Determinants of parathyroid hormone response to vitamin D supplementation: a systematic review and meta-analysis of randomised controlled trials.
This systematic review aimed to assess the determinants of the parathyroid hormone (PTH) level response to vitamin D supplementation. We searched Medline, Google Scholar and the reference lists of previous reviews. All randomised controlled trials (RCT) on vitamin D supplementation that involved apparently healthy human subjects with a report of PTH were selected. Potential studies were screened independently and in duplicate. Results are summarised as mean differences with 95% confidence intervals. Quality assessment, subgroup analysis, meta-analysis and meta-regression analysis were carried out. Thirty-three vitamin D supplementation RCT were included. Vitamin D supplementation significantly raised circulating 25-hydroxyvitamin D (25(OH)D) with significant heterogeneity among studies with a pooled mean difference (PMD) of 15.5 ng/ml (test for heterogeneity: P<0·001 and I 2=97·3%). Vitamin D supplementation significantly reduced PTH level with PMD of -8·0 pg/ml, with significant heterogeneity ((test for heterogeneity: P<0·001) and the I 2 value was 97·3%). In the subgroup analyses, the optimum treatment effect for PTH was observed with Ca doses of 600-1200 mg/d (-22·48 pg/ml), after the duration of a >12-month trial (-18·36 pg/ml), with low baseline 25(OH)D concentration of <20 ng/ml (-16·70 pg/ml) and in those who were overweight and obese (-18·11 pg/ml). Despite the present meta-analysis being hindered by some limitations, it provided some interesting evidence, suggesting that suppression of PTH level needs higher vitamin D intake (75 μg/d) than the current recommendations and longer durations (12 months), which should be taken into account for nutritional recommendations.
1Nutrition and Endocrine Research Center,Research Institute for Endocrine Sciences,Shahid Beheshti University of Medical Sciences,9395-4763 Tehran,Iran.
Nazanin
N
Moslehi
2Department of Community Nutrition,School of Nutritional Sciences and Dietetics,Tehran University of Medical Sciences,14155-6117 Tehran,Iran.
Sakineh
S
Shab-Bidar
3Department of Clinical Nutrition and Dietetics, Faculty of Nutrition Sciences and Food Technology,National Nutrition and Food Technology Research Institute,Shahid Beheshti University of Medical Sciences,19395-4741 Tehran,Iran.
Parvin
P
Mirmiran
4Obesity Research Center,Research Institute for Endocrine Sciences,Shahid Beheshti University of Medical Sciences,19395-4763 Tehran,Iran.
Farhad
F
Hosseinpanah
5Endocrine Research Center,Research Institute for Endocrine Sciences,Shahid Beheshti University of Medical Sciences,19395-4763 Tehran,Iran.
Fereidoun
F
Azizi
D019587:Dietary Supplements; D006801:Humans; D009765:Obesity / Q000097:blood / Q000188:drug therapy; D050177:Overweight / Q000097:blood / Q000188:drug therapy; D010281:Parathyroid Hormone / Q000097:blood*; D016032:Randomized Controlled Trials as Topic; D014807:Vitamin D / Q000008:administration & dosage*
D010281:Parathyroid Hormone; D014807:Vitamin D
25(OH)D 25-hydroxyvitamin D; Cholecalciferol; MD mean difference; Meta-analyses; PMD pooled mean difference; PTH parathyroid hormone; Parathyroid hormone; RCT randomised controlled trial; Randomised controlled trials; Vitamin D