Vitamin D deficiency in homebound elderly persons.
OBJECTIVE
To assess the vitamin D status in homebound, community-dwelling elderly persons; sunlight-deprived elderly nursing home residents; and healthy, ambulatory elderly persons.


METHODS
A cohort analytic study.


METHODS
Of 244 subjects at least 65 years old, 116 subjects (85 women and 31 men) had been confined indoors for at least 6 months, either in private dwellings in the community (the Hopkins Elder Housecall Program) or in a teaching nursing home (The Johns Hopkins Geriatrics Center). The 128 control subjects, a healthy ambulatory group, came from the Baltimore Longitudinal Study on Aging. All subjects were free of diseases or medications that might interfere with their vitamin D status.


METHODS
Serum levels of 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D (1,25-[OH]2D) were measured in all subjects. In a subgroup of 80 subjects, serum levels of intact parathyroid hormone (PTH), ionized calcium, and osteocalcin and intake of vitamin D (through 3-day food records) were assessed. A randomly selected cohort of sunlight-deprived subjects also had serum levels of vitamin D binding protein measured.


RESULTS
In sunlight-deprived subjects 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)2D level was 52 pmol/L (20 pg/mL) (range, 18 to 122 pmol/L [7 to 47 pg/mL]). In the sunlight-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 inverse relationship existed between 25-OHD (ie, Log [25-OHD]) and PTH when they were analyzed together (r = -0.42; R2 = 0.18; P < .001) and for each cohort separately. All other parameters measured, except ionized calcium, differed significantly from the Baltimore Longitudinal Study Group means. The mean (SD) daily intakes of vitamin D (121 [132] IU) and calcium (583 [322] mg) were below the recommended dietary allowance only in the community-dwelling homebound population. The mean vitamin D binding protein level in the sunlight-deprived subgroup was in the normal range.


CONCLUSIONS
Despite a relatively high degree of vitamin supplementation in the United States, homebound elderly persons are likely to suffer from vitamin D deficiency.
D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D018577:Homebound Persons; D006707:Homes for the Aged; D006801:Humans; D008297:Male; D008396:Maryland / Q000453:epidemiology; D009735:Nursing Homes; D015675:Osteocalcin / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood; D014807:Vitamin D / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*
D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D015675:Osteocalcin; D014807:Vitamin D; D002118:Calcium