Prevalence and biological consequences of vitamin D deficiency in elderly institutionalized subjects

The prevalence of vitamin D deficiency was evaluated in a population of elderly institutionalized subjects in seven long-term geriatric care facilities in France (Amiens, Francheville, Ivry, Lille, Montpellier, Oissel and Villejuif). Residents whose functional capability was relatively good were entered into the study. There were 126 patients (99 females and 27 males) with a mean age +/- SD of 84 +/- 6.6 years. All subjects had been institutionalized for over six months and were capable of walking at least as far as the dining room. None had received vitamin D or other compounds known to affect the metabolism of phosphorus and calcium within six months before the study. Vitamin D status was evaluated by determining serum 25 hydroxyvitamin D (25 OH D) levels using a radiocompetition assay after extraction and chromatographic separation. Mean serum 25 OH D was 3.17 +/- 2.52 ng/ml (median 2.5). Eighty-five per cent of subjects had serum 25 OH D values of less than 5 ng/ml and 98% had values under 10 ng/ml, which is the cutoff usually taken to define vitamin D deficiency. Mean serum levels of intact parathyroid hormone were increased approximately two-fold as compared with values in healthy adults (70 +/- 39 pg/ml versus 33 +/- 12 pg/ml). Biochemical markers for bone formation (alkaline phosphatase, osteocalcin) and bone resorption (TRAP, hydroxyproline, pyridinoline) were all increased, with mean values 1.4-fold to 3.4-fold those seen in healthy adults. Serum 25 OH D levels were negatively correlated with serum intact parathyroid hormone levels (r = 0.41; p < 0.0001). Serum intact parathyroid hormone levels were positively correlated with alkaline phosphatase activity (r = 0.30; p < 0.001) and serum osteocalcin levels (r = 0.36; p < 0.0001) and negatively correlated with corrected serum calcium levels (r = -0.20; p < 0.02). Conclusion. Our data demonstrate that severe vitamin D deficiency is present in virtually all elderly institutionalized subjects and is accompanied with secondary hyperparathyroidism responsible for increases in markers of bone remodeling. Routine vitamin D supplementation is warranted in elderly institutionalized subjects.