Natural testosterone is a term used to describe the hormone testosterone that is naturally produced by the testes and ovaries of humans and animals. Testosterone, or rather the effects of testosterone, has long been recognized as exerting a significant effect on the human body.
Testosterone is classified as an androgen. Androgens are a group of hormones that control masculine sex characteristics. They play a role in maintenance of systemic anabolic effects, particularly metabolism of salts, fluid balance and bone growth.
Testosterone has significant effects on libido, mood and depression.
Testosterone is crucial for the development and maintenance of the male sex organs and the male secondary sex characteristics. These include muscle bulk, facial and axillary hair, changes in fat distribution and deepened voice.
Testosterone makes the skin more vascular and less fatty.
Common causes for reduced testosterone production that results in a deficiency state includes:
Testicular disorders
Klinefelter's syndrome
Cryptorchidism and defects of testis development (Twisted or strangulated testes)
Orchitis (Inflammation of the testes resulting in permanent damage)
Orchidectomy (surgical removal of the testes)
Toxin exposure (radiation, chemotherapy or radiotherapy, domestic, industrial or environmental poisons)
Brain disorders (Hypothalamic-pituitary dysregulation)
Kallmann's syndrome (a genetic disorder)
Other genetic causes
Pituitary gland tumour and treatment (surgery and/or irradiation)
Haemochromatosis (Blood iron disorder)
Craniopharyngioma (benign tumour of the brain)
External factors
Acute critical illness, burns, major trauma or surgery
Drug use (eg, opiates, glucocorticoids, anabolic steroids)
Chronic disease and its treatment
Alcohol abuse
Smoking