An elevated HCG, or human chorionic gonadotropin, usually means that you are pregnant. Pregnancy tests use an elevated level of HCG as a marker because HCG is always present in high levels during the first trimester of a normal pregnancy. The purpose of this hormone is to protect the pregnancy by stimulating other necessary hormones. However, there are some instances that can trigger a false-positive result or that cause your HCG level to increase.
Pregnancy
The popular home pregnancy tests and the urine tests used in clinics are qualitative; they accurately detect the presence of HCG in the urine. Some react to an HCG level of as little as 20 milliunits per milliliter, which is about twice the highest normal non-pregnant level, according to SydPath from St. Vincent's Hospital in Sydney. It is a very specific test and a very sensitive test. The blood serum test is often done to verify the results of the urine test and determine the actual amount of HCG present. This information is useful in detecting problems or higher risks with a pregnancy, such as an ectopic pregnancy or multiple pregnancy. Carefully follow the directions for home pregnancy tests. The amount of HCG needed to produce a positive home pregnancy test is only normal in a pregnant woman.
Drugs
Certain drugs, such as chlorpromazine, phenothiazine, promethazine and methadone, can cause a false-positive test result when measuring HCG, notes Jacques Burton Wallach, author of "Interpretation of Diagnostic Tests." Promethezine can also cause a false-negative result.
Contamination
Urine HCG tests may show false elevations if there is a urinary tract infection. Wallach says that the bacteria causing the infection will contaminate the urine, precipitating a reading of a false elevation. Other contaminants, such as blood or protein can create a similar effect.
Cancer
An elevation of HCG in a woman who is not pregnant can indicate a pre-malignant condition or a malignancy. The variation in the levels can also monitor the status of specific malignancies. In men who have testicular cancer or who have had their testicles removed, an elevated level may occur. The presence of HCG in cerebrospinal fluid can indicate cancer has metastasised to the brain.
References
- "Interpretation of Diagnostic Tests"; Jacques Wallace, M.D.; 2000
- "Clinical Chemistry"; "Background" Human Chorionic Gonadotropin in Healthy, Nonpregnant Women; Laurence A. Cole; 2005
- "Molecular Cancer"; Reduction of Human Chorionic Gonadotropin Beta Subunit Expression by Modified U1 snRNA Caused Apoptosis in Cervical Cancer Cells; Anna Jankowska et al; 2008
- SydPath: hCG in Pregnancy
- Cancer Research UK: Testicular Cancer Tests
