(1,2,6,7-3H)-Testosterone is a radiolabeled form of the corresponding steroid hormone. It can be used to study testosterone metabolism and androgen receptor binding in tissues.

Epitestosterone (17alpha-hydroxy-4-androsten-3-one) is a naturally occurring epimer of testosterone. It apparently parallels the formation of testosterone, but on the other hand its concentration is not influenced by exogenous administration of testosterone. This fact creates the basis of the present doping control of testosterone abuse. Epitestosterone can be considered as a weak antiandrogen in the term of displacement of androgen from receptor binding and as an efficient inhibitor of 5 alpha-reductase. Epitestosterone exerts androgen receptor-independent neuroprotective activity in vitro.

Testosterone acetate, a testosterone ester, is an androgen. It is a steroid lipid molecule considered to be practically insoluble (in water) and basic. It is an anabolic steroid and testosterone prodrug. Testosterone acetate has a faster rate of absorption in the body then other esters. In combination with two other testosterone esters, testosterone valerate and testosterone undecanoate, it is a part of Deposterona, an injectable veterinary blend steroid preparation marketed in Mexico. With its blend of slow and fast-acting esters, Deposterona is essentially a low dosed alternative to Sustanon and is used primarily to treat impotence, weakness, fatigue, and hypogonadism in male breeding animals (cows, pigs, canines, and sheep), and also as a general protein-sparing anabolic. Testosterone acetate is classified as a Schedule III drug by the United States Drug Enforcement Agency and is only legal with a prescription due to his potential for misuse and abuse.

Testosterone 3-(O-carboxymethyl)oxime is a structural testosterone derivative, oxime O-ether formed from testosterone and (aminooxy)acetic acid. It was prepared for use in the anabolic steroids detection tests in human. It has been used for the hormonal analysis of sexual dimorphism in the electric fish Apteronotus and also for developing environmental biosensors for the detection of testosterone in water samples.

Estradiol an aromatized C18 steroid with hydroxyl group at 3-beta- and 17-beta-position. Estradiol-17-beta is the most potent form of mammalian estrogenic steroids. In humans, it is produced primarily by the cyclic ovaries and the placenta. It is also produced by the adipose tissue of men and postmenopausal women. The 17-alpha-isomer of estradiol binds weakly to estrogen receptors (receptors, estrogen) and exhibits little estrogenic activity in estrogen-responsive tissues. Estradiol enters target cells freely (e.g., female organs, breasts, hypothalamus, pituitary) and interacts with a target cell receptor. When the estrogen receptor has bound its ligand it can enter the nucleus of the target cell, and regulate gene transcription which leads to formation of messenger RNA. The mRNA interacts with ribosomes to produce specific proteins that express the effect of estradiol upon the target cell. Estradiol is used for the treatment of urogenital symptoms associated with post-menopausal atrophy of the vagina (such as dryness, burning, pruritus and dyspareunia) and/or the lower urinary tract (urinary urgency and dysuria). Estradiol is marketed under the brand name Climara (among others), indicated for: the treatment of moderate to severe vasomotor symptoms due to menopause, treatment of symptoms of vulvar and vaginal atrophy due to menopause, treatment of hypoestrogenism due to hypogonadism, castration or primary ovarian failure and prevention of postmenopausal osteoporosis.

Testosterone is a steroid sex hormone found in both men and women. In men, testosterone is produced primarily by the Leydig (interstitial) cells of the testes when stimulated by luteinizing hormone (LH). It functions to stimulate spermatogenesis, promote physical and functional maturation of spermatozoa, maintain accessory organs of the male reproductive tract, support development of secondary sexual characteristics, stimulate growth and metabolism throughout the body and influence brain development by stimulating sexual behaviors and sexual drive. In women, testosterone is produced by the ovaries (25%), adrenals (25%) and via peripheral conversion from androstenedione (50%). Testerone in women functions to maintain libido and general wellbeing. Testosterone exerts a negative feedback mechanism on pituitary release of LH and follicle-stimulating hormone (FSH). Testosterone may be further converted to dihydrotestosterone or estradiol depending on the tissue. The effects of testosterone in humans and other vertebrates occur by way of two main mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of certain estrogen receptors. Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (DHT) by the cytoplasmic enzyme 5α-reductase. DHT binds to the same androgen receptor even more strongly than T, so that its androgenic potency is about 2.5 times that of T. The T-receptor or DHT-receptor complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to specific nucleotide sequences of the chromosomal DNA. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects. Testosterone is used as hormone replacement or substitution of diminished or absent endogenous testosterone. Use in males: For management of congenital or acquired hypogonadism, hypogonadism associated with HIV infection, and male climacteric (andopause). Use in females: For palliative treatment of androgen-responsive, advanced, inoperable, metastatis (skeletal) carcinoma of the breast in women who are 1-5 years postmenopausal; testosterone esters may be used in combination with estrogens in the management of moderate to severe vasomotor symptoms associated with menopause in women who do not respond to adequately to estrogen therapy alone.