Chorionic Gonadotropin, Beta-Subunit (Quantitative), Spinal Fluid
Facilitating diagnosis of brain metastases of testicular cancer or extragonadal intracerebral germ cell tumors
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Human chorionic gonadotropin (hCG) is synthesized during normal gestation by cells of the fetal syncytiotrophoblast. hCG may also be produced by neoplastic cells of:
-Testicular tumors, either seminomas or nonseminomas
-Ovarian germ cell tumors
-Gestational trophoblastic disease (GTD), hydatidiform mole, and choriocarcinoma
-Various nontrophoblastic tumors, including breast, ovarian, pancreatic, cervical, gastric, and hepatic cancers
hCG is a glycoprotein hormone composed of 2 dissimilar subunits:
-An alpha-polypeptide (92 amino acids, molecular weight 14,000) that is common among 3 other pituitary glycoprotein hormones; follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid-stimulating hormone (TSH)
-A unique beta-polypeptide (145 amino acids, molecular weight 22,200) which determines the biologic activity of hCG
Only the intact hormone is biologically active; the individual subunits have no biological activity. The beta-subunit of hCG may be produced independently of the alpha-subunit by both normal and neoplastic cells. This assay measures both free beta subunit and intact hCG.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Tumor markers are not specific for malignancy, and values may vary by method.
Elevated levels of human chorionic gonadotropin in spinal fluid indicate the probable presence of central nervous system metastases or recurrence of tumor in patients with germ cell tumors, including patients with testicular cancer or choriocarcinoma.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Slight elevations of human chorionic gonadotropin (hCG) in spinal fluid may occur in non neoplastic diseases.
Measurement of hCG in spinal fluid should not be relied upon exclusively to determine the presence of central nervous system metastases in patients with germ cell tumors.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Bagshawe KD: Choriocarcinoma. A model for tumor markers. Acta Oncol 1992;31:99-106
2. Mann K, Saller B, Hoermann R: Clinical use of hCG and hCG beta determinations. Scand J Clin Lab Invest 1993;216:97-104
3. Ozturk M, Bellet D, Manil L, et al: Physiological studies of human chorionic gonadotropin (hCG), alpha hCG, and beta hCG as measured by specific monoclonal immunoradiometric assays. Endocrinology 1987;120:549-558