-hCG (Quantitative)- -hCG
- hCG (Quantitative)
- Human chorionic gonadotrophin (Quantitative, Serum)
- Pregnancy test (Quantitative, Serum)
- Quantitative -hCG
- Serum pregnancy test
- Red top, tiger top, green top, or marbled top tube.
- 5 mL of venous blood
The quantitative ß-hCG test quantifies the serum level of the beta subunit of human chorionic gonadotropin.
Human chorionic gonadotropin (hCG) is a glycoprotein hormone, produced initially by the corpus luteum, and then by the developing placenta, during pregnancy.
This hormone may also be aberrantly produced in men and non-pregnant women by certain neoplasms and acts as a serum tumor marker in these cases.
The test is done to:
- Determine whether a woman is pregnant
- Detect and monitor therapy in molar pregnancy
- Detect and monitor therapy in cases of:
- Cancers of the ovaries
- Cancers of the testicles
- Nongonadal hCG producing tumors
- Evaluation of ectopic pregnancy
- Evaluation of miscarriage (threatened or spontaneous abortion)
Clinical interpretation:
The most common clinical use of the quantitative -hCG test is to monitor expected changes, over time, in -hCG, in patients with vaginal bleeding or pain during early pregnancy.
- In early (4-6 weeks gestational age) normally developing pregnancies, the -hCG rises 67-100% every 72 hours
- A normal rise is reassuring that the pregnancy is developing normally
- A slower than expected rise or decline can be consistent with ectopic pregnancy
- A rapid decline is most consistent with miscarriage; but can happen with ectopic pregnancy
An additional clinical use in early pregnancy is determination of when the developing pregnancy should be visible on ultrasound. This varies institution to institution, but typically, at a value between 1200-2000 IU/L an intrauterine gestational sac should be visible. The absence of an intrauterine gestational sac when one is expected to be present raises concerns about ectopic pregnancy.
Additional information:
- Serum -hCG is a more sensitive test than urine hCG test (it will detect pregnancy earlier)
- Elevations in serum -hCG can be detected before the first missed period, and as early as six days after implantation.
- Levels of -hCG increase steadily during the first 14-16 weeks of gestation and then gradually decrease. It cannot be detected in the blood shortly after a normal delivery.
- Serum -hCG levels are also determined as part of the triple or quadruple screening tests for Down's syndrome. The triple screen measures alpha-fetoprotein (AFP), beta human chorionic gonadotropin (-hCG), and unconjugated estriol (uE3). The quadruple screen measures all these substances and the hormone inhibin-A.
- Low levels of AFP and estriol, along with high levels of hCG suggest an increased risk of fetal chromosomal anomaly such as Downs syndrome.
- Serum -hCG should be undetectable between 10-30 days following an abortion and should consistently fall between serial measurements to the non-pregnant range. If the -hCG does not fall as expected, this indicates presence of -hCG producing tissue that may require removal.
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
Males/non-pregnant women: <5 IU/L (<5 mIU/mL)
During pregnancy, the normal value depends upon the period of gestation. Please note that being 3 weeks pregnant is just 1 week post conception.
| Conv. units (mIU/mL) | SI units (IU/L) | |
|---|---|---|
| 3 wks | 5-50 | 5-50 |
| 4 wks | 40-900 | 40-900 |
| 5 wks | 90-5,000 | 90-5,000 |
| 6 wks | 1,000-56,000 | 1,000-56,000 |
| 7-8 wks | 7,500-225,000 | 7,500-225,000 |
| 9-12 wks | 30,000-180,000 | 30,000-180,000 |
| 13-16 wks | 7,500-270,000 | 7,500-270,000 |
| 17-24 wks | 4,000-150,000 | 4,000-150,000 |
| >24 wks | 4,000-50,000 | 4,000-50,000 |
An elevated serum -hCG level is seen in the following conditions:
- Normal pregnancy
- Ectopic pregnancy (lower than normal pregnancy for corresponding gestational age)
- Non-viable pregnancy and abortion (lower than normal pregnancy for corresponding gestational age)
- Gestational trophoblastic disorders
- Hydatidiform mole
- Invasive mole
- Choriocarcinoma
- Gonadal neoplasms with syncytiotrophoblastic giant cells
- Ovarian adenocarcinoma
- Seminomas
- Teratoma of the testicle
- Nontrophoblastic tumors
- Some gastric carcinomas
- Some hepatomas
- Some pancreatic carcinomas
- Spermatic cord leiomyosarcoma
- Renal cell carcinoma
- Large cell carcinoma of the lung
- Chromosomal abnormalities
- Down's syndrome
A -hCG, in a pregnant woman, higher than expected for estimated gestational age, may be seen in the following conditions:
- Multiple gestation (twins, etc)
- Polyhydramnios
- Hyperemesis gravidarum
- Eclampsia
- Erythroblastosis fetalis
- Gestational trophoblastic disease
- Miscalculation of the date of LMP (last menstrual period)
Drugs that may increase -hCG include:
- Anticonvulsants
- Antiparkinsonian drugs
- Antipsychotics
- Phenothiazines
- Promethazine
- Occurs when the patient is not pregnant
- A -hCG, in a pregnant woman, lower than expected for estimated gestational age, may be seen in the following conditions:
- Ectopic pregnancy
- Non-viable pregnancy
- Incomplete abortion
- Spontaneous abortion
- Threatened abortion
Drugs that may increase -hCG include:
- Diuretics
- Promethazine
- Barisat Z et al. Serum beta human chorionic gonadotropin levels and preeclampsia. Saudi Med J. 2006 Jul;27(7):1001-4.
- Cole LA et al. Gestational trophoblastic diseases: 3. Human chorionic gonadotropin-free beta-subunit, a reliable marker of placental site trophoblastic tumors. Gynecol Oncol. 2006 Aug;102(2):160-4. Epub 2006 May 2
- Condous G et al. Failing pregnancies of unknown location: a prospective evaluation of the human chorionic gonadotrophin ratio. BJOG. 2006 May;113(5):521-7.
- Fukuda M et al. Large Cell Carcinoma of the Lung Secreting Human Chorionic Gonadotropin which Responded to Combination Chemotherapy: Case Report. Japanese Journal of Clinical Oncology. 1990;20:299-305
- Goshen R et al. High Levels of Maternal Serum Human Chorionic Gonadotropin in Down Syndrome Pregnancies: The Possible Role of a Transcription Factor on Chromosome 21. Fetal Diagn Ther. 1999;14:106-111.
- Hotakainen K et al. The free beta -subunit of human chorionic gonadotropin as a prognostic factor in renal cell carcinoma. Br J Cancer. 2002;86:185-189
- Lab Tests Online®. hCG: Common Questions.[Homepage on the Internet]©2001-2006. Last reviewed on June 24, 2004. Last accessed on August 10, 2006. Available at URL: http://www.labtestsonline.org/understanding/analytes/hcg/faq.html
- Laboratory Corporation of America® Human Chorionic Gonadotropin (hCG), Beta Subunit, Quantitative, Serum. [Homepage on the Internet] ©2003. Last updated on November 9, 2004. Last accessed on August 10, 2006. Available at URL: http://www.labcorp.com/datasets/labcorp/html/chapter/mono/ri020200.htm
- MedlinePlus® Medical Encyclopedia. HCG in blood serum – quantitative. [Homepage on the Internet].© 2005. Last updated on November 30, 2004. Last accessed on August 10, 2006. Available at URL: http://www.nlm.nih.gov/medlineplus/ency/article/003510.htm
- Ou SM et al. Production of -hCG by spermatic cord leiomyosarcoma: A paraneoplastic syndrome? J Androl. 2006 Jun 2; [Epub ahead of print]
- Wright D et al. Three-stage contingent screening for Down syndrome. Prenat Diagn. 2006 Jun;26(60:528-34