Total testosterone measures the combined amount of testosterone in the blood, both protein-bound and free. It is the most common starting point for evaluating androgen status in both men and women.
What it measures. The combined concentration of testosterone bound to sex hormone-binding globulin (SHBG) and albumin, plus the small free fraction. Most circulating testosterone is bound and not biologically active at any given moment.
Why it matters. Low total testosterone in men is associated with reduced muscle mass, low libido, fatigue, depressed mood, and unfavorable body composition. In women, levels that drift too high or too low can affect cycles, libido, and metabolic health. Levels naturally decline with age.
What influences it. Sleep quality, body composition, resistance training, chronic stress, alcohol, certain medications, environmental exposures, time of day, and underlying gonadal or pituitary function.
Worth knowing. Total testosterone alone can mislead, particularly when SHBG is high or low — a normal total can mask a low free testosterone. From a functional medicine perspective, total testosterone is read alongside free testosterone, SHBG, LH, and estradiol, and morning draws are essential because levels peak early in the day.
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