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
- -Do I need two separate morning blood draws before we call this hypogonadism?
- -Does this look more like thyroid disease, sleep apnea, or blood sugar instability than an androgen pattern?
- -Does the pattern suggest primary hypogonadism or a secondary, potentially reversible cause?
- -Could sleep restriction, overtraining, crash dieting, alcohol use, or medication effects explain this better than testosterone itself?
Key points to communicate
- •Please document what findings would confirm this cause versus lower confidence.
- •I want an evidence-first workup with clear follow-up criteria.
- •Please note which competing causes should be checked in parallel if results are inconclusive.
- •Please separate metabolic, sleep, autonomic, and medication overlap before narrowing to one cause.
Tests and measurements to discuss
Need the fuller context? Use the test explainers for the measurement itself, or jump back to the tests section on the Testosterone page to see how the tests fit the whole pattern.
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.
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.
Complete Hormone Panel
Total T <300 ng/dL with symptoms = hypogonadism. BUT: T of 350 with low free T and symptoms is also worth treating. Low LH+FSH with low T = secondary (often reversible with lifestyle). High LH+FSH with low T = primary (testicular).
What this helps clarify: Total T <300 ng/dL with symptoms = hypogonadism.
Peer-reviewed references