Clinician handoff
Testosterone
Designed for a 60-second scan in primary care. Use this to explain why this theory fits, what would weaken it, and which tests are most worth discussing.
Why this still fits
I want to evaluate whether low testosterone is contributing to my brain fog, but I also want to rule out sleep apnea, thyroid disease, blood sugar issues, and other reversible drivers before assuming TRT is the answer.
What would weaken it
- -No low-libido, low-recovery, body-composition, or drive changes traveling with the fog.
- -Hormone testing isn't convincing and the picture fits sleep apnea, depression, alcohol, or thyroid disease better.
- -The cognitive symptoms behave independently of the broader androgen story.
Key points to communicate
- •I want to know whether low testosterone is actually central here or just one possible amplifier.
- •Please separate hormone effects from sleep apnea, metabolic strain, alcohol, and depression.
- •If testosterone is relevant, I want to know which measurements and timing issues matter most.
Bring this to the visit
- •Testosterone lab results (total and free) with the time of day drawn (must be morning fasting).
- •LH, FSH, and prolactin results if available.
- •Symptoms beyond fog: libido changes, fatigue, muscle loss, mood changes, body composition.
- •Current medications including opioids, steroids, and any hormone therapy.
Useful screening structure
- -Morning fasting total and free testosterone (drawn 8-10 AM).
- -LH and FSH to distinguish primary from secondary hypogonadism.
- -Prolactin level to rule out prolactinoma if testosterone is low.
Tests and measurements to discuss
Total + Free Testosterone
What this helps clarify: This panel should be used selectively.
Range context
Sex- and assay-specific context
How to use the result
Save the result with date and symptoms from the same week.
SHBG
What this helps clarify: High SHBG = less free testosterone available
Range context
10–57 nmol/L (men)
How to use the result
Save the result with date and symptoms from the same week.
LH / FSH
Estradiol
What this helps clarify: Primary estrogen - decline impairs hippocampal function
Range context
Varies by cycle phase
How to use the result
Save the result with date and symptoms from the same week.
Prolactin
What this helps clarify: Elevated prolactin suppresses testosterone
Range context
2–18 ng/mL (men)
How to use the result
Save the result with date and symptoms from the same week.
Questions to ask directly
- •Is my testosterone genuinely low, or is it borderline with an unclear clinical significance?
- •Should we investigate the cause of low testosterone (primary vs secondary) before treating?
- •What are the risks and benefits of TRT for my specific profile?
- •Are there medications (opioids, steroids) suppressing my testosterone that we could address first?
Functional impact snapshot
- -Rate fog severity, energy, and libido together - do they move in parallel?
- -Track whether symptoms improve on TRT within the expected 6-12 week timeframe.
- -Note time of day: are symptoms worst in the morning when testosterone is highest or lowest?
Escalate instead of self-managing if
- •Visual field defects with low testosterone suggesting pituitary mass.
- •Rapidly developing symptoms with very low testosterone - needs urgent endocrine workup.
- •Polycythemia (elevated hematocrit) on testosterone replacement therapy.
Peer-reviewed references
- 1. Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018. [DOI]
- 2. Resnick SM, et al. Testosterone Treatment and Cognitive Function in Older Men With Low Testosterone and Age-Associated Memory Impairment. JAMA. 2017. [DOI]
- 3. Leproult R, Van Cauter E. Effect of 1 Week of Sleep Restriction on Testosterone Levels in Young Healthy Men. JAMA. 2011. [DOI]