Total Testosterone vs Free Testosterone
Total testosterone measures all the testosterone circulating in your blood. Most of it isn't free to act on tissue at all, it's bound to sex hormone-binding globulin (SHBG) or, more loosely, to albumin. Free testosterone is the small remaining fraction that isn't bound to anything, and it's the portion that's actually available to bind to receptors and have an effect.
This distinction matters because a total testosterone result can come back looking normal while free testosterone is low, if SHBG happens to be elevated and is tying up more of the hormone than usual. That's why the two are sometimes ordered together, along with SHBG itself, rather than relying on total testosterone alone. See the full peptide bloodwork guide for how this marker fits alongside the rest of a baseline panel.
Reference Ranges
Reference ranges for testosterone are broad and vary by lab, assay, and age group. The numbers below are general, not a diagnosis, and they're only a starting point for reading your own result.
| Population | Typical Total Testosterone Range |
|---|---|
| Adult men | Roughly 300 to 1000 ng/dL |
| Adult women | Roughly 15 to 70 ng/dL |
Ranges differ meaningfully by lab. The exact cutoffs depend on the lab, the assay used, the person's age, and even the time of day the sample was drawn. Always read a result against the specific reference range printed on that lab's own report rather than a number pulled from elsewhere.
Best Time to Test
Testosterone follows a daily rhythm and is typically highest in the morning, which is why a morning draw is the standard convention for this test. Some labs ask for a fasted sample and some don't, so it's worth checking with whichever lab is drawing your blood.
What matters more than fasting status here is consistency. If your baseline was drawn at 8am, a follow-up drawn at 4pm isn't a fair comparison, since the natural daily swing can be large enough to look like a real change when it isn't. Using a consistent time of day between a baseline and a follow-up test matters more than the fasting question for this particular marker.
Relevance to Peptide Protocols
Testosterone bloodwork is commonly tracked alongside growth-hormone secretagogues such as Sermorelin, since these protocols often sit within a broader hormone-optimization plan rather than targeting a single pathway in isolation. It also comes up in the context of exploring TRT-alternative approaches, where testosterone status is one of the baseline markers worth having on hand before deciding on a direction.
As with the other markers in the core panel, a single testosterone result is a snapshot. BioStackIQ's Analyze My Labs tool can read an uploaded report, flag anything outside the printed reference range, and explain what it means in the context of your current protocol.