Testosterone panels for men: what total, free, and SHBG mean together
The short version: testosterone is not one number — it is three numbers that only make sense together.
TL;DR
- A complete testosterone panel includes total testosterone, free testosterone, and SHBG.
- SHBG is the protein that binds testosterone in the blood and changes how much is available to tissues.
- Reading just total testosterone in isolation can miss real clinical issues hiding in the SHBG number.
What it is
A testosterone panel (in plain English: a blood test that measures the body’s primary male sex hormone and the proteins that carry it) typically includes three values. Total testosterone is everything in the blood. Free testosterone is the portion not bound to a carrier protein. SHBG (in plain English: sex hormone-binding globulin, a protein that latches onto testosterone in the bloodstream) determines how much of the total is available to act on tissues.
How it works
Think of testosterone like passengers on a city bus. Total testosterone counts everyone on the bus. SHBG is a one-armed escort: every passenger SHBG holds onto cannot get off at any stop. Free testosterone is the count of passengers who are unaccompanied and free to step out and do work. When SHBG is high, the bus may be full of people, but most of them are escorted and unavailable. When SHBG is low, even a half-full bus can deliver more workers to the right stops. Tissues respond to free testosterone, not bus headcount.
Who asks about it
People come to this topic after a lab result that does not match how they feel — or after a clinician orders “free testosterone” and the explanation is rushed. The disconnect is real and common. About 1 in 5 men evaluated for symptoms of low testosterone show normal total testosterone but elevated SHBG and low free testosterone, according to clinical practice patterns (Sigalos and Pastuszak, J Clin Endocrinol Metab, 2018).
What the research says
The Endocrine Society’s clinical practice guideline for testosterone therapy recommends starting with two morning total testosterone measurements; if those are borderline or do not match the clinical picture, adding free testosterone (calculated or measured) and SHBG (Endocrine Society, Testosterone Therapy Guideline). SHBG is influenced by age, thyroid status, insulin resistance, and certain medications, which is why the three numbers tell a fuller story than any one alone.
What to know before considering it
Testosterone panels should be drawn in the morning, ideally between 7 and 10 a.m., and confirmed with a second draw before any treatment decision. Insulin resistance, obesity, and acute illness all shift the numbers. Treatment decisions should be based on the full clinical picture, not a single result.
The Halftime POV
A single testosterone number is incomplete information. Three numbers together — total, free, and SHBG — are what a serious workup looks like. The labs are cheap. The interpretation is the work.
Related reading:
- Biomarkers commonly tracked during peptide protocols
- The baseline blood panel: what to test before any peptide protocol
- Testosterone vs peptide secretagogues: how they differ
FAQ
Q: What is the difference between total and free testosterone? A: Total testosterone measures all the testosterone in the blood, both bound and unbound. Free testosterone measures only the unbound portion that is biologically active. Both numbers can move independently depending on SHBG.
Q: What does SHBG do? A: SHBG (sex hormone-binding globulin) is a protein that binds to testosterone in the blood. When SHBG is high, more testosterone is bound and less is free. When SHBG is low, more testosterone is free even if total testosterone looks normal.
Q: Should I check just total testosterone or all three? A: All three together give a clearer picture. Total testosterone alone can be misleading when SHBG is unusually high or low. The Endocrine Society guidelines recommend checking total testosterone first and adding free testosterone or SHBG when the clinical picture and total result do not match.
Disclaimer
This article is educational and is not medical advice. Compounded medications are not FDA-approved. Clinical outcomes depend on individual factors and require physician evaluation. Results vary. Halftime Health is launching soon — join the waitlist to get updates.
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