Human chorionic gonadotropin

Human chorionic gonadotropin (hCG) is a hormone created during the early part of pregnancy. The hCG production plays a critical role in the pregnancy development. Human chorionic gonadotropin is responsible for:

- prevention the disintegration of the corpus luteum
- progesterone production by the corpus luteum;
- endometrium development during first trimester of pregnancy;
- stimulation/development of fetal gonads and androgen synthesis by the fetal testes;
- stimulation the secretion of estrogens and development of the placenta.

All above mentions functions are absolutely crucial for normal pregnancy development.

hCG additional functions:

hCG affects the immune tolerance of the pregnancy;
hCG is an important tumor marker especially (with clinical significance) in Gestational trophoblastic disease.

In healthy not pregnant women the hCG levels are normally undetectable. During early pregnancy, the hCG level in the blood doubles every two to three days. Ectopic pregnancies usually have a longer doubling time. Those with failing pregnancies will also frequently have a longer doubling time or may even show falling hCG concentrations. In most cases the rapid drop of hCG is correlating with miscarriage – the hCG concentration is dropping down rapidly following the miscarriage. If hCG does not fall to undetectable levels, it may indicate remaining hCG-producing tissue that will need to be removed (molar pregnancy and/or trophoblastic tumors).

hCG is also used to monitor treatment in patients with trophoblastic disease and to detect recurrent disease after treatment is complete. During therapy, a falling hCG level generally indicates that the cancer is responding to treatment, while rising levels may indicate that the cancer is not responding to therapy. Increased hCG levels after treatment may indicate a recurrence of disease.

Most home pregnancy tests are based on the level of hCG. Blood pregnancy tests made in medical laboratories also indicate the concentration of hCG. High level of hCG indicates a positive pregnancy. You need to know all reasons for false pregnancy tests.

Sometimes the increased hCG level can be detected in the blood as early as 8 days after conception, but in most cases it can be usually detected around 11 days.

During pregnancy development the hCG levels could increase and decrease, with the levels doubling on average every 30-31 hours until the hCG peak - usually around the 9th and 10th weeks of healthy pregnancy. The level of hCG then decreases slightly until the 16th week where it remains fairly constant until birth.

Pregnancy hCG Levels

from conception	*from Last Menstrual Period (LMP)*	*mIU/ML or IU/L*
7 days	3 weeks	0 to 5
14 days	28 days	3 to 426
21 days	35 days	18 to 7,340
28 days	42 days	1,080 to 56,500
35 - 42 days	49 - 56 days	7,650 to 229,000
43 - 64 days	57 - 78 days	25,700 to 288,000
57 - 78 days	79 - 100 days	13,300 to 253,000
17 - 24 weeks	2nd trimester	4060 to 65,400
25 weeks to term	3rd trimester	3640 to 117,000
After several days postpartum		< 5

Low hCG Levels Causes

wrong calculations (low hCG level could mean that your conception date was miscalculated);
ectopic pregnancy (low hCG could be the signal for ectopic pregnancy);
miscarriage or miscarriage risk (very often miscarriage is correlating with low level of hCG);
some women have low levels of hCG without any problems in pregnancy development (not often).

High hCG Levels Causes

wrong calculations (high hCG level could mean that your conception date was miscalculated);
multiple pregnancies (twins, triples);
molar pregnancy (when tissue that normally becomes a fetus instead becomes a growth in the uterus – it called a mole).

HCG Role in other situations

*Tumor marker*	The β subunit of human chorionic gonadotropin is secreted also by some cancers including seminoma, choriocarcinoma, germ cell tumors, hydatidiform mole formation, teratoma with elements of choriocarcinoma (this is rare), and islet cell tumor. For this reason a positive result in males can be a test for testicular cancer. The normal range for men is between 0-5 IU/ml.
*Fertility*	Human chorionic gonadotropin is extensively used in fertility stimulation. It is very common method for ovulation induction in women with anovulation. In the presence of one or more mature ovarian follicles, ovulation can be triggered by the administration of hCG. HCG is also used in IVF clinics. Patients that undergo IVF, in general, receive hCG to trigger the ovulation process, but have their eggs retrieved at about 36 hours after injection, a few hours before the eggs actually would be released from the ovary. As hCG supports the corpus luteum, administration of hCG is used in certain circumstances to enhance the production of progesterone. Pregnancies who have occurred after a treatment with this medicine are submitted to a higher risk of multiplets. Women who have been treated with hCG are usually more prone to pregnancy losses.
*Male health*	Sometimes males also need hCG - hCG injections are used to stimulate the leydig cells to synthesize testosterone. The intratesticular testosterone is necessary for spermatogenesis from the sertoli cells. Typical uses for hCG in men include hypogonadism and fertility treatment.
*Weight loss*	hCG is triggering the hypothalamus to mobilize stored fat into the bloodstream to be used as "food". It is believed to reset your metabolism and to protect your body's good fat and keep muscle tissue from breaking down (which occurs in other low calorie diets without the use of hCG). In theory, the hCG hormone is supposed to suppress hunger and trigger your body’s use of fat for fuel. Most hCG diet plans restrict dieters to only 500 calories per day of mostly organic, unprocessed foods along with the hCG injections or serum drops under the tongue. Some scientists noted absence of hCG effect on weight loss.
*HIV*	During first few months of pregnancy, the transmission of *HIV*-1 from woman to fetus is extremely rare. It has been suggested that this is due to the high concentration of hCG, and that the beta-subunit of this protein is active against HIV-1.

Contraindications for hCG use

cardiac failure and hypertension;
renal dysfunction;
migraine or epilepsy;
hCG should be used with extreme cautious in the case of prepubertal teenagers in order to reduce the risk of experiencing precocious sexual development or premature epiphyseal closure;
hypersensitivity to hCG medicine;
known or possible androgen-dependent tumors for example male breast carcinoma or prostatic carcinoma

Home pregnancy tests are based on a very simple principle. They work by through the detection of the hormone Human Chorionic Gonadotropin (hCG) in a woman’s urine. This hormone is a hormone secreted by the developing placenta shortly after a fertilized egg has been implanted in the uterine lining.

If a woman is pregnant, the amount of Human Chorionic Gonadotropin (hCG) in her system should be around 25 mIU at 10 dpo (days past ovulation), 50 mIU at 12 dpo, 100 mIU at around two weeks dpo. Because of their high sensitivity factor ( 20 mIU/ml hCG ) in detecting human hCG, both the AimStrip pregnancy tests can confirm pregnancy as early as 6-8 days past ovulation though most women find that the test reports a positive at 9 or 10 days past ovulation.