During pregnancy, the body begins to produce the hormone HCG, or human chorionic gonadotropin. It is secreted by the placenta following implantation of the embryo in the uterine wall. An HCG test is used to confirm pregnancy and later on it may be ordered by your physician to keep tabs on the progression of the pregnancy. An HCG test is also used to determine the presence of certain tumors in women and men. HCG can be detected via a urine or blood test.
HCG Levels
HCG levels are typically not detectable unless you are pregnant. After fertilization of the egg, the cells forming the placenta begin increasing production of HCG. Increased levels of HCG can be detected using a blood test around 11 days after conception and by a urine test 12 to 14 days after conception. In the early part of pregnancy, HCG levels double approximately every 48 to 72 hours. After 11 weeks, HCG levels drop gradually for the remainder of the pregnancy. Each woman's HCG levels vary, so an ultrasound is generally a better indicator of how the pregnancy is progressing. However, as a rule of thumb, the American Pregnancy Association states an HCG level lower than 5mIU/ml is negative for pregnancy, and levels above 25mIU/ml are indicative of pregnancy.
HCG Testing
Waiting can be very frustrating, but for the most accurate result, MayoClinic.com recommends you wait until one week after a missed period before taking a home pregnancy test. Home pregnancy tests can accurately detect HCG one week after a missed period. They are available at most any pharmacy or supermarket. Sometimes, it may be necessary to have a blood test for HCG performed at a lab. This can be the case if your doctor suspects you have an ectopic pregnancy or have suffered an early miscarriage. Blood tests for HCG are also ordered when certain tumors are suspected.
Abnormal HCG Levels
Although the results are not always definitive, abnormal levels of HCG can be indicative of certain problems with your pregnancy or health. When HCG levels are higher than normal, it can indicate malignancies such as hydatidiform mole of the uterus or choriocarcinoma of the uterus. High levels can also indicate the presence of twins or triplets, ovarian cyst or ovarian cancer. MedlinePlus states an HCG test is also used in men to determine the presence of testicular cancer. Lower than normal HCG levels can be an indicator for an ectopic pregnancy, imminent miscarriage or death of the fetus. However, abnormal HCG levels can also occur in completely normal pregnancies that result in the birth of a healthy baby.
False Results
There are some things that can affect the results of either a urine or blood test for HCG. If you are taking a home pregnancy test, limit the amount of fluids you drink beforehand as it can dilute your urine enough to produce a false negative reading. Certain medications, including diuretics and antihistamines, can also create a false negative result. Fertility drugs, anti-convulsant and Parkinson's medications can cause a false positive result. Check with your doctor if you have any doubts.
