Laboratory values in the elderly. Are they different?

Abstract

Diseases do not always show the usual or "classic" signs and symptoms in the elderly. Physiologic changes over the years of a long life seem to be responsible for impairment of regulation or function of many organ systems. Since function often is measured in clinical medicine by laboratory testing, physicians frequently face difficult clinical decisions as to the need for further evaluation of a patient based upon a laboratory test result received. For the most part, the laboratory values obtained in elderly persons seem to fall into our traditional or so-called normal ranges, and little evidence supports the need for separate sets of reference ranges for the elderly. A few patients do show abnormalities on specific tests, and a few test values can be expected more frequently than others to be out of line in healthy elderly individuals, specifically: serum alkaline phosphatase (elevations to about 2.5 times the normal) fasting blood glucose (up to 135 to 150 mg/dl) postprandial blood glucose or oral glucose tolerance test (increased above normal to 10 mg/dl per decade of age) normal serum creatinine with the existence of markedly decreased creatinine clearance higher erythrocyte sedimentation rates (up to 40 mm/hr) hemoglobin (lowest acceptable level is 11.0 gm/dl in women; 11.5 gm/dl in men) BUN (up to 28 to 35 mg/dl) The presence of multiple diseases in elderly patients, as well as the many medications often taken, will no doubt be more of a source of confusion and consternation in the clinical correlation of laboratory test results than the lack of adequate reference ranges specifically compiled for the elderly. The question "What test result is significant and raises suspicion of disease?" will remain a part of that all-important integration and correlation of the information available to the physician for the diagnosis and treatment of the patient.