Objective: To study the prevalence of hypovitaminosis D [serum 25(OH)D < or = 37 nmol L-1)] in Finnish medical in- and outpatients in a cross-sectional study.
Methods: The subjects were 106 consecutive medical inpatients (57 females, 49 males with mean ages of 65 and 58 years) from the Peijas Hospital, Vantaa, Finland, and 99 ambulatory patients (48 females, 51 males with mean ages of 42 and 46 years) contacting a private outpatient centre in Helsinki, Finland. Serum 25(OH)D, vitamin D binding protein (DBP), free vitamin D index (FDI), intact PTH (iPTH), and albumin-corrected calcium were measured.
Results: Serum 25-hydroxyvitamin D [25(OH)D] was 37 nmol L(-1) or less in 70% of female and in 61% of male inpatients and in 44% of female and in 37% of male outpatients. In the whole population, a statistically significant inverse association (P < 0.0001) was detected between iPTH and 25(OH)D levels; the iPTH concentration appeared to start increasing when 25(OH)D concentration was 50 nmol L(-1) or less. The association remained the same (P < 0.0001) when FDI was used instead of 25(OH)D in the calculations. When the sexes were analysed separately, the statistically significant association was found only in females (P < 0.0001 for iPTH versus 25(OH)D; P < 0.0001 for iPTH versus FDI) but not in males.
Conclusion: Hypovitaminosis D is very common amongst Finnish in- and outpatients in both sexes, causing secondary hyperparathyroidism in females. More extensive studies are warranted to elucidate the vitamin D status of the Finnish population.