About Testosterone
Testosterone is the primary androgenic hormone produced in the testes (men) and ovaries and adrenal glands (women), playing a fundamental role in energy, libido, muscle mass, bone density, mood, and cognitive function in both sexes. Low testosterone in men — increasingly common even in younger adults — manifests as fatigue, low sex drive, reduced muscle mass, increased body fat, and depression. Testing total testosterone is the standard first step, but free testosterone (the biologically active, unbound fraction) often tells a more complete story.