It is also used when an abnormal condition that can elevate HCG level is suspected. A pregnancy test is usually based on detection of HCG, which is secreted by the trophoblast after the ovum is fertilized. HCG appears in the blood and urine of pregnant women as early as 10 days after conception. HCG has a similar to function to LH in stimulating secretion of estrogen and development of the placenta. However, HCG may also be elevated in abnormal circumstances in men as well as women.
Levels vary with gestational age during pregnancy .
Drugs that can increase HCG measurements include anticonvulsants, antiparkinsonian drugs, phenothiazine, and promethazine. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.