Human Chorionic Gondadotropin is also known as hCG or beta-HCG. Tests for this substance may be used to confirm or monitor a pregnancy, detect an ectopic pregnancy or diagnose germ cell tumors of the ovaries and testes and gestational trophoblastic disease, or GTD. In patients who have previously had a tumor diagnosis, a beta-HCG tumor marker test may be used at regular intervals to check how effective the treatment has been or to detect tumors if they recur.

A physician may recommend a beta-HCG tumor marker test if he or she suspects that a patient may be suffering from a germ cell tumor or a tumor caused by GTD. People with these problems may suffer from vaginal bleeding, pelvic pain, excessive vomiting, an enlarged uterus or swollen masses in the body. Some people also suffer from weakness in the legs, constipation and incontinence.

Non-pregnant women and healthy men have undetectable levels of hCG. During pregnancy, the hCG level doubles every two to three days, though ectopic pregnancies may take longer to reach these levels. Longer hCG level doubling times may indicate a failing pregnancy, as well as effective treatment for germ cell tumors or GTD. Increased levels after treatment can mean that the disease is coming back.

Drinking too much water or other liquid before the test can produce a false negative on urine-based tests. Anti-parkinson drugs, tranquilizers, hypnotics and anti-convulsants can cause a false positive.