Testosterone

Testosterone
Testosterone is an anabolic steroid synthesized primarily by the testes in males, the ovaries in females, and adrenal glands in both sexes. Testosterone is synthesized from androstenedione, a product of dehydroepiandrosterone (DHEA) and progesterone, both of which are products of pregnenolone and cholesterol.

At puberty, and throughout most of the reproductive years, approximately 10-20 times more testosterone is synthesized in males than in females. In males at puberty, the much higher level of testosterone is responsible for the development of male external genitalia and secondary hair patterns, stimulation of spermatogenesis, stimulation of anabolic activity leading to increased muscle mass, and behavioral changes. In pubescent females, testosterone effects are more subtle but equally important for proper musculo-skeletal development, general anabolic activity, and libido. In both sexes, testosterone enhances aerobic metabolism and increases protein synthesis.

Testosterone decreases with age in both men and women. Testosterone replacement has been used to treat some postmenopausal symptoms, especially lack of libido in women who have received chemotherapy. It has also been used effectively in the treatment of anemia and the weakness and muscle wasting syndrome associated with AIDS. Recent research on the effects of testosterone on aging demonstrates a gain in lean body mass and a possible decline in bone loss when used in elderly patients.

Since testosterone can have significant side effects (acne, hirsutism, deepening voice, and clitorimegaly) measurement of levels can help define a deficiency and allow titration of therapy without risking toxicity.

Interpretation of Results
There is significant diurnal variation in testosterone levels in both men and women. It is important to note the time of day clinical samples are collected.

Salivary testosterone represents the unbound serum fraction, therefore levels are lower than serum levels. Patients using transdermal testosterone creams may have very high salivary testosterone levels.

Age and Sex Specific Ranges for Testosterone in Saliva
(Unsupplemented A.M. Ranges in pg/ml)

Female                                                         Male
Age                     Range                              Age                       Range
20 - 29                   17 - 52                           20 - 29                     42 – 145
30 - 39                   15 - 44                           30 - 39                     53 – 114
40 - 49                   13 - 37                           40 - 49                     41 – 104
50 - 59                   12 - 34                           50 - 59                     36 – 96
60 - 69                   12 - 35                           60 - 69                     32 – 86
70 - 79                   11 - 34                           70 - 79                     31 – 81
                                                                         >80                     26 - 54

References
1) Zumoff B, Strain GW, Miller LK, Roser W: 24 hour mean plasma testosterone concentration declines with age in normal premenopausal women, J Clin Endocrinol Metab 1995 April;80(4):1429-30
2) Tennekoon KH, Karunanayake EH: Serum FSH, LH, and testosterone concentrations in fertile men: effect of age, Int J Fertil 1993 March-April;38(2):108-112
3) Rabkin JG, Rabkin R, and Wagner G: Testosterone replacement therapy in HIV illness, Gen Hosp Psychiatry 1995 Jan; 17(1):37-42
4) Dorfman RI, Shipley RA: Androgens, John Wiley and Sons Inc. New York 1959:116-118
5) Dabbs JM, Salivary testosterone measurements: Collecting, storing and mailing saliva samples, Physiology & Behavior 1990;49:815-187
6) Johnson SG, Joplin GF, Burrin JM: Direct Assay for Testosterone in Saliva: Relationship with a Direct Serum Free Testosterone Assay. Clin Chim Acta 1987;163:309-318
7) Dabbs JM: Salivary Testosterone Measurements: Reliability Across Hours, Days, and Weeks. Physiol Behav 1990;48:83-86
8) Dabbs JM, Hargrove MF: Age, Testosterone and Behavior Amone Female Prison Inmates. Psychosom Med 1997;5:477-480