Testosterone, Free, Direct with Total Testosterone, LC/MS-MS

This test measures both total and free testosterone using liquid chromatography–tandem mass spectrometry (LC/MS-MS), which is more accurate than immunoassay methods, particularly at low and high concentrations. Testosterone regulates muscle protein synthesis, bone mineral density, erythropoiesis, libido, and mood in both sexes. Overtraining, caloric deficit, sleep deprivation, and psychological stress are all associated with suppression of the hypothalamic-pituitary-gonadal (HPG) axis and reduced testosterone output. Conversely, resistance training acutely elevates testosterone. Longitudinal tracking provides more useful data than a single timepoint, as testosterone exhibits diurnal variation (peak in early morning) and day-to-day fluctuation.","abnormal_indicates":"Low total or free testosterone is associated with fatigue, reduced lean mass, depressed mood, decreased libido, and impaired bone density. In males, levels below ~300 ng/dL total are generally considered hypogonadal. Elevated testosterone in the absence of exogenous use may suggest androgen-secreting pathology."}

Low total or free testosterone is associated with fatigue, reduced lean mass, depressed mood, decreased libido, and impaired bone density. In males, levels below ~300 ng/dL total are generally considered hypogonadal. Elevated testosterone in the absence of exogenous use may suggest androgen-secreting pathology.

Overtraining, caloric deficit, sleep deprivation, and psychological stress are all associated with suppression of the hypothalamic-pituitary-gonadal (HPG) axis and reduced testosterone output. Conversely, resistance training acutely elevates testosterone. Longitudinal tracking provides more useful data than a single timepoint, as testosterone exhibits diurnal variation (peak in early morning) and day-to-day fluctuation.