[Laboratory findings in elderly patients: a forgotten aspect of laboratory medicine?]

Reference values, which would be related to the individual "biological age" and which would be needed for laboratory investigations of geriatric patients, are at the moment not usual. Thereafter, for rational interpretation of laboratory results, the knowledge of "preanalytical variations" is of crucial importance. These are systematically discussed in the present contribution. In principle, one distinguish between "biological variations" and "preanalytical errors". The first are characterized by the following "factors": "permanent" (age, genetics), "long time" (age), "intermediate" (life style, climate, nutrition), and "short time" (circadian, postprandial, and orthostatic effects). The significance of "preanalytical errors" is accentuated by the fact that many of "geriatric institutions" are serviced by the laboratories, which are not situated close to them.