VITAMIN-D DEFICIENCY IN HOMEBOUND ELDERLY PERSONS

Objective.-To assess the vitamin D status in homebound, community-dwel ling elderly persons; sunlight-deprived elderly nursing home residents ; and healthy, ambulatory elderly persons. Design.-A cohort analytic s tudy. Participants.-Of 244 subjects at least 65 years old, 116 subject s (85 women and 31 men) had been confined indoors for at least 6 month s, either in private dwellings in the community (the Hopkins Elder Hou secall Program) or in a teaching nursing home (The Johns Hopkins Geria trics Center). The 128 control subjects, a healthy ambulatory group, c ame from the Baltimore Longitudinal Study on Aging. All subjects were free of diseases or medications that might interfere with their vitami n D status. Main Outcome measures.-Serum levels of 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D (1,25-[OH]D-2) were measured in all subjects. In a subgroup of 80 subjects, serum levels of intact par athyroid hormone (PTH), ionized calcium, and osteocalcin and intake of vitamin D (through 3-day food records) were assessed. A randomly sele cted cohort of sunlight-deprived subjects also had serum levels of vit amin D binding protein measured. Results.-In sunlight-deprived subject s overall, the mean 25-OHD level was 30 nmol/L (12 ng/mL) (range, <10 to 77 nmol/L [<4 to 31 ng/mL]) and the mean 1,25(OH)(2)D level was 52 pmol/L (20 pg/mL) (range, 18 to 122 pmol/L [7 to 47 pg/mL]). In the su nlight-deprived subjects, 54% of community dwellers and 38% of nursing home residents had serum levels of 25-OHD below 25 nmol/L (10 ng/mL) (normal range, 25 to 137 nmol/L [10 to 55 ng/mL]). A significant inver se relationship existed between 25-OHD (ie, Log [25-OHD]) and PTH when they were analyzed together (r=-0.42; R(2)=0.18; P<.001) and for each cohort separately. All other parameters measured, except ionized calc ium, differed significantly from the Baltimore Longitudinal Study Grou p means. The mean (SD) daily intakes of vitamin D (121 [132] IU) and c alcium (583 [322] mg) were below the recommended dietary allowance onl y in the community-dwelling homebound population. The mean vitamin D b inding protein level in the sunlight-deprived subgroup was in the norm al range. Conclusions.-Despite a relatively high degree of vitamin sup plementation in the United States, homebound elderly persons are likel y to suffer from vitamin D deficiency.