Acute effects of calcitriol and phosphate salts on mineral metabolism in children with hypophosphatemic rickets.

Abstract

We investigated the acute effects of oral administration of 1,25-dihydroxyvitamin D (1,25-(OH)2D) and phosphate on the major mineral metabolism indexes in six children with vitamin D-resistant rickets treated with a long-term regimen of phosphate and calcitriol. Two acute tests were performed in which plasma calcium, phosphate, immunoreactive parathyroid hormone (iPTH) (intact molecule), 25-hydroxyvitamin D (25-OHD), and 1,25-(OH)2D levels were measured: the first after an oral phosphate load (20 mg/kg) was administered after calcitriol had been discontinued for 10 days, and the second after a calcitriol load (0.03 microgram/kg) plus the same phosphate load but with the children receiving the usual combination treatment. There were no significant differences in basal levels of calcium, phosphate, iPTH, 25-OHD, or 1,25-(OH)2D between the two tests, nor were delta percent calcium and 25-OHD values significantly different. The delta percent plasma phosphate concentration at 60 minutes was significantly higher during test 2 than during test 1 (p less than 0.01) and delta percent iPTH concentration at 60 minutes was significantly higher during test 1 than during test 2 (p less than 0.01). In test 2 the iPTH level returned to baseline at 180 minutes. Higher delta percent 1,25-(OH)2D values at 60 minutes were observed in test 2 than in test 1 (p less than 0.01). Furthermore, the delta percent 1,25-(OH)2D levels were still higher at 180 minutes in test 2 than during test 1 (p less than 0.01). Our study indicates that oral calcitriol has an inhibitory effect on iPTH secretion in the hours immediately after oral phosphate administration in children with vitamin D-resistant rickets.

• Authors: A Bettinelli, M L Bianchi, E Mazzucchi, G Gandolini, A C Appiani
• Journal: The Journal of pediatrics (J Pediatr) Vol. 118 Issue 3 Pg. 372-6 (Mar 1991) ISSN: 0022-3476 [Print] United States
• PMID: 1847972 (Publication Type: Journal Article)

Chemical References

• Blood Proteins
• Minerals
• Parathyroid Hormone
• Phosphates
• 25-Hydroxyvitamin D 2
• Creatinine
• Calcitriol
• Calcium

Topics

• 25-Hydroxyvitamin D 2 (blood)
• Administration, Oral
• Adolescent
• Blood Proteins (analysis)
• Calcitriol (administration & dosage, blood, pharmacology)
• Calcium (blood)
• Child
• Child, Preschool
• Creatinine (blood)
• Humans
• Hypophosphatemia, Familial (blood)
• Minerals (blood)
• Parathyroid Hormone (blood)
• Phosphates (administration & dosage, blood, pharmacology)