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Testosterone levels can only be confirmed through lab testing. A serum total testosterone (blood test) is usually sufficient and urine or saliva testing will also work.
The hormone that exists in the serum may initially 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.
Reasons For Use
Because SHBG is known to be decreased in cases of 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 (luteinizing hormone), prolactin, FSH and TSH may be recommended.
Once it has been determined that the testosterone level is low, measuring the 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.
Expected Outcome
Average levels of blood testosterone for males should range between 300-1,000ng/dl, which is too wide 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.
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Testosterone Levels, Test can help with the following:
KEY | | Highly recommended |
GLOSSARY
Cirrhosis (Liver 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.
Deciliter (dL)
0.1 or one tenth of a liter.
Estrogen (Oestrogen)
One of the female sex hormones produced by the ovaries.
Gland (Glands)
The glandular system is one of the most important and complicated systems of the body. Gland tissue can be either an organ or general tissue that secretes chemicals and there are two types of gland: exocrine and endocrine. Those glands which secrete chemicals through tubules or ducts are called exocrine and include sweat, tear and salivary glands. Ductless glands - part of the endocrine system - secrete special chemicals (hormones) directly into the blood.
Hormones (Hormone)
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.
Hyperthyroidism (Hyperthyroid)
An abnormal condition of the thyroid gland resulting in excessive secretion of thyroid hormones characterized by an increased metabolism and weight loss.
Hypothyroidism (Hypothyroid)
Diminished production of thyroid hormone, leading to low metabolic rate, tendency to gain weight, and sleepiness.
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.
mol (mmol, nmol, pmol, umol)
Mole. The amount of a substance that contains as many atoms, molecules, ions, or other elementary units as the number of atoms in 0.012 kilograms of carbon 12. The number is 6.0225 × 10^23, or Avogadro's number. Also called gram molecule.
mmol: millimole: 0.001 or one thousandth of a mole.
umol: micromole: 0.000001 or one millionth of a mole.
nmol: nanomole: 0.000000001 or one billionth of a mole.
pmol: picomole: 0.000000000001 or one trillionth of a mole.
Nanogram (ng)
0.000000001 or a billionth of a gram.
Pituitary (Pituitary Gland)
The pituitary gland is a small (half-inch), bean-shaped organ that hangs down from the lower center of the brain on a stalk attached to another gland, 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. It regulates many body activities, and is partitioned into front and back lobes. The front lobe is stimulated by the hypothalamus, and produces any one of six different hormones that in turn stimulate the thyroid, adrenal and reproductive glands, and also breast milk production.
Prolactin
An anterior pituitary peptide hormone that initiates and maintains lactation.
Protein (Proteins)
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.
Saliva (Salivary)
The watery mixture of secretions from the salivary and oral mucous glands that lubricates chewed food and moistens the oral walls.
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.
SHBG (Sex Hormone Binding Globulin, Sex Hormone-Binding Globulin)
A glycoprotein, synthesized in the liver, which binds testosterone and 5 alpha-dihydrotestosterone strongly, and estradiol somewhat less strongly. Circulating testosterone is mainly bound to protein - primarily SHBG, but also to albumin and cortisol-binding globulin. Since variations in the carrier protein levels may affect the concentration of testosterone in circulation, SHBG levels are commonly measured as a supplement to total testosterone determinations. The "free androgen index" (FAI), calculated as the ratio of total testosterone to SHBG, has proved to be a useful indicator of abnormal androgen status in conditions such as hirsutism.
Testicles (Testicle, Testicular)
Egg-shaped sex glands in the scrotum that secrete male hormones such as testosterone, and produce sperm.
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.
Last updated: Apr 13, 2008
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