Need 40 ng of vitamin D to have proper PTH levels – May 2011

Defining Vitamin D Status by Secondary Hyperparathyroidism in the U.S. Population.

J Endocrinol Invest. 2011 May 23.
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.

PMID: 21606669

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