Human chorionic gonadotropin (hCG) is a glycoprotein with two non-covalently bound subunits. The alpha subunit is similar to those of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH).
The beta subunit of hCG differs from other pituitary glycoprotein hormones, which results in its unique biochemical and immunological properties. HCG is synthesized by the cells of the placenta and is involved in maintaining the corpus luteum during pregnancy. It is detected as early as one week after conception.
We use the Total HCG method for detecting ectopic pregnancy. In normal pregnancy, the levels of hCG increase exponentially for about 8 to 10 weeks after the last menstrual cycle. Later in pregnancy, about 12 weeks after conception, the concentration of hCG begins to fall as the placenta begins to produce steroid hormones.
Other sources of elevated hCG values are threatened abortion, tumours, and recent termination of pregnancy.
An initial HCG value of 10 – 25 u/L is inconclusive of pregnancy and should be repeated after 24 hours.
An initial HCG value greater than 25 u/L indicates pregnancy.
- Three patient identifiers from
- N.H.S. number
- Unit Number