[Study of vitamin D deficiencies in the aged].

Plasma levels of 25-hydroxycalciferol (25-OH-D) and the biological parameters of phosphocalcium metabolism were determined in 55 patients institutionalized in a geriatric hospital in Geneva. They were compared with two control groups, one of the same age and the other younger. The mean plasma 25-OH-D level of the hospitalized patients was 22.7 +/- SD 13.6 microgram/l, which is significantly lower (p less than 0.001) than the mean level obtained from both the control group of the same age (46.2 +/- SD 20.1 microgram/1 25-OH-D) and the control group of young subjects (48.6 +/- SD 16.8 microgram 25-OH-D/1). Among the 55 hospitalized patients, 27 (49%) had a deficient 25-OH-D plasma level lower than 20 microgram/1. Compared to the control group of the same age, the group of hospitalized subjects had lower mean plasma level of inorganic phosphate (27.1 +/- SD 4.34 mg/1; p less than 0.01) and an elevated mean plasma level of alkaline phosphatase (46.9 +/- SD 16.5 UI/1; p less than 0.005). For those 27 patients deficient in 25-OH-D, a positive correlation exists between the plasma values of 25-OH-D and the total calcium (r = 0.584). The high incidence of biological indicators of osteomalacia found in the group of hospitalized patients suggests that vitamin D deficiency is a current problem of the elderly in Switzerland necessitating a review of the prophylactic measures now in use.