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What is a beta hCG test?

Human chorionic gonadotropin (hCG) is a proteinaceous hormone produced by the body of a woman after she conceives. It helps to maintain pregnancy until the development of placenta and is mainly secreted in the first trimester. The levels of hCG in blood increase from the 8th day after conceiving and peak during the 10th week. hCG test is, therefore, used in simple home pregnancy kits that indicate conception by a colour change of a band in the test kit. 

Beta hCG (β-hCG) is a subunit of hCG which can be present in its free form in the serum (the liquid portion of blood). Most laboratories check β-hCG values when the doctor orders an hCG test. Furthermore, the levels of this hormone have been found to be elevated in certain kinds of cancers; therefore, it is also used as a tumour marker. 

β-hCG levels in blood are actively being researched as a tool for managing problems associated with in-vitro fertilisation.

  1. Why is beta hCG test performed?
  2. How do you prepare for beta hCG test?
  3. How is beta hCG test performed?
  4. Beta hCG test results and normal values/range

β-hCG test may be ordered in the following cases:

  • To confirm a pregnancy
  • As part of a Down syndrome test for all pregnant woman at 12-13 weeks
  • Gynaecomastia (enlargement of breast tissue in men)
  • Early onset of puberty in children
  • Before an obstetric imaging process
  • To confirm the diagnosis of suspected cancers
  • To diagnose the cause of non-viable pregnancies in the past
  • As a part of cancer treatment

hCG test is also useful in detecting chromosomal abnormalities in foetus and assessing the growth and size of tumours.

No special preparations are needed for this test. It is always best to inform the doctor about any medicines or herbs that you are taking. Do not change the course of any medicines without the consent of the doctor. Also, let the doctor know about any previous medical conditions along with a detailed history of past pregnancies and reproductive health.

beta hCG test is essentially a blood test, for which, the sample is collected from a vein in the arm of the patient, at any time of the day.

During the process, a laboratory technician will tie a tourniquet around your arm to help locate a vein. He/ she will then clean the area on the arm and using a sterile needle, withdraw some amount of blood from a vein. This may cause a little discomfort, though it will disappear soon.

The blood sample will be deposited in a sterile vial and sent for testing. The technician will put a bandage or cotton gauze at the site of puncture to stop blood flow.

Some individuals may experience a mild bruise at the site of needle insertion, but it will fade away in a few hours.

Normal results:

Normal results would determine whether a woman is pregnant or not. Absence of β-hCG in blood indicates that the woman is not pregnant; presence of β-hCG indicates a possible pregnancy. In pregnant women, hCG rises steadily as the pregnancy proceeds, from above (25 U/L a value that indicates pregnancy) to 750 U/L within the first 4 weeks. Around the 13th week, the values of hCG can go up to 9,000-210,000 U/L. Here is a table depicting the changing values of beta HCG during pregnancy:

Weeks from last menstrual period  Normal hCG levels (mIU/mL)
4 0-750
5 200-7,000
6 200-32,000
7 3,000-160,000
8-12 32,000-210,000
13-16 9,000-210,000
16-29 1,400-53,000
29-41 940-60,000

In men or prepubescent children, no hCG in blood indicates normal results.

Abnormal results:

In pregnant women:

If hCG levels do not follow the normal patterns during pregnancy, it could indicate an underlying condition like:

  • Ectopic pregnancy
  • Gestational trophoblastic disease
  • Hydatidiform mole
  • Choriocarcinoma

A higher than normal hCG level around the 16th week of pregnancy can indicate the presence of Down’s syndrome in the foetus.

Presence of hCG in a non-pregnant individual could be indicative of:

  • Testicular or ovarian tumour
  • Germline tumours in the brain
  • Hepatoblastoma
  • Liver cirrhosis
  • Stomach ulcers
  • Skin, stomach, lung, pancreatic or breast cancer

hCG test is not a diagnostic test for cancer; instead, it prompts the doctor to order more tests and identify the underlying condition if necessary. The doctor correlates the level of hCG in a particular disorder after processing results from other tests.

False-positive results may show up in post-menopausal women or marijuana smokers.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.

References

  1. Marshal W.J, Lapsley M, Day A.P, Ayling R.M. Clinical biochemistry: Metabolic and clinical aspects. 3rd ed. Churchill Livingstone: Elsevier; 2014. Chapter 22, Reproductive function in the female; p.436-437.
  2. Gerard J. Tortora, Bryan Derrickson. Principles of anatomy and physiology. 14th ed. Wiley Publication; 2014. Chapter 29, Development and Inheritance; p.1110.
  3. Canadian Cancer Society [internet]. Human chorionic gonadotropin (hCG or b-hCG)
  4. Marshal W.J, Lapsley M, Day A.P, Ayling R.M. Clinical biochemistry: Metabolic and clinical aspects. 3rd ed. Churchill Livingstone: Elsevier; 2014. Chapter 42, Tumour Markers; p. 831-843.
  5. Surampudi K, Gundabattula SR. The Role of Serum Beta hCG in Early Diagnosis and Management Strategy of Ectopic Pregnancy. J Clin Diagn Res. 2016;10(7): p.QC08–QC10.
  6. Naredi N, Singh SK, Sharma R. Does first serum beta-human chorionic gonadotropin value prognosticate the early pregnancy outcome in an in-vitro fertilisation cycle? Journal of Human Reproductive Sciences. 2017; 10(2): p.108-113.
  7. Provan D, Oxford Handbook of Clinical and Laboratory Investigation. 4th ed. United Kingdom: Oxford University Press; 2018. Chapter 13, Radiology; p.820.
  8. Riley RS, McPherson RA. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. Philadelphia, PA: Elsevier; 2017. Chap 23, Reproductive function and pregnancy; p. 411.
  9. Benioff Children's Hospital [internet]: University of California, San Francisco; HCG in Blood Serum — Qualitative
  10. Health direct [internet]: Department of Health: Australian government; hCG levels
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