Vitamin D status and its association with parathyroid hormone concentrations in women of child-bearing age living in Jakarta and Kuala Lumpur

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Abstract
Objective: To describe the vitamin D status of women living in two Asian cities, – Jakarta (6°S) and Kuala-Lumpur (2°N), to examine the association between plasma 25-hydroxyvitamin D and parathyroid hormone (PTH) concentrations, and to determine a threshold for plasma 25-hydroxyvitamin D above which there is no further suppression of PTH. Also, to determine whether dietary calcium intake influences the relationship between PTH and 25-hydroxyvitamin D. Design: Cross-sectional. Setting: Jakarta, Indonesia and Kuala Lumpur, Malaysia. Participants: A convenience sample of 504 non-pregnant women 18–40 years. Main measures: Plasma 25-hydroxyvitamin D and PTH. Results: The mean 25-hydroxyvitamin D concentration was 48 nmol/l. Less than 1% of women had a 25-hydroxyvitamin D concentration indicative of vitamin D deficiency (P=0.003) and −0.01 (P=0.775), respectively. The relation between vitamin D status and parathyroid hormone concentration did not differ between women with low, medium or high calcium intakes (P=0.611); however, even in the highest tertile of calcium intake, mean calcium intake was only 657 mg/d. Conclusion: On the basis of maximal suppression of PTH we estimate an optimal 25-hydroxyvitamin D concentration of ∼ 50 nmol/l. Many women had a 25-hydroxyvitamin D below this concentration and may benefit from improved vitamin D status.