Vitamin D deficiency and secondary hyperparathyroidism: clinical and biochemical associations in older non-institutionalised Southern Tasmanians

Aim: To determine the prevalence and associations of vitamin D (25-OHD) def iciency in a sample of older Tasmanian subjects. Methods: A cross-sectional survey of: 109 patients with a mean age of 79 ye ars (range 60-101 years) consecutively admitted to a short stay geriatric r ehabilitation ward; 52 community dwelling subjects with a mean age of 75 ye ars (range 64-88 years). Subjects answered a questionnaire, had anthropomet ric measurements and underwent venepuncture. Results: The main outcome measure was 25 hydroxy vitamin D (25-OHD) level w ith deficiency defined as <28 nmol/L. Vitamin D deficiency was found in 67% and secondary hyperparathyroidism in 49% of the hospitalised group. Vitami n D deficiency was also found in 17% of the community group, in particular one in three residents of Independent Living Units was deficient. Subjects who were deficient were older (80 years vs 76 years [p<0.001]), had lower b ody mass index (23.7 kg/m(2) vs 25.9 kg/m(2) [p<0.001]) and had a lower ser um albumin (35 gm/L vs 39 gm/L [p<0.001]). Deficient subjects had poorer ph ysical functional status (p=0.02) and lower activity levels (p<0.001) and r eported less habitual sun exposure (p<0.001). Biochemical measures such as parathyroid hormone, alkaline phosphatase and calcium were weakly predictiv e of vitamin D levels. By stepwise multiple regression analysis, the only s ignificant predictors of vitamin D levels were the Frenchay Activity Index, albumin and calcium. Conclusion: Vitamin D deficiency and secondary hyperparathyroidism is commo n in community living older people who are hospitalised in Southern Tasmani a and is associated with increasing age, poor physical function and activit y and low reported sun exposure.