Continuous Subcutaneous PTH Infusion in Autosomal Dominant Hypocalcaemia

Presentation Number: OR06-3
Date of Presentation: April 4th, 2017

Evelien F Gevers*1, Jaccqui Buck2, Neil Ashman3, Rajesh V Thakker4 and Jeremy Allgrove5
1William Harvey Research Institute / Barts Health NHS Trust, London, United Kingdom, 2Ipswich Hospital, Ipswich, United Kingdom, 3Barts Health NHS Trust, London, United Kingdom, 4University of Oxford, Oxford, United Kingdom, 5Great Ormond Street Hospital, London, United Kingdom

Abstract

Autosomal Dominant Hypocalcaemia (ADH) is due to gain-of-function mutations of the CASR resulting in constitutive activation of the GPCR Calcium Sensing Receptor (CaSR) leading to hypercalciuric hypocalcaemia, hypoparathyroidism and occasionally Bartter syndrome type V. Patients usually present with hypocalcaemic seizures at young age. Conventional treatment is with Alfacalcidol and Calcium or PTH injections. We describe a series of 5 patients with ADH in whom stabilization of calcium concentrations could not be achieved with conventional treatment and in whom continuous subcutaneous PTH infusion (CSPI) using insulin pumps was started.

CaSR mutations were P.Thr828Asn, not previously described, and the previously described p.Ala843Glu, p.Tyr829Cys, p.Phe821Leu. Patients presented with hypocalcaemic seizures or tetany in the first few weeks of life. Additional features were bilateral cataracts, hypomagnesaemia, Bartter type V. One patient had nephrocalcinosis before CSPI. Age at start of CSPI was 3 weeks, 6 weeks, 6 months, 6 years and 20 years. Medtronic and Omnipod patch pumps were used to deliver diluted PTH(1-34). Treatment was started in an inpatient setting. Duration of treatment is currently 1-3 years. PTH requirement was 0.21, 0.13, 0.15, 0.5 and 3 mcg/kg/day. Four patients required Magnesium supplementation. All patients received Cholecalciferol. Calcium concentration stabilised and patients continue to require weekly or bi-weekly blood tests. Number of admissions significantly reduced during CSPI. Seizures stopped in all patients on CSPI. Current calcium concentrations range from 1.75-2.15mmol/l. Current urine Calcium/creat ratios range from 1.2 to 2.5 mol/mol. Nephrocalcinosis has remained stable. One patient stopped pump treatment temporarily due to instable calcium concentrations.

In conclusion, we describe continuous subcutaneous PTH infusion as a suitable treatment for ADH that cannot be controlled conventionally. We also describe a new CaSR mutation resulting in ADH and cataract as a not previously described feature in ADH. Longer follow up is required to assess whether continuous sc PTH treatment delays the progression of nephrocalcinosis.

 

Nothing to Disclose: EFG, JB, NA, RVT, JA