Human Chorionic Gonadotropin (hCG), β-Subunit, Qualitative, Serum

Human Chorionic Gonadotropin(hCG), β-Subunit, Qualitative, Serum

CPT Test code: 84703

Specimen: Serum
Volume: 0.8 mL
Minimum Volume: 0.3 mL (Note: This volume does not allow for repeat testing.)
Container: Red-top tube or gel-barrier tube
Collection: If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions: Refrigerate
Causes for Rejection: Citrate plasma specimen; improper labeling
Reference Interval: Negative: <6 mIU/mL
Use: This test can be used for the early detection of and on-going monitoring of pregnancy. Determine the presence of hCG in patients with gestational trophoblastic disease; evaluate and monitor male patients with testicular tumors; follow up molar pregnancy. The quantitative hCG assay should be used for nonroutine detection of hCG (eg, ectopic pregnancy, threatened abortions, miscarriages, or very early pregnancy).
Limitations: In patients receiving therapy with high biotin doses (ie, >5 mg/day), no sample should be taken until at least eight hours after the last biotin administration.1 As with all tests containing monoclonal mouse antibodies, erroneous findings may be obtained from samples taken from patients who have been treated with monoclonal mouse antibodies or who have received them for diagnostic purposes.1 In rare cases, interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur.1 The test contains additives, which minimize these effects.
Additional Information: Similarly to LH, FSH, and TSH, human chorionic gonadotropin (hCG) is a member of the glycoprotein family and consists of two subunits (α- and β-chains) which are associated to the intact hormone. The α-chains in all four of these glycoprotein hormones are virtually identical, whereas the β-chains have greatly differing structures and are responsible for the respective specific hormonal functions.

hCG is produced in the placenta during pregnancy. In nonpregnant women, it can also be produced by tumors of the trophoblast, germ cell tumors with trophoblastic components, and some nontrophoblastic tumors.

Human chorionic gonadotropin consists of a number of isohormones with differing molecular size. The biological action of hCG serves to maintain the corpus luteum during pregnancy. It also influences steroid production. The serum of pregnant women contains mainly intact hCG.

Measurement of the hCG concentration permits the diagnosis of pregnancy just one week after conception. The determination of hCG in the first trimester of pregnancy is of particular importance. Elevated values here serve as an indication of chorionic carcinoma, hydatiform mole, or multiple pregnancy. Depressed values indicate threatening or missed abortion, ectopic pregnancy, gestosis or intrauterine death.

Elevated hCG concentrations not associated with pregnancy are found in patients with other diseases, such as tumors of the germ cells, ovaries, bladder, pancreas, stomach, lungs, and liver.2,3

Footnotes: 1. Human Chorionic Gonadotropin (hCG) on Elecsys 1010/2010 and Modular Analytics E170, package insert 2007-09, V 11, Indianapolis, IN: Roche Diagnostics, 2007.

2. Sturgeon CM, McAllister EJ, “Analysis of hCG: Clinical Applications and Assay Requirements,” Ann Clin Biochem, 1998, 35(Pt 4):460-91.PubMed 9681050

3. Marcillac I, Troalen F, Bidart JM, et al, “Free Human Chorionic Gonadotropin Beta Subunit in Gonadal and Nongonadal Neoplasms,” Cancer Res, 1992, 52(14):3901-7.PubMed 1377600

References: Hoermann R, Berger P, Spoettl G, et al, “Immunological Recognition and Clinical Significance of Nicked Human Chorionic Gonadotropin in Testicular Cancer,” Clin Chem 1994, 40(12):2306-12.PubMed 7527309

Runnebaum B, Rabe T, “Gynäkologische Endokrinologie, Grundlagen, Physiologie, Pathologie, Prophylaxe, Diagnostik, Therapie,” Berlin, Heidelberg, New York, London, Paris, Tokyo: Springer Verlag, 1987, 8:43, 489-541.

Schwarz S, Berger P, Wick G, “The Antigenic Surface of Human Chorionic Gonadotropin as Mapped by Murine Monoclonal Antibodies,” Endocrinology, 1986, 118(1):189-97.PubMed 2416550

Thomas CMG, Reijnders FJL, Segers MFG, et al, “Human Choriogonadotropin (hCG): Comparisons Between Determinations of Intact HCG, Free HCG β-Subunit, and “Total” hCG + β in Serum During the First Half of High-Risk Pregnancy,” Clin Chem, 1990, 36(4):651-65.