PREVALENCE OF VITAMIN-D INSUFFICIENCY IN AN ADULT NORMAL POPULATION

The vitamin D status of a general adult urban population was estimated between November and April in 1569 subjects selected from 20 French c ities grouped in nine geographical regions (between latitude 43 degree s and 51 degrees N). Major differences in 25-hydroxyvitamin D (25(OH)D ) concentration were found between regions, the lowest values being se en in the North and the greatest in the South, with a significant 'sun ' effect (r = 0.72; p = 0.03) and latitude effect (r = -0.79; p = 0.01 ). In this healthy adult population, 14% of subjects exhibited 25(OH)D values less than or equal to 30 nmol/l (12 ng/ml), which represents t he lower limit (< 2 SD) for a normal adult population measured in wint er with the same method (RIA Incstar). A significant negative correlat ion was found between serum intact parathyroid hormone (iPTH) and seru m 25(OH)D values (p < 0.01), Serum iPTH held a stable plateau level at 36 pg/ml as long as serum 25(OH)D values were higher than 78 nmol/l ( 31 ng/ml), but increased when the serum 25(OH)D value fell below this, When the 25(OH)D concentration became equal to or lower than 11.3 nmo l/l (4.6 ng/ml), the PTH values reached the upper limit of normal valu es (55 pg/ml) found in vitamin D replete subjects. These results showe d that in French normal adults living in an urban environment with a l ack of direct exposure to sunshine, diet failed to provide an adequate amount of vitamin D. It is important to pay attention to this rather high prevalence of vitamin D insufficiency in the general adult popula tion and to discuss the clinical utility of winter supplementation wit h low doses of vitamin D.