Prediction of whole blood selenium levels in patients on long-term parenteral nutrition.

In an attempt to define clinical variables which might predict the whole blood selenium level prior to supplementation, whole blood selenium levels were determined in 21 home parenteral nutrition patients who were not receiving selenium supplementation. These levels were examined for possible correlations by single and multivariant analysis with the following clinical parameters: age at initiation of home parenteral nutrition, months of home parenteral nutrition received, hematocrit, albumin, estimated length of remaining small bowel, kilocalories per kilogram actual body weight infused per day, grams protein per kilogram actual body weight infused per day, and multiple of ideal body weight. Of all the combinations of variables examined, the best correlation obtained was between whole blood selenium levels and the total kilocalories per kilogram body weight per day delivered intravenously (r = -0.89, p less than 0.001). A statistically significant correlation (r = -0.67, p less than 0.01) was also observed between selenium levels and the grams protein per kilogram actual body weight infused per day. However, inclusion of this or additional variables did not increase the predictive value of the equation describing whole blood selenium levels as a function of the calories delivered. The implication of this study is that patients requiring more intensive nutritional support develop lower selenium levels during the course of treatment. Despite these correlations, no single clinical parameter or combination of parameters, however, was of sufficient predictive value to preclude laboratory determination of whole blood selenium values in deciding which patients might benefit from selenium supplementation.