Introduction
Men commonly feel that if their testosteone isn’t “optimized” and high, they are missing out on greater health in a variety of ways. But what can a testosterone result actually tell us? How can results be interpreted with appropriate nuance that is needed? How low is low enough to be problematic?
In situations where a test flags testosterone as low, there is a belief this means automatically starting testosterone replacement therapy. While TRT can be an excellent intervention in appropriate cases, when is it actually likely to benefit someone, and when is it not?
For many people the decision seems straightforward: get a blood test, see whether testosterone is a little low, and start TRT. However, this simplistic thinking is full of potential issues that are important to understand.
Dr. Austin Baraki returns to discuss how testosterone testing should inform treatment decisions, what benefits to expect, and the questions surrounding fertility and long-term safety.
[03:50] Dr Austin Baraki’s work
[06:33] When and why test?
[10:36] Probability and context impacts interpretation
[14:13] What labs measure
[21:15] Specific vs nonspecific symptoms
[28:35] Primary vs secondary hypogonadism
[32:30] Lifestyle vs TRT decisions
[35:21] TRT risks
[39:32] Testing timing and variability
[41:55] Androgen receptor genetics
[44:28] Free vs total testosterone
[48:57] Low-normal results: what now?
[57:45] TRT risks?: heart and prostate
[01:03:55] Side effects and monitoring
Episode Resources
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- McCormack & Holmes, 2020 – Your results may vary: the imprecision of medical measurements
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Guest Information
Austin Baraki, MD is an internal medicine physician with specific expertise medical education, obesity medicine, as well as science & health communication. He is currently an internal medicine physician at Brooke Army Medical Center and at Vineyard Health, as well are creating educational content for Barbell Medicine. He completed residency at the University of Texas Health Science Center San Antonio and graduated from Eastern Virginia Medical School.
Study Notes
Useful terminology
- Hypogonadism: Impaired gonadal function. In the context of this episode, male testosterone deficiency is a clinical and biochemical syndrome, rather than a diagnosis made from an isolated laboratory flag.
- Screening: Testing asymptomatic people for a condition where earlier intervention might improve outcomes.
- Diagnostic testing: Testing prompted by clinical findings to distinguish between possible explanations.
- Pre-test probability: The likelihood of a condition before testing, informed by clinical assessment. A result updates it to a post-test probability.
- Total testosterone: The circulating concentration of unbound testosterone plus testosterone bound to proteins.
- Free testosterone: The circulating fraction not bound to proteins, measured with an appropriate method or calculated using total testosterone and binding proteins.
- Sex hormone-binding globulin (SHBG): A protein that binds testosterone strongly. Changes in SHBG can alter the relationship between total and free testosterone.
- Hypothalamic–pituitary–gonadal (HPG) axis: The signalling and feedback system connecting the hypothalamus, pituitary and gonads.
- Primary hypogonadism: Deficiency originating in the testes. Secondary hypogonadism: Deficiency associated with insufficient hypothalamic or pituitary stimulation of the testes.
- Testosterone replacement therapy (TRT): Exogenous testosterone used to treat established deficiency, with dose and monitoring matched to the clinical purpose.
- Supraphysiological exposure: Exposure above the physiological range. Evidence from monitored replacement regimens cannot establish the safety of high-dose anabolic steroid use.
1. Start with the reason for testing
Screening and diagnosis answer different questions
- Testing an asymptomatic person is a screening decision. A person who feels well and performs well may seek a testosterone result to “optimise” health or gym performance. Detecting a lower-than-desired concentration does not by itself demonstrate a treatable clinical problem.
- Testing a symptomatic person addresses a differential diagnosis. Loss of previously normal libido, changes in sexual function or characteristic physical findings may make testosterone deficiency more plausible. Fatigue or low mood alone leave a much broader set of explanations.
- The value of screening depends on downstream benefit. A test can be accessible and