcaemic. 72 h after starting the infusion, her total dose had been reduced by 50% and her calcium stabilised.
Discussion: PTH administered via CSIP significantly reduced the total daily dose, indicating that this more effective than multiple s.c. injections. She no longer required multiple injections and only needed to change her giving set every 3 days. We recommend that this is the treatment of choice in cases such as these.
13 Nov 2013
British Society for Paediatric Endocrinology and Diabetes