Prevalence of vitamin D insufficiency in elderly ambulatory outpatients in Denver, Colorado.

BACKGROUND

Vitamin D insufficiency is common in the elderly. However, previous studies have utilized 25-hydroxvvitamin D (25[OH]D) concentrations as low as <16 ng/mL for defining vitamin D insufficiency. Moreover, most of the studies have been conducted in European patients, in certain geographic areas of the United States, or in institutionalized elderly.

OBJECTIVE

The goal of this study was to characterize vitamin D concentrations in ambulatory elderly living in metropolitan Denver, Colorado, utilizing 25(OH)D concentrations <32 ng/mL as the definition for vitamin D insufficiency.

METHODS

Ambulatory older adults (aged 65-89 years) with clinic visits during December 2005 and January 2006 were enrolled. Serum concentrations of 25(OH)D, parathyroid hormone (PTH), calcium, phosphorus, creatinine, and albumin were measured; height and weight were also measured. Data regarding dietary and over-the-counter vitamin D intake were collected, as well as information on body mass index, history of osteoporosis, osteoporosis treatment, and history of falls and fractures.

RESULTS

Eighty patients (mean [SD] age, 77.8 [5.3] years; age range, 66-89 years) completed the study; there were no dropouts. The majority of patients were white (88%) and female (68%). Fifty-nine (74%) were found to have vitamin D insufficiency. Mean total and over-the-counter vitamin D intake was significantly higher in sufficient (P < 0.01) and insufficient (P < 0.05) patients compared with deficient patients, but dietary intake did not differ significantly between groups. The majority of patients who were vitamin D insufficient consumed more than the recommended 400 to 600 IU/d of vitamin D. Obese patients were found to have significantly lower 25(OH)D concentrations (P < 0.001) and higher PTH concentrations (P = 0.04) than nonobese patients.

CONCLUSIONS

Vitamin D insufficiency is prevalent in ambulatory, and especially obese, elderly living in Denver, Colorado, despite vitamin D intake consistent with national recommendations. Dietary intake of vitamin D appeared to be unreliable to prevent insufficiency. Based on our results, along with other published data, we feel that national recommendations for vitamin D intake in the elderly should be increased to at least 800 to 1000 IU/d of over-the-counter supplemental cholecalciferol.