Defining Vitamin D Status by Secondary Hyperparathyroidism in the U.S. Population.
J Endocrinol Invest. 2011 May 23. https://doi.org/10.3275/7742
Ginde AA, Wolfe P, Camargo CA Jr, Schwartz RS.
From the Department of Emergency Medicine, University of Colorado Denver School of Medicine, Aurora, CO USA (AAG); Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora, CO USA (PW); Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA USA (CAC); Division of Geriatric Medicine, University of Colorado Denver School of Medicine, Aurora, CO USA (RSS).
PDF is available free at Sci-Hub 10.3275/7742
Background: Vitamin D is associated with a variety of health outcomes, but the exact definition of vitamin D sufficiency remains controversial.
Aim: We sought to define skeletal-related vitamin D sufficiency by estimating maximum parathyroid hormone (PTH) suppression in the U.S. population.
Methods: We performed a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES), 2003-2006. We examined the association between serum 25- hydroxyvitamin D (25OHD) level and serum PTH level in 14,681 participants aged?6 years. We also evaluated the 25OHD-PTH association using two thresholds of hyperparathyroidism- PTH?45 pg/ml and ?75 pg/ml.
Results: The mean 25OHD level was 24 ng/ml and mean PTH was 42 pg/ml. PTH?45 pg/ml was present in 35% of the population, while PTH?75 pg/ml) was present in 7%.
The prevalence of 25OHD levels <40 ng/ml and <30 ng/ml was 95% and 77%, respectively.
In both unadjusted and adjusted models, there was a strong inverse relationship between 25OHD and PTH. Compared to 25OHD?40 ng/ml, the 25OHD-PTH association was 2.36 (95%CI, 2.08-2.67) times greater for 25OHD<5 ng/ml and 1.12 (95%CI, 1.07-1.17) times greater for 25OHD 30- 39.9 ng/ml. Compared to 25OHD?40 ng/ml, 25OHD levels of 20-29.9 ng/ml (OR 2.0 [95%CI, 1.4-2.8]) but not 30-39.9 ng/ml (OR 1.1 [95%CI, 0.8-1.6]) were independently associated with PTH?45 pg/ml.
Conclusions: Optimal vitamin D status, defined by estimated maximum PTH suppression, does not occur until at least 25OHD levels ?40 ng/ml. Using these thresholds, most of the U.S. population needs more vitamin D. Large, prospective studies are needed to determine optimal vitamin D supplementation.