Immunological function and nutritional assessment.

Theoretically, a large number of tests of immunologic functions could be used for nutritional assessment. However, many of these immunologic tests require specialized laboratory skills and take a long time to perform. These tests provide little additional information to the clinician concerning the nutritional status of the patient, compared to the data that can be obtained from a few simple, selected immunologic measurements. Only a few immunologic tests are sufficiently simple, reproducible, and reliable indicators of nutritional status to be of practical value for routine nutritional assessment. These are the total lymphocyte count and skin tests. At present, all of the other immunologic measurements that have been reviewed should be considered as research tools for nutritional assessment. Immunological tests can be affected by many clinical variables unrelated to nutrition, such as specific pathologic conditions, immunodepressive therapies, accidental or surgical trauma, and infection, and this fact should be considered when using immunological tests to assess nutritional status. Malnutrition suppresses the acute-phase response of plasma proteins. The measurement of the acute-phase response of selected acute-phase proteins can be a functional measurement of nutritional status.