Measurement of Total Protein Is Not a Useful Inclusion in Liver Function Test Profiles

Abstract

Biochemical and hematological pathology investigations often are requested using groupings or profiles of tests. In Australia, “liver function test” (LFT) is recognized by legislation (1) and consists of six or more tests, including alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, albumin, (total) bilirubin, γ-glutamyl transpeptidase, lactate dehydrogenase, and (total) protein. Historically, although total protein has been included as a part of LFT, the total protein measurement is not specific for abnormal liver function or liver damage. We have examined whether the routine inclusion of total protein as a component of LFT leads to new diagnoses or alters patients’ clinical management. At the time of this study, our laboratory primarily serviced a large, tertiary referral university teaching hospital. Total protein was measured using the Biuret method (2) on a Hitachi 747 analyzer (Boehringer-Mannheim/Roche Diagnostics). Using a computer, we examined 15 000 consecutive unselected requests, including ambulatory and hospitalized patients, received by our laboratory over a 3-month period in which the requesting clinician had specified (among other things) that a “LFT” biochemical profile was to be performed. From this sample population of 15 000 LFT requests, …