What is Testosterone Total?
Testosterone Total is done to detect the levels of testosterone in males and females. In males, it is done to diagnose the cause of conditions like erectile dysfunction or infertility. In females, it is done to diagnose the cause of conditions like virilization (females develop masculine physical features). Also, in females, it is done to diagnose the cause of infertility or polycystic ovary syndrome (PCOS). In children, it is done to find out the reason for ambiguous genitalia (a condition in which the infant's genitals are not clearly of male or female) and for delayed or early puberty.
Why is Testosterone Total done?
Masculine physical features
Excessive body hair
Abnormal uterine bleeding
What does Testosterone Total Measure?
Testosterone is a sex hormone which is mainly found in men. It can also be found in women but in small amounts. The appearance of male physical characteristics is due to testosterone hormone. Testosterone Total measures the levels of testosterone in the blood.
In men, testosterone is produced by the Leydig cells present in the testicles. It is also produced by the adrenal glands in both males and females. In females, small amounts of testosterone are produced by the ovaries.
The function of testosterone is to develop secondary sex characteristics which include enlargement of the penis, body hair growth, development of muscle, and deepening of the voice. During puberty, it is produced in large amounts in males. In adult males, its function is to regulate the sex drive and to maintain muscle mass. In adult females, the testosterone gets converted to estradiol, which is the main sex hormone in females.
The testosterone hormone production is regulated by luteinizing hormone (LH), which is produced by the pituitary gland. As the levels of testosterone rise, the production of LH decreases which in turn slows down the production of testosterone. Similarly, when the levels of testosterone fall, it leads to an increase in production of LH which stimulates testosterone production.
The levels of testosterone are highest in the early morning and lowest in the evening. With exercise, the levels of testosterone increase and with age the levels decrease.
In the blood, about two-thirds of testosterone hormone is bound to sex-hormone binding globulin (SHBG) and about one-third is bound to albumin. A small amount is present as free testosterone.
Interpreting Testosterone Total results
In adult men:
19 - 49 years: 249-836 ng/dL
50 years and older: 193-740 ng/dL
In adult women:
19 - 49 years: 8-48 ng/dL
50 years and older: 2-41 ng/dL
Reference range may vary from lab to lab