SERUM CALCIDIOL AND CALCITRIOL CONCENTRATIONS IN ELDERLY PEOPLE - VARIATIONS WITH AGE, SEX, SEASON AND DISEASE

The influence of age, sex, seasonal variations and vitamin D supplemen tation on serum concentrations (s-conc.) of calcidiol and calcitriol w ere studied in 311 hospitalized and 106 home-living people aged 70 yea rs and over, residing at 60 degrees latitude. The serum calcidiol cone . (mean + SD, nmol/L) was reduced in the hospital group compared to th e home-living group (males: 40.6 +/- 23.2 compared to 59.6 +/- 28.9; f emales: 37.3 +/- 22.6 compared to 48.5 +/- 20.3) and showed no seasona l variation. The home-living group showed highest levels in August-Sep tember (62.2 +/- 26), and lowest levels in January-March (42.9 +/- 21) . Serum calcidiol declined with age, most prominent in the home group (males: r = -0.13, P = 0.036; females: r= -0.33, P = 0.001). A positiv e correlation was shown between s-calcitriol and s-calcidiol conc. (r= 0.26, P > 0.001). An increased s-conc. of calcidol was present in tho se with vitamin supplementation (home: 59.9 +/- 26; hospital: 43.4 +/- 22) compared to those without supplementation (home: 46.6 +/- 22; hos pital: 36.2 +/- 22), but s-calcidiol cone. did not correlate to nutrit ional vitamin D intake. Vitamin D deficiency (s-calcidiol cone. < 30 n mol/L) was more common in old people recently admitted to hospital, co mpared to those living at home. Only the home-living group had the ben efit of sunlight exposure, but both groups may benefit from vitamin su pplementation.