Vitamin D Insufficiency in a Hospital Population: A Photograph from the Laboratory Perspective

Abstract

Introduction: Although vitamin D deficiency is increasingly recognized around the world, there are few studies on the Portuguese reality. This study aims to analyse vitamin D levels in the assays performed in our hospital and their relationship with age, genre, requesting specialty and moment of sample collection.
Material and Methods: Cross-sectional study of measurements of 25(HO)D performed in our Hospital between June 2012 and November 2014. Included variables: gender, age, requesting specialty, month of sample collection. Vitamin D status classified as: ‘Deficiency’ (≤ 20 ng/mL), ‘Insufficiency’ (21 - 29 ng/ml) and ‘Sufficiency’ (≥ 30 ng/mL).
Results: We included 5 439 assays; 55.0% from women; the median age was 64.0 years. Sixty per cent had ‘Deficiency’, 20.7% ‘Insufficiency’ and 18.9% ‘Sufficiency’. We found a negative correlation between age and vitamin D level (p < 0.001). We didn’t find differences in vitamin D levels between genres. Nine specialties requested 98% of the assays, namely Nephrology (56.2%). We found differences between specialties based on age and vitamin D level (p < 0.001). Vitamin D levels changed throughout the year, with higher levels in the summer, followed by autumn, spring and winter (p < 0.001). Despite this seasonal fluctuation, vitamin D sufficiency was only present in a minority of assays (27.8% in summer and 9.2% in winter).
Discussion: Vitamin D deficiency is prevalent in this population, affects individuals of all ages and is not offset by the seasonal variation of sunlight.
Conclusion: Vitamin D deficiency is a real and prevalent problem in our population that needs further attention and action, given its clinical implications.