Vitamin D prophylaxis in children with a single dose of 150000 IU of vitamin D.

OBJECTIVE: To determine the efficacy of a single oral dose of 150,000 IU of vitamin D2 at the beginning of autumn for preventing winter vitamin D deficiency in children in Ushuaia (55 degrees S). DESIGN: The study was prospective. SUBJECTS: 79 children clinically healthy with 8.6 +/- 1.4 y of age (X +/- s.d.). INTERVENTIONS: Fasting serum venous samples and 2 h urine samples were obtained immediately before and 6 w and 5 mon after the vitamin D dose. Parents informed consent was obtained previous to the study. In a subgroup of 30 children serum levels of calcium (sCa), phosphorus (sP), total alkaline phosphatase (TAP), 25 hydroxyvitamin D (25 OHD), parathyroid hormone (PTH) and the urine calcium/creatinine ratio in a 2 h urine sample (UCa/UCreat) were measured. In the whole group sCa and the ratio uCa/ucreat were measured. RESULTS: After 150,000 IU of vitamin D2 administration, serum 25 OHD levels at the end of winter (17.0 +/- 9.4 ng/ml) were similar to those at the beginning of autumn (18.7 +/- 10.7 ng/ml), but significantly higher from those obtained in a previous study without vitamin D (9.8 +/- 3.8 ng/ml, P < 0.001). PTH levels were higher at the end of winter (P < 0.02), but this augmentation was lower than the increment observed without vitamin D. Plasma calcium levels and the urine calcium/creatinine ratio were lower at 5 months after vitamin D2 dose (P < 0.02 and P < 0.05 respectively). In the total group the serum calcium was lower after the fifth month (P < 0.05). The Uca/Ucreat ratio was lower at 6 w and 5 mon (P < 0.05 and P < 0.001). CONCLUSION: A single dose of 150,000 IU of vitamin D maintained appropriate levels of 25 OHD without inducing hypercalcemia nor hypercalciuria, but a winter increment of PTH (smaller than in the group without vitamin D) was not inhibited.