What are the other Names for this Test? (Equivalent Terms)
- Bioavailable Testosterone Blood Test
- Free Testosterone Blood Test
- Total Testosterone Blood Test
What is Testosterone Blood Test? (Background Information)
- Testosterone is a major male sex hormone or androgen. It is responsible for the development of the male sex organs and the maturation of sperm. It also causes the development of secondary sex characteristics such as male distribution of hair and deepening of the voice that occurs during puberty
- Men produce testosterone in large amounts during puberty. Leydig cells or interstitial cells in the testes produce most of the testosterone hormone. Leydig cells are stimulated by luteinizing hormone (LH) made by the pituitary gland
- Some testosterone is also produced by the adrenal glands, which sits atop the kidneys, in both men and women
- Women produce testosterone in small quantities. Aside from the adrenal glands, the ovaries produce minor amounts of testosterone. In women, testosterone is largely used to make estradiol, the main female sex hormone
- Secretion of testosterone is controlled through a negative feedback mechanism. LH stimulates testosterone production, and increased testosterone inhibits LH release. This ensures balanced testosterone levels in the body
- Most testosterone molecules circulate in a protein-bound form in blood, i.e. sex-hormone-binding globulin (SHBG) and albumin bind testosterone. A small amount of testosterone (about 1-4%) circulates unbound
- Tumors in the testes, ovaries, pituitary gland, and adrenal gland may cause an over-production of testosterone. This may lead to the onset of puberty in males before the age of 10 years. In women, it may cause masculinization and menstrual abnormalities
- Any other health issues with these organs may diminish testosterone production. This can impair the maturation of sperm and the attainment of an erection during intercourse; this may decrease one’s reproductive capacity
- The Testosterone Blood Test is a test to assess the levels of testosterone circulating in blood. It is used to diagnose neuroendocrine cancers and other disorders affecting testosterone production
What are the Clinical Indications for performing the Testosterone Blood Test?
Following are the clinical indications for performing a Testosterone Blood Test:
- Early or late onset of puberty
- Distinguishing between primary and secondary hypogonadism
- Masculinization in females such as excessive hair growth
- Decreased sex drive
- Erectile dysfunction
- Diminished menstrual cycle
- Abnormal uterine bleeding
How is the Specimen Collected for Testosterone Blood Test?
Following is the specimen collection process for Testosterone Blood Test:
Sample required: Blood
Process of obtaining blood sample in adults:
- A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
- The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
- The needle cap is removed and is held in line with the vein, pulling the skin tight
- With a small and quick thrust, the vein is penetrated using the needle
- The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
- The wrap band is removed, gauze is placed on the collection site, and the needle is removed
- The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
- The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal
Preparation required: No special preparation is needed prior to the test.
What is the Significance of the Testosterone Blood Test Result?
The significance of Testosterone Blood Test is explained:
- Increased testosterone levels may indicate:
- Adrenal hyperplasia
- Adrenocortical tumors
- Idiopathic sexual precocity
- Polycystic ovaries
- Syndrome of androgen resistance
- Testicular or extra-gonadal tumors
- Trophoblastic tumors during pregnancy
- Virilizing ovarian tumors
- Use of anabolic steroids
- Adrenal hyperplasia
- Decreased testosterone levels may indicate:
- Delayed puberty
- Down syndrome
- Hepatic insufficiency
- Klinefelter’s syndrome
- Myotonic dystrophy
- Primary and secondary hypogonadism
- Primary and secondary hypopituitarism
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results based on the overall clinical scenario.
Additional and Relevant Useful Information:
- Certain factors interfere with the results of the Testosterone Blood Test. These include strenuous exercise, age, nutrition status, and alcohol consumption
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.
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References and Information Sources used for the Article:
Lab Tests Online (2014, May 5). Retrieved December 1, 2014 from http://labtestsonline.org/understanding/analytes/testosterone/
Martini, F., Nath, J. L., & Bartholomew, E. F. (2012). Fundamentals of anatomy & physiology (9th ed.). San Francisco: Benjamin Cummings.
Schnell, Z. B., Van, L. A., & Kranpitz, T. R. (2003). Davis's Comprehensive handbook of laboratory and diagnostic tests: With nursing implications. Philadelphia: F.A. Davis.