ASSOCIATION BETWEEN 25-HYDROXYVITAMIN D AND INTACT PARATHYROID HORMONE LEVELS ACROSS LATITUDE AMONG ADULTS WITH AFRICAN ANCESTRY. Journal Article

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Authors: Kramer, H; Camacho, P; Aloia, J; Luke, A; Bovet, P; Rhule, JP; Forrester, T; Lambert, V; Harders, R; Dugas, L; Cooper, R; Durazo-Arvizu, R
Article Title: ASSOCIATION BETWEEN 25-HYDROXYVITAMIN D AND INTACT PARATHYROID HORMONE LEVELS ACROSS LATITUDE AMONG ADULTS WITH AFRICAN ANCESTRY.
Abstract: OBJECTIVE: To compare levels of 25-hydroxyvitamin D (25[OH]D) associated with a plateauing of intact parathyroid (iPTH) across latitudes among adults with African ancestry. METHODS: This study included approximately 500 adults of African ancestry ages 25 to 45 years living in 4 sites: Chicago, Illinois (41°N), Jamaica (17°N), Ghana (6°N), and South Africa (34°S). Multivariate linear regression models, a nonlinear logistic growth curve model, and piecewise linear models with a single knot were fitted to estimate the 25[OH]D level associated with a plateauing of iPTH with adjustment for covariates. Goodness of fit was compared using computer intensive permutation tests. RESULTS: Mean age was 34.7 (SD 6.2) years, and 46.5% were male. Within each site, the percentage of participants with an iPTH level =65 pg/mL was higher among females versus males and was most frequent among South African females (17.1%) and lowest among Jamaican males (0.6%). Goodness of fit tests supported linear regression as the preferred model for the association between iPTH and 25[OH]D in the 4 sites with no 25[OH]D level associated with iPTH plateauing in any site. The slope of the association between 25[OH]D and iPTH differed by latitude; it was strongest in the U.S. (ß = -0.81; 95% confidence interval [CI] = -1.03, -0.59), and weakest in Jamaica (ß = -0.45; 95% CI -0.71, -0.18) with covariate adjustment, but differences in slopes were small. CONCLUSION: The association between 25[OH]D and iPTH appears linear among adults with African ancestry regardless of latitude within a range of 25[OH]D levels between 10 and 60 ng/mL. ABBREVIATIONS: BMI = body mass index CI = confidence interval eGFR = estimated glomerular filtration rate iPTH = intact parathryoid hormone 25[OH]D = 25-hydroxyvitamin D.
Journal Title: Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists
ISSN: 1934-2403; 1530-891X
Publisher: Unknown  
Date Published: 2016