Testosterooni

Testosterooni, also known as testosterone, is the primary male sex hormone and a key androgen. In humans, most of it is produced by Leydig cells in the testes; smaller amounts are produced by the adrenal glands, and females contribute a small amount from the ovaries.

In fetal development, testosterone guides the formation of male reproductive organs; at puberty it drives secondary sexual characteristics such as facial and body hair, voice deepening, and increased muscle mass. Beyond reproduction, it helps regulate bone density, fat distribution, red blood cell production, mood, and energy levels.

Biologically, testosterone is synthesized from cholesterol through steroidogenesis. It exerts its effects by binding the androgen receptor, altering gene expression. It can be converted to dihydrotestosterone (DHT) by 5-alpha-reductase and to estradiol by aromatase.

Clinically, testosterone is used in hormone replacement therapy for hypogonadism and certain other conditions. Available forms include injections, topical gels or patches, and subcutaneous pellets.

Levels normally peak in late adolescence and decline with age; there is diurnal variation and substantial individual differences.

Excess or deficient levels can cause health issues. Potential risks of improper use include acne, sleep apnea, polycythemia, prostate enlargement, reduced fertility, and mood changes.

Notes: use should be overseen by a clinician, particularly when used for therapy or performance enhancement.