The Journal of Steroid Biochemistry and Molecular Biology
Twice single doses of 100,000 IU of vitamin D in winter is adequate and safe for prevention of vitamin D deficiency in healthy children from Ushuaia, Tierra Del Fuego, Argentina
Introduction
The production of endogenous vitamin D is affected by the geographic latitude of residence, the degree of skin pigmentation, the season of the year, clothing, atmospheric pollution and the application of sunscreen [1], [2]. Geographic latitude of residence and skin pigmentation are the dominants factors [3]. People who live in higher latitudes are vulnerable to seasonal hypovitaminosis during winter because of inadequate sunlight exposure [4]. Vitamin D deficiency causes rickets in children, and during childhood and adolescence, vitamin D is an important factor for optimizing the peak of bone mass [5]. In Argentina, that extends between latitudes 22–55°S (the Antarctic region extends to latitude 78°S), vitamin D deficiency has been reported in children [6], [7], [8]. In Ushuaia, latitude 55°S, a single vitamin D supplementation has been tried at the beginning of winter in healthy children, improving this vitamin D deficiency [9]. However, pediatricians of this region still reported rickets. In order to improve the vitamin D status of children from Ushuaia, a double supplementation [10] with 100,000 IU of vitamin D was administered to healthy children at the beginning and during winter.
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Subjects and methods
After informed consent by parents, 18 healthy children were studied in Ushuaia, 55°S, seven girls and 11 boys, age (mean ± S.D.): 7.3 ± 4.4 years old. A questionnaire was made in reference to calcium intake by dairy products and previous vitamin D intake. Weight, height, economic and social status, and type of skin of each child were considered. Children with bone, hepatic, renal or skin disease, and those with height or weight less or more than Z-score −2 or +2, were excluded of the study. Two
Results
Calcium intake was of 770 ± 420 mg/day.
Height and weight of children were in Z-score: –0.04 ± 0.77 and 0.25 ± 1.79, respectively. Twenty five-hydroxyvitamin D was in the normal range in every child. It increased in April (from 29.3 ± 5.9 to 35.3 ± 4.4 ng/ml, p < 0.001) and decreased in September (22.4 ± 4.6 ng/ml, p < 0.001, Fig. 1 and Table 1). None has deficiency any insufficiency of vitamin D.
There was a negative relationship between levels of 25OHD and the age of children (r: −0.48, p < 0.04). There was no
Discussion
Serum concentration of 25OHD is an accepted index of vitamin D nutritional status because it is directly related to exposure to sunshine and to the oral intake of vitamin D [13]. Low levels of 25OHD, on the basis of substrate deficiency, may limit the 1,25-hydroxyvitamin D production, the hormonal metabolite that maintains the calcium and phosphate homeostasis [14]. Severe vitamin D deficiency results in osteomalacia in adults and rickets in children.
At higher latitudes, where there is only
Acknowledgement
The vitamin D was provided by Spedrog-Caillon laboratories.
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- 1
Present address: 1° de Mayo 5565, 1824 Lanus Oeste, Buenos Aires, Argentina.
- 2
Present address: Pediatría, Hospital Regional de Ushuaia, 12 de Octubre y Maipú, CP. 9410, Ushuaia, Tierra del Fuego, Argentina.
- 3
Present address: Laboratorio, Hospital Regional de Ushuaia, 12 de Octubre y Maipú, CP. 9410, Ushuaia, Tierra del Fuego, Argentina.