To the Editor: Although treatment with vitamin D has been shown to reduce hip fracture risk in elderly institutionalised people,1 there has been a perception that vitamin D deficiency is generally uncommon in countries with high sunlight exposure such as Australia.

We studied the prevalence of vitamin D deficiency in older people in residential aged-care facilities (hostels and nursing homes) in the northern Sydney area as part of the FREE study (Fracture Risk Epidemiology in the Elderly), a prospective study of fracture incidence in more than 2000 participants. Here, we report baseline serum 25(OH) vitamin D concentrations in the first 386 participants, determined in partially purified lipid extracts using a competitive protein binding assay.2

The sample comprised 252 women and 134 men (mean ± SE age, 86.7 ± 0.6 v 81.2 ± 0.7 years, respectively; P < 0.001). The mean serum 25(OH)D level was 17 nmol/L (SD, 12) and median serum 25(OH)D level was 15 nmol/L (interquartile range, 9 to 22). Vitamin D deficiency (defined as a serum 25(OH)D concentration < 28 nmol/L) was present in 86% of women and 68% of men. There was no significant difference in serum vitamin D levels between women in nursing homes versus women in hostels, nor between men in nursing homes versus those in hostels. Although serum vitamin D levels were low throughout the year, a small rise was observed in summer (P < 0.01). Length of stay in the residential facility was not a predictor of serum vitamin D level. Mean parathyroid hormone levels were 93 pg/mL (normal range, 12–72 pg/mL) and rose when vitamin D levels dropped below 21 nmol/L, indicating secondary hyperparathyroidism.

A number of previous studies have suggested a high prevalence of vitamin D deficiency in older institutionalised Australians in southern States,2-4 but we are unaware of any published studies in Sydney (latitude 33°S). However, as the prevalence of vitamin D deficiency in older people living in the community in Geelong is low,5 our study suggests that factors like confinement indoors is more important than latitude.

Given the relationship between vitamin D status and fracture, with more than 72 500 nursing home residents and 60 200 hostel residents in Australia in 1997, our findings indicate that vitamin D deficiency represents a significant public health problem in elderly institutionalised Australians regardless of geographical location. Importantly, this problem could be solved relatively simply by measures such as a short period of daily sunlight exposure or giving moderate doses of vitamin D annually to nursing home and hostel residents.