Hypovitaminosis D in a sunny country: Time trends, predictors, and implications for practice guidelines

The aim of the current study is to investigate the prevalence of hypovitaminosis D in Lebanese subjects, its robust predictors, evaluate the relationship between 25 hydroxy vitamin D [25(OH)D] and parathyroid hormone levels, and derive desirable vitamin D levels, based on a large hospital laboratory database spanning all age groups.Data from a large representative digitized database of 9147 subjects, mostly outpatients, evaluated between 2000–2004 and 2007–2008, in whom information on age, gender, service, and time of the year, was analyzed. The PTH–25(OH)D relationship was studied in a subset of 657 adult subjects, in whom such data were available.At a 25(OH)D cut-off of < 20 ng/ml, the prevalence of hypovitaminosis D ranged between 58% and 62% in pediatric subjects, 44% and 60% in adults, and 41% and 62% in elderly, in the 2 study periods. At a cut-off < 30 ng/ml, the prevalence was above 78%, in most sub-groups. Regardless of cut-off used, the only significant predictors of high mean 25(OH)D levels were the male gender in the pediatric group, and female gender in adults and elderly, summer/fall seasons, out-patient status, as well as study period. Curve fitting of the PTH–25(OH)D relationship, in adults and elderly, revealed a plateau at 25(OH)D levels of 17–21 ng/ml, depending on sub-study group.Hypovitaminosis D is prevalent in our sunny country, even using a conservative population-derived cut-off of 20 ng/ml, and thus the need for a public health strategy for supplementation.