K Kruse1. 1. Department of Pediatrics, Medical University of Luebeck, Germany.
Abstract
OBJECTIVE: To improve understanding of the biochemical events in vitamin D-deficiency rickets (VDR). METHODS: We investigated 51 untreated patients, 2 to 36 months of age, during three stages of VDR. Nineteen of these patients were also studied during therapy with 5000 to 10,000 U vitamin D3 (cholecalciferol) and 0.5 to 1 gm calcium. Together with calcium and inorganic phosphate in serum and urine, we measured (1) parathyroid hormone (PTH) secretion (intact serum PTH) and action on the kidney (urinary adenosine 3',5'-cyclic monophosphate (cAMP)/creatinine ratio; (2) serum alkaline phosphatase level; (3) urinary hydroxyproline/creatinine ratio; and (4) serum 1,25-dihydroxyvitamin D (1,25(OH)2D) level. RESULTS: The untreated patients had secondary hyperparathyroidism (high serum PTH and urinary cAMP/creatinine ratio), low calcium and phosphate concentrations in serum, and increased bone turnover (elevated serum alkaline phosphatase and OHP/creatinine ratio), whereas serum 1,25(OH)2D was low, normal, or even slightly elevated. Serum calcium level was positively correlated to serum 1,25(OH)2D and to OHP/creatinine ratio, indicating that normocalcemia in untreated rickets (stage 2) is at least partially maintained by 1,25(OH)2D-induced calcium mobilization from bone. There was no correlation between serum calcium and serum PTH, or between serum PTH and urinary cAMP/creatinine ratio or serum phosphate, indicating disturbed regulation and action of PTH. During vitamin D treatment, serum 1,25(OH)2D values increased to supranormal concentrations in association with the restoration of the physiologic relationship of PTH to serum calcium and phosphate concentrations and urinary cAMP/creatinine ratio. CONCLUSION: Circulating 1,25(OH)2D has an important role in the pathophysiology of VDR before and during treatment, mainly by influencing the bone and kidney response to endogenous PTH.
OBJECTIVE: To improve understanding of the biochemical events in vitamin D-deficiency rickets (VDR). METHODS: We investigated 51 untreated patients, 2 to 36 months of age, during three stages of VDR. Nineteen of these patients were also studied during therapy with 5000 to 10,000 U vitamin D3 (cholecalciferol) and 0.5 to 1 gm calcium. Together with calcium and inorganic phosphate in serum and urine, we measured (1) parathyroid hormone (PTH) secretion (intact serum PTH) and action on the kidney (urinary adenosine 3',5'-cyclic monophosphate (cAMP)/creatinine ratio; (2) serum alkaline phosphatase level; (3) urinary hydroxyproline/creatinine ratio; and (4) serum 1,25-dihydroxyvitamin D (1,25(OH)2D) level. RESULTS: The untreated patients had secondary hyperparathyroidism (high serum PTH and urinary cAMP/creatinine ratio), low calcium and phosphate concentrations in serum, and increased bone turnover (elevated serum alkaline phosphatase and OHP/creatinine ratio), whereas serum 1,25(OH)2D was low, normal, or even slightly elevated. Serum calcium level was positively correlated to serum 1,25(OH)2D and to OHP/creatinine ratio, indicating that normocalcemia in untreated rickets (stage 2) is at least partially maintained by 1,25(OH)2D-induced calcium mobilization from bone. There was no correlation between serum calcium and serum PTH, or between serum PTH and urinary cAMP/creatinine ratio or serum phosphate, indicating disturbed regulation and action of PTH. During vitamin D treatment, serum 1,25(OH)2D values increased to supranormal concentrations in association with the restoration of the physiologic relationship of PTH to serum calcium and phosphate concentrations and urinary cAMP/creatinine ratio. CONCLUSION: Circulating 1,25(OH)2D has an important role in the pathophysiology of VDR before and during treatment, mainly by influencing the bone and kidney response to endogenous PTH.
Authors: Craig F Munns; Nick Shaw; Mairead Kiely; Bonny L Specker; Tom D Thacher; Keiichi Ozono; Toshimi Michigami; Dov Tiosano; M Zulf Mughal; Outi Mäkitie; Lorna Ramos-Abad; Leanne Ward; Linda A DiMeglio; Navoda Atapattu; Hamilton Cassinelli; Christian Braegger; John M Pettifor; Anju Seth; Hafsatu Wasagu Idris; Vijayalakshmi Bhatia; Junfen Fu; Gail Goldberg; Lars Sävendahl; Rajesh Khadgawat; Pawel Pludowski; Jane Maddock; Elina Hyppönen; Abiola Oduwole; Emma Frew; Magda Aguiar; Ted Tulchinsky; Gary Butler; Wolfgang Högler Journal: J Clin Endocrinol Metab Date: 2016-01-08 Impact factor: 5.958