What is Testosterone?
Testosterone is the principal androgen synthesised by Leydig cells of the testes in males and in smaller amounts by the ovaries and adrenal cortex in females. Circulating testosterone exists in three fractions: tightly bound to sex hormone-binding globulin (approximately 60%), loosely bound to albumin (approximately 38%), and free (1–2%). Liquid chromatography–tandem mass spectrometry measures total testosterone with superior specificity and sensitivity at low concentrations compared with immunoassay, making it the gold standard for females, children, and hypogonadal males.