Abstract
The circulating plasma 25-hydroxyvitamin D (25-OHD) levels have been measured in 4078 Saudi subjects. The frequencies of insufficient (below 5 ng/ml) and low (5-10 ng/ml) plasma concentrations of 25-OHD have been reported. The frequency of low 25-OHD (5-10 ng/ml) is high for children (21.9%) and for adults (20.4%), whereas the frequency of 25-OHD insufficiency (<5 ng/ml) in these two groups is 3.4% and 5.5% respectively. These proportions were unaffected by whether the populations were from an urban or rural background. The frequency of low 25-OHD levels was higher in females than in males at any given age. The most affected females were adolescents and adults. It was observed that, in males the frequency of 25-OHD insufficiency (i.e. <5 ng/ml) increased with age.