Testosterone

Function

Testosterone is the primary androgenic steroid hormone. In males, it is mainly produced in the testes (Leydig cells), while in females, it is produced in the ovaries and adrenal glands. It is responsible for the development of secondary sexual characteristics, bone density, muscle mass, and libido. It also plays a vital role in mood regulation and red blood cell production.

Why it is Ordered

In men, it is ordered to investigate symptoms of 'Low T,' such as erectile dysfunction, fatigue, infertility, or decreased muscle mass. In women, it is frequently used to investigate signs of virilization or hormonal imbalance, such as hirsutism (excess hair growth), acne, or irregular menstrual cycles.

Associated Conditions

• Hypogonadism (Male): Primary (testicular failure) or secondary (pituitary/hypothalamic issues).
• Polycystic Ovary Syndrome (PCOS): A common cause of elevated testosterone in females.
• Adrenal Hyperplasia: Can cause excess androgen production.
• Pituitary Tumors: Can disrupt the signals (LH/FSH) that tell the body to produce testosterone.
• Anabolic Steroid Use: Can cause artificially high levels (if current use) or extremely low levels (post-cycle suppression).

Interpretation Nuance

Total testosterone measures both free testosterone and testosterone bound to proteins (SHBG and albumin). Changes in protein levels can affect the 'Total' count without affecting the bioactive 'Free' portion.