Calcium metabolism in the frail elderly

Abstract

Elderly residents of aged care facilities are usually considered at high risk of osteoporosis not only due to their age, but also due to nutritional factors, poor sunlight exposure and renal insufficiency. This study aimed to describe calcium metabolism and related hormones in this high-risk population. A total of 1280 elderly residents of hostels and nursing homes in the northern Sydney area (aged 65 years or over) had serum analysis for clinical chemistry including serum 25-hydroxy vitamin D (25OHD) and parathyroid hormone (PTH). Moderate renal impairment (creatinine clearance 30-60 ml/min) was common (62%), but hypocalcaemia was uncommon (7.0%). Mild hypoalbuminaemia was common (34% below 40 g/l, but only 3.2% below 35 g/l); 77.5% of the cohort had low serum 25OHD levels (<39 nmol/l) and 41.7% had elevated PTH levels (>66 pg/ml). Independent predictors of low serum 25OHD levels included gender, age, serum PTH, season, mobility and creatinine clearance. Use of vitamin D supplementation conferred modestly higher serum 25OHD levels (45.5 vs 27.1 nmol/l in non-supplemented residents, p < 0.0001) and lower PTH levels (50.0 vs 78.1 pg/ml, p < 0.0001). Despite adequate overall nutrition, vitamin D deficiency is present in the majority of this population. Vitamin D deficiency remains a significant public health problem in the institutionalized frail elderly. Currently available supplements are not adequate or utilized frequently enough to address this problem.