[Plasma zinc levels in elderly hospitalized subjects. Correlation with other nutritional and immunological markers and survival].

Plasma zinc levels were measured in 95 elderly patients hospitalized in a long stay unit and in 100 healthy controls under 65 years of age. Plasma zinc concentrations were significantly lower in the elderly patients, as compared to the younger subjects (p 0.001). The correlations with serum prealbumin (p 0.05) and serum albumin (p 0.05) concentrations and the frequent association with protein-calorie malnutrition suggest that the low serum zinc levels mirror a low dietary zinc intake. Immunological tests in the elderly show moderate lymphopenia, high serum IgA and frequent depression of delayed cutaneous hypersensitivity to DNCB and PHA. We find a significant correlation between plasma zinc concentration and peripheral blood lymphocyte counts, but not the other immunological parameters. Linear discriminant analysis shows that the association of low plasma zinc values, low serum protein concentration and high serum IgG concentration implies poor prognosis.