Paradoxical Response of Parathyroid Hormone to Vitamin D-Calcium Supplementation in Indian Children.

OBJECTIVES: To investigate the effect of oral vitamin D-calcium supplementation on serum intact parathyroid hormone (PTH), calcium, phosphorous, and alkaline phosphatase (ALK-P) concentrations in children with habitually low calcium intakes. STUDY DESIGN: In this follow-up study to a randomized controlled trial that aimed to assess the effect of vitamin D-calcium supplementation on immunity, data related to dietary intake, anthropometry, and biochemistry [serum 25(OH)D and bone profile] were collected from 178 children-79 in the vitamin D group and 99 in the non-vitamin D group. RESULTS: Dietary calcium to phosphorus intake ratio was 0.4:1. Baseline serum 25(OH)D concentration was 58.2 ± 10.9 nmol/L; 66% children were vitamin D sufficient and none deficient. After supplementation, vitamin D group, compared with the non-vitamin D group, had significantly (P < .05) greater 25(OH)D (83.9 ± 30.1 nmol/L vs 58.3 ± 15.7 nmol/L), significantly greater PTH (6.7 ± 3.6 pmol/L vs 5.5 ± 3.2 pmol/L), and positive correlation (rs = 0.24) between serum 25(OH)D and PTH (vs negative correlation [rs = -0.1] in non-vitamin D group). Mean concentrations of serum bone measures in the vitamin D group were calcium (2.2 ± 0.1 mmol/L), phosphorus (1.7 ± 0.2 mmol/L), and ALK-P (178.7 ± 40.7 IU/L). At follow-up, 1-year post-supplementation, in the vitamin D group, PTH concentrations continued to remain high (but not significantly different from levels at 6 months), with low normal serum calcium, high normal phosphate, and ALK-P in reference range. CONCLUSIONS: In children who are vitamin D sufficient but with habitually low dietary calcium intake, vitamin D-calcium supplementation paradoxically and significantly increased serum PTH concentrations with no apparent effect on other bone biochemistry. Chronic low dietary calcium to phosphorus ratio is likely to have caused this paradoxical response.

Changes in body composition of Indian lactating women: a longitudinal study.

BACKGROUND AND OBJECTIVES: Lactation places enormous demands on maternal bone mineral homeostasis. Indian middle class women (MSC) consume energy dense food supplements to meet these demands post-partum (PP) along with restricted physical activity (PA). Effects of these changes on body composition (BC) of PP women have not been studied. To examine longitudinal changes in: a) bone mineral density (BMD) at total body (TB), AP-spine (APS) and dual femur neck regions (DF) b) BC by body weight, lean mass, fat mass using dual energy X-ray absorptiometry (DXA) at baseline, 6-months and 1-year in urban MSC women. METHODS AND STUDY DESIGN: 76-primi-parous (28±3.2 yrs) randomly selected PP women (<7-days) were studied; 70 reassessed at 6- months and 42 1-yr PP. Data on anthropometry, BC, BMD at TB, APS and DF by DXA collected (baseline, 6- months, 1-yr PP). RESULTS: Weight, waist and body mass index (BMI) decreased both at 6-month and 1-yr PP with respect to baseline (p<0.05). BC changes showed increase in android fat % at 1-yr by 10% over baseline (p<0.05). BMD with initial decline at 6-months (-2.8%, -2.3% and -2.3% respectively) recovered partially by 1-yr (+2.5% +1.2% and +4.8% respectively) at DF and TB with complete recovery at APS (p<0.05). CONCLUSION: These urban relatively sedentary MSC women consumed fat rich food PP with higher android fat retention and partial recovery of BMD at DF and TB at 1-year. Modifications in activity and dietary nutrient intakes may be necessary to prevent cardiovascular and bone health related risks.