Testosterone

Testosterone is a hormone made mainly in the testes in men and in smaller amounts in the ovaries and adrenal glands in women. It plays important roles in sexual development, muscle and bone strength, energy levels, and mood. Levels that are too high or too low can cause a variety of symptoms and may signal an underlying health condition. A blood test can measure your testosterone level, and your doctor will interpret the result alongside your symptoms and other test findings. It is important not to interpret this result in isolation, as many factors can influence testosterone levels.

When elevated: Elevated testosterone in males may suggest exogenous androgen use, androgen-secreting tumors, or congenital adrenal hyperplasia. In females, elevated testosterone is associated with polycystic ovary syndrome (PCOS), adrenal or ovarian androgen-secreting tumors, and congenital adrenal hyperplasia, and may manifest as hirsutism, acne, menstrual irregularity, and virilization. When low: Low testosterone in males (hypogonadism) is associated with decreased libido, erectile dysfunction, fatigue, reduced muscle mass, increased adiposity, osteoporosis, mood disturbances, and impaired fertility. In females, low testosterone may contribute to reduced libido, fatigue, and decreased bone density, though clinical thresholds are less well established.

Testosterone supports muscle protein synthesis, strength gains, bone density, and recovery—key factors in training adaptation and performance. Athletes may track testosterone to monitor training stress, recovery adequacy, and potential overtraining; however, single measurements have limited predictive value without trend data and clinical correlation.