Definition
- Glycoprotein hormone, which is also known as Ž ²-hCG and chorionic gonadotropin, is produced by the placenta, with structural similarity to the pituitary hormones FSH, TSH, and LH. The hCG test is widely used to detect pregnancy. It is also used as tumor marker for choriocarcinoma and some germ cell tumors.
- Normal range: ≥5.0 mIU/mL (generally indicative of pregnancy; Table 16.40).
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TABLE 16 " “40Representative Ranges in Human Chorionic Gonadotropin (hCG) During Normal PregnancyView LargeTABLE 16 " “40Representative Ranges in Human Chorionic Gonadotropin (hCG) During Normal Pregnancy Approximate Gestational Age (weeks postconception) Approximate hCG Range (mIU/mL) 0.2 " “1 5 " “50 1 " “2 50 " “500 2 " “3 100 " “5,000 3 " “4 500 " “10,000 4 " “5 1,000 " “50,000 5 " “6 10,000 " “100,000 6 " “8 15,000 " “200,000 8 " “12 10,000 " “100,000
Use
- Diagnosis of pregnancy
- Investigation of suspected ectopic pregnancy
- Monitoring in vitro fertilization patients
Interpretation
Increased In
- Normal pregnancy
- Recent termination of pregnancy
- Gestational trophoblastic disease
- Choriocarcinoma and some germ cell tumors
- Hydatiform mole
Decreased In
- Threatened abortion; microabortion
- Ectopic pregnancy
Limitations
- False elevations (phantom hCG) may occur with patients who have human antianimal or heterophilic antibodies.
- Patients who have been exposed to animal antigens, either in the environment or as part of treatment or an imaging procedure, may have circulating antianimal antibodies present. These antibodies may interfere with the assay reagents to produce unreliable results.