Initially, the hormone that exists in the serum may be bound to a protein that allows it to be transported in the body. This protein is called sex hormone binding globulin (SHBG). The total testosterone consists of two forms of testosterone; one is bound to SHBG and the other is free circulating testosterone unattached to serum proteins. In conditions such as hypothyroidism and cirrhosis, measurement of the total testosterone level may be normal but the patient may have symptoms of low testosterone. In these conditions, the SHBG is increased and this decreases the amount of testosterone that is available for use. The opposite is true where SHBG is decreased and the free testosterone levels are high. This situation is seen in men with obesity and hypothyroidism. These men have normal amounts of testosterone available for use by the body but the serum testosterone level is decreased. Saliva or urine test results are considered a good representation of free hormone levels.
Because steroid hormone binding globulin (SHBG) is known to be decreased in hypothyroidism, obesity and acromegaly, and increased in hyperthyroidism and estrogen therapy, it is necessary to measure the free biologically active testosterone in these conditions, when total testosterone can be misleading. If testosterone is low, a full hormonal evaluation consisting of LH, prolactin, FSH, and TSH may be recommended.
Once it has been determined that the testosterone level is low, measuring the luteinizing hormone (LH) can help determine the cause. This separates the patients who have testicular disease from those who have diseases of the pituitary gland, the master gland that sits at the base of the brain and essentially controls many bodily functions. A low testosterone level may indicate an elevated prolactin level as well, a condition known as a hyperprolactinoma. Elevated prolactin can decrease testosterone levels by decreasing the secretion of the hormone that tells the testicle to produce testosterone.
Average levels of blood testosterone for males should range between 300-1,000ng/dl, which is too wide of a spectrum when considering athletes. Athletes who need strength should have 800ng/dl or higher to optimize strength gains, hasten recovery and to have the aggressive drive to compete. Unfortunately, the average drug-free athlete is probably somewhere around 500ng/dl, which is too low.
Test Testosterone Levels can help with the following
Key
| Highly recommended |
Glossary
Testosterone
The principal male sex hormone that induces and maintains the changes that take place in males at puberty. In men, the testicles continue to produce testosterone throughout life, though there is some decline with age. A naturally occurring androgenic hormone.
Serum
The cell-free fluid of the bloodstream. It appears in a test tube after the blood clots and is often used in expressions relating to the levels of certain compounds in the blood stream.
Hormones
Chemical substances secreted by a variety of body organs that are carried by the bloodstream and usually influence cells some distance from the source of production. Hormones signal certain enzymes to perform their functions and, in this way, regulate such body functions as blood sugar levels, insulin levels, the menstrual cycle, and growth. These can be prescription, over-the-counter, synthetic or natural agents. Examples include adrenal hormones such as corticosteroids and aldosterone; glucagon, growth hormone, insulin, testosterone, estrogens, progestins, progesterone, DHEA, melatonin, and thyroid hormones such as thyroxine and calcitonin.
Protein
Compounds composed of hydrogen, oxygen, and nitrogen present in the body and in foods that form complex combinations of amino acids. Protein is essential for life and is used for growth and repair. Foods that supply the body with protein include animal products, grains, legumes, and vegetables. Proteins from animal sources contain the essential amino acids. Proteins are changed to amino acids in the body.
Hypothyroidism
Diminished production of thyroid hormone, leading to low metabolic rate, tendency to gain weight, and sleepiness.
Cirrhosis
A long-term disease in which the liver becomes covered with fiber-like tissue. This causes the liver tissue to break down and become filled with fat. All functions of the liver then decrease, including the production of glucose, processing drugs and alcohol, and vitamin absorption. Stomach and bowel function, and the making of hormones are also affected.
Steroid
Any of a large number of hormonal substances with a similar basic chemical structure containing a 17-carbon 14-ring system and including the sterols and various hormones and glycosides.
Hyperthyroidism
An abnormal condition of the thyroid gland resulting in excessive secretion of thyroid hormones characterized by an increased metabolism and weight loss.
Estrogen
One of the female sex hormones produced by the ovaries.
Prolactin
An anterior pituitary peptide hormone that initiates and maintains lactation.
Luteinizing Hormone
Anterior pituitary hormone stimulating estrogen production by the ovary; promoting formation of progesterone by the corpus luteum in women and stimulating testosterone release in men.
Pituitary
The pituitary gland is small and bean-shaped, located below the brain in the skull base very near the hypothalamus. Weighing less than one gram, the pituitary gland is often called the "master gland" since it controls the secretion of hormones by other endocrine glands.
ng
Nanogram: 0.000000001 or a billionth of a gram.