Time Trends and Predictors of Hypovitaminosis D Across the Life Course: 2009–2016
Randa K. Saada Metabol. 2020.
Highlights
•There was a significant steady increase in mean serum 25OHD levels from 2009 to 2016
•The average prevalence of low 25OHD (< 20 ng/ml) was 39% across all years
•Young age, male sex, winter and hospitalization predict low 25OHD in adults/elderly
•Older age, female sex, winter and hospitalization predict low 25OHD in children
•In adults and elderly, PTH levels plateaued at a serum 25OHD level of 23.4 ng/ml
Purpose
We investigated prevalence, determinants, seasonal changes, and time trends in hypovitaminosis D. We derived a desirable serum 25-hydroxy-vitamin D (25OHD) level in adults/elderly by evaluating the 25OHD-parathyroid hormone (PTH) exponential relationship.
Methods
We analyzed serum 25OHD data from a large laboratory database (N = 151,394), from a major academic medical center in Lebanon, from 2009 to 2016. We used cross calibration formulas to convert measured 25OHD levels to LC-MS/MS equivalents based on our external quality assurance protocols.
Results
6% of the population were children (mean age 11 ± 5 years, 57% girls), 69% were adults (44 ± 13 years, 71% women), and 25% were elderly (74 ± 6 years, 58% women). The prevalence of hypovitaminosis D, in the entire population, was 39%, 28% and 22% at 25OHD cutoffs of 20 ng/ml, 15 ng/ml, and 12 ng/ml, respectively, across all years. Using multivariate analysis, predictors of 25OHD levels below 12, 15 and 20 ng/ml were younger age, male sex, winter months, and inpatient status both in adults and elderly. In children, older age, female sex, winter months, and inpatient status, predicted levels below 15 ng/ml, but only older age, female sex, and winter months predicted levels below 12 ng/ml and 20 ng/ml. There was a significant steady annual increase in 25OHD levels between 2009 and 2016 of 0.8 ng/ml/year (95% CI: 0.7, 1.0) in children, 1.2 ng/ml/year (1.2, 1.3) in adults and 2.6 ng/ml/year (2.6, 2. in the elderly. Using best fit non-linear regression models, on a subset of adults and elderly in whom concomitant 25OHD and PTH data was available (N = 5885), PTH levels plateaued at a serum 25OHD level of 23.4 ng/ml.
Conclusion
Secular increase in serum 25OHD levels is observed in Lebanon, but hypovitaminosis D is still prevalent. Our data provides basis for a desirable 25OHD level above 23.4 ng/ml in adult and elderly Lebanese individuals.