Hypovitaminosis D in an Italian population of healthy subjects and hospitalized patients

The present study aimed to investigate the prevalence and seasonal variatio n of hypovitaminosis D (defined as serum 25-hydroxyvitamin D level below 30 nmol/l) among healthy subjects and hospitalized patients living in central Italy. We studied 297 subjects, 131 in February 1997 and 166 in July 1997, subdivided into four groups: (a) young healthy blood donors; (b) healthy p ostmenopausal women; (c) inpatients with various medical diseases and (d) i npatients engaged in long-term rehabilitation programmes because of various neurological disorders. In all subjects and patients serum levels of 25-hy droxyvitamin D were measured by radioimmunoassay. We found a significant se asonal variation (P < 0.0001) of serum 25-hydroxyvitamin D levels, mean val ues being higher in summer in all groups, except in patients with a longer hospitalization time (group (d)). In each group, a significantly higher pre valence of hypovitaminosis D was found in winter compared with summer time (P < 0.001), being unexpectedly high in postmenopausal women (winter 32% an d summer 4.5%); furthermore, in both seasons, inpatients were characterized by the highest incidences of hypovitaminosis, particularly those in group (d) (winter 82.3 % and summer 57.8 %). The results of the present study emp hasize the importance of 25-hydroxyvitamin D measurement, and the need to i ncrease vitamin D intake in Italy; foodstuff fortification and supplement u se must be considered in order to prevent negative effects of vitamin D def iciency on Skeletal integrity.