medwireNews: Using an insulin pump to provide subcutaneous parathyroid hormone (PTH) is an option for children with hypoparathyroidism and intestinal malabsorption, report researchers.
As described in Hormone Research in Paediatrics, Vrinda Saraff and colleagues tested the approach in four children with hypoparathyroidism who received routine treatment with alfacalcidol and oral calcium but had persistent hypocalcaemia because of poor intestinal absorption. Increasing the oral calcium dose in two cases resulted in hypercalciuria and worsening diarrhoea.
This led the researchers from Birmingham Children’s Hospital in the UK and Bicêtre Hospital in Paris, France, to try continuous subcutaneous recombinant parathyroid hormone 1–34 infusion (CSPI), which has previously been reported in children with mutations in the calcium-sensing receptor and with autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED).
The patients, who were all boys, were diagnosed between the ages of 8 months and 11 years and were aged between 13 and 19 years at the time of the report. Three had APECED and one had congenital hypoparathyroidism with sensory-neural deafness, intestinal lymphangiectasia and cryptogenic liver disease.
The first two patients to start CSPI did so at a dose of 2.6 μg/kg per day, reduced to 0.5 μg/kg per day (in one patient; the other died of acute adrenal insufficiency during septic shock related to a dental abscess). The other two started on lower doses of 0.16 and 1.0 μg/kg per day, and ended up on maintenance doses of around 0.3 μg/kg per day.
In all cases, serum calcium normalised within 2 days, alfacalcidol was stopped, and just one patient continued to require oral calcium, albeit at a reduced dose. The patients have so far remained on CSPI for between 3 and 8 years. Any episodes of hypocalcaemia during this time were associated with mechanical obstruction of PTH delivery, insufficient vitamin D or oral calcium supplementation, systemic illness and puberty growth spurt – there was most usually a combination of these factors.
There was a “substantial” reduction in hypocalcaemia-related hospitalisations, and all patients felt that CSPI had improved their quality of life.
“In the absence of other new treatment options on the horizon in children, we propose CSPI as a promising and effective treatment method for children with hypoparathyroidism associated with intestinal malabsorption”, say the researchers, although they note that the markedly increased costs make it suitable only for children whose condition cannot be managed with conventional therapy.
They advise regular monitoring of serum calcium, especially soon after CSPI initiation, as well as periodic renal ultrasound and bone mineral density scans. Bone mineral density in the children in this study was initially higher than normal for their age. It reduced during CSPI but not to abnormally low levels, and no child had a fracture.
Horm Res Paediatr 2018; Advance online publication
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