Human Chorionic Gonadotropin (hCG), Beta Subunit, Quantitative, Serum
| Human Chorionic Gonadotropin (hCG), Beta Subunit, Quantitative, Serum | | | |
| Number | | 004416 |
| CPT | | 84702 |
| Synonyms | | Beta-hCG Quantitative, Serum ; hCG Quantitative, Serum |
| Special Instructions | | Values obtained with different assay methods should not be used interchangeably in serial testing. It is recommended that only one assay method be used consistently to monitor each patient's course of therapy. This procedure does not provide serial monitoring; it is intended for one-time use only. If serial monitoring is required, please use the serial monitoring number 480038 (see test below) to order. |
| Specimen | | Serum |
| Volume | | 1 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 | | Plasma specimen; gross hemolysis |
| Reference Interval | | Male and nonpregnant female: 99% have values <10 mIU/mL |
| Use | | 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). |
| Methodology | | Immunochemiluminometric assay (ICMA) |
| Additional Information | | Human chorionic gonadotropin, a glycoprotein hormone, which is normally produced by the developing placenta, and aberrantly produced by some germ cell neoplasms, is composed of glycopeptide α- and β-subunits. The α-subunit, a 92-amino acid sequence, is identical with that of luteinizing hormone, follicle stimulating hormone, and thyroid-stimulating hormone. The β-subunit, a 145 amino acid sequence, is unique to hCG and specific tests for it are not subject to hormonal cross reactivity. Chorionic gonadotropin assays are sometimes used to support the diagnosis of ectopic pregnancy. Ectopic gestations do not develop or secrete hCG as do intrauterine pregnancies. Abnormal hCG levels coupled with transvaginal ultrasound detect many ectopic pregnancies prior to rupture.1 hCG levels are extremely useful in following those germ cell neoplasms which produce hCG, particularly trophoblastic neoplasms. Following evacuation of a trophoblastic lesion, hCG β-subunit should fall to normal in 6-8 weeks and stay there. Oral contraceptive use may delay this fall. Any other delay in the fall, or subsequent rise, is an indication for other further evaluation. In germ cell neoplasms in the male, β-hCG and α-fetoprotein are both useful tumor markers. They can be demonstrated histochemically in tissue to confirm diagnosis, and can be followed in serum to evaluate recurrence. |
| Footnotes | | - DiMarchi JM, Kosasa TS, and Hale RW, “What Is the Significance of the Human Chorionic Gonadotropin Value in Ectopic Pregnancy?” Obstet Gynecol, 1989, 74(6):851-5
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| References | | Deligdisch L, Driscoll SG, and Goldstein DP, “Gestational Trophoblastic Neoplasms: Morphologic Correlates of Therapeutic Response,” Am J Obstet Gynecol, 1978, 130(7):801-6. Khazaeli MB, Buchina ES, Pattillo RA, et al, “Radioimmunoassay of Free Beta-Subunit of Human Chorionic Gonadotropin in Diagnosis of High-Risk and Low-Risk Gestational Trophoblastic Disease,” Am J Obstet Gynecol, 1989, 160(2):444-9. Morinaga S, Ojima M, and Sasano N, “Human Chorionic Gonadotropin and Alpha-Fetoprotein in Testicular Germ Cell Tumors. An Immunohistochemical Study in Comparison With Tissue Concentrations,” Cancer, 1983, 52(7):1281-9. Tyrey L, “Human Chorionic Gonadotropin Assays and Their Uses,” Obstetrics and Gynecology Clinics of North America, Volume 15, Philadelphia, PA: WB Saunders Co, 1988, 457-75. |
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