Determination of Tumor Markers in Serum. Pitfalls and Good Practice

Abstract

Although serum total sialic acid has been shown to be a cardiovascular risk factor, with elevated levels associated with increased cardiovascular mortality and also with cerebrovascular disease, the reason for the elevation in serum sialic acid content remains obscure. It has been shown that an increased output of serum proteins by the liver due to some type of acute phase reaction may be one of the possible sources of an increased serum sialic acid concentration in patients with myocardial infarction. An increase in the activity of sialidase, which cleaves the terminal sialic acid residues from oligosaccharides, glycoproteins and gangliosides, may also play an important role in the elevation of serum total sialic acid in myocardial infarction. Elevated serum total sialic acid in the blood might result either from the shedding or secreting of sialic acid from the cell membrane surface, or releasing of cellular sialic acid from the cell into the bloodstream due to cell damage after myocardial infarction. The purpose of the present study is to investigate serum total and lipid-bound sialic acid and the enzymes serum lactate dehydrogenase, creatine kinase and aspartate aminotransferase in patients with acute myocardial infarction, at 24 h post-infarction (day 1), 48 h post-infarction (day 2) and 72 h post-infarction (day 3). A possible role of cell damage in the elevation of serum total and lipid-bound sialic acid levels in these patients was also evaluated. In this study, 40 patients with myocardial infarction ranging in age from 42 to 68 years, and 26 healthy volunteers ranging in age from 45 to 71 years were included. Serum total sialic acid determination was carried out by the thiobarbituric acid method of Warren and lipid-bound sialic acfd by the method of Katopodis. Our data shows that a) there is a gradual increase in the levels of serum total sialic acid and lipid-bound sialic acid during the first three days after the acute myocardial infarction and b) the elevation in serum total sialic acid levels correlates with the elevation in lactate dehydrogenase activity only on day 1 following infarction. Therefore, either the shedding or secreting of sialic acid from the cell or cell membrane surface may be partly responsible for an increased serum sialic acid concentration especially on day 1 following myocardial infarction.

Kallikrein-related peptidases (KLKs): a gene family of novel cancer biomarkers

“…However, despite its high popularity as a screening biomarker, the usefulness of the PSA test is still under examination. The major drawback of the use of this test is its relatively low specifi city, especially in screening programs when high sensitivity is needed (80) . In addition, to serum total PSA (tPSA), recent clinical trials uncovered the predictive potential of serum free PSA (fPSA) in terms of the aggressiveness of the disease and patients ' outcome.…”

Laboratory medicine and medical oncology: the tale of two Cinderellas

“…Much has been said about misuses of tumor marker determination in clinical practice [32] , sometimes culminating in what has been termed as " tumor marker terrorism " . In fact, virtually all tumor markers currently used in routine practice may be increased in a range of benign disorders as recently comprehensively reviewed by Trap e et al [8] .…”

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Clinical Practice: Quality Requirements1

“…In addition to adhering to general preanalytical recommendations applicable to all diagnostic tests (2) and encouraging appropriate test requesting (1, 3, 4), the laboratory must exercise extra vigilance in ensuring that correct results are reported (5). Errors reportedly occur more often in the preanalytical than the analytical phase [30%–75% and 13%–31%, respectively, as reported in one review (6), and 10 times as often in a transfusion medicine study (7)].…”