Teriparatide (rhPTH) treatment in children with syndromic hypoparathyroidism

Abstract

BACKGROUND: Subcutaneous recombinant human parathormone [rhPTH (1-34)] has been introduced for hypoparathyroidism treatment, allowing avoidance of vitamin D and calcium side effects. OBJECTIVE: Our objective was to evaluate rhPTH (1-34) safety and efficacy in pediatric patients with genetically proved syndromic hypoparathyroidism. METHODS: The study was a 2.5-year self-controlled trial on six pediatric patients (four males, two females, age 9.8±5.1 years) with syndromic hypoparathyroidism including three with autoimmune polyendocrinopathy candidiasis ectodermal dysplasia (APECED) syndrome, two with DiGeorge syndrome, and one with hypoparathyroidism-deafness-renal dysplasia syndrome. We compared patients' clinical and biochemical outcome of conventional treatment based on oral administration of calcium (1-1.5 g/day in three doses) plus oral calcitriol (6.5-33 ng/kg per day in two to three doses) with the outcome obtained with rhPTH (1-34) (teriparatide, 12.5 μg bid). Therapy shift was conducted introducing rhPTH (1-34) while progressively withdrawing calcium and vitamin D. Blood calcium, phosphorus, alkaline phosphatase, and urinary calcium-to-creatinine ratio (mg/mg) before and during rhPTH therapy were compared. RESULTS: rhPTH treatment allowed complete calcium and vitamin D withdrawal in two patients, calcium withdrawal in three and reduction of vitamin D dose in two. During rhPTH (1-34), mean blood calcium, phosphorus, and alkaline phosphatase were not significantly modified, whereas significant reduction of the calciuria-to-creatininuria ratio (0.55±0.31 vs. 0.1±0.1, p=0.02) was obtained. The number of tetanic episodes was reduced in four patients during teriparatide treatment compared to conventional treatment. CONCLUSION: In children with syndromic hypoparathyroidism, substitutive treatment with rhPTH (1-34) maintains adequate blood calcium levels and allows prompt normalization of urinary calcium excretion, through direct action on the kidney and through calcium and vitamin D therapy layoff.