Bone Abstracts

Background: Pediatric hypoparathyroidism is an orphan disease. Conventional management combines native and active vitamin D, calcium supplementation and sometimes phosphate binders. The use of teriparatide has been reported both in adults (daily or bi-daily subcutaneous infusions) and in children (rather continuous subcutaneous infusion) as second-line therapy.

Methods: We present as median (min-max) the results of a retrospective single-centre review of medical charts of all children receiving teriparatide in our centre from 06/2016 to 12/2018.

Results: At a median age of 11.2 (3.7–15.5) years, Schwartz eGFR 109 (85–205) ml/min per 1.73 m², calcium 1.88 (1.62–2.17) mmol/l, phosphate 2.39 (1.74–2.79) mmol/l thus corresponding to SDS of 3.9 (1.1–5.6), 25-D 81 (47–112) nmol/l, teriparatide therapy was introduced in nine patients at the dose of 20 μg twice daily (1.04 (0.45–1.48) μg/kg/day), with further adjustment depending on calcium levels. Eight of them directly received intermittent supplementation when one patient briefly received continuous teriparatide infusion with a switch to intermittent supplementation after 4 months. The causes of hypoparathyroidism were CaSR mutation (n=4), APECED syndrome (n=2), post-surgical hypoparathyroidism due to Cowden syndrome (n=1), Di George syndrome (n=1) and hypoparathyroidism of unknown etiology (n=1). With a median follow-up of 1.4 (0.4–2.4) years, all patients still receive teriparatide. Severe side effects were reported in one child, namely two episodes of severe hypocalcemia and one of iatrogenic hypercalcemia. Other side effects were milder (lumbar pain, moderate hypocalcemia and dysgueusia). At the last follow-up, teriparatide dose was reduced in 6 children; median age was 11.8 (5.3–17.7) years, Schwartz eGFR 94 (79–162) ml/min/1.73m², calcium 1.98 (1.80–2.20) mmol/l, phosphate 1.9 (1.5–2.2) mmol/l thus corresponding to SDS of 2.1 (−1.1 to 3.16) (P<0.01), and 25-D 66 (35–119) nmol/l. Calciuria and calcium/creatinine ratio remained stable. On the renal ultrasounds, neither nephrolithiasis nor nephrocalcinosis appeared. Among children with pre-existing nephrocalcinosis, one worsened from stage 1 to 2, whilst the other two remained stable. Five children required the reintroduction of low doses of vitamin D analogs.

Conclusion: Intermittent teriparatide therapy decreases phosphatemia with a better control of calcemia and without any changes in calciuria. Thus, it appears to be a safe option in children refractory to conventional treatment. Long-term larger studies are required to confirm these data.

Disclosure: The authors declared no competing interests.