Blood tests on TRT: which labs, and when
Protocol Unlocked editorial team · November 15, 2026 · 3 min read
Testosterone therapy is one of the few things people track where bloodwork is the main way to know it's going right. The Endocrine Society's 2018 guideline sets out what to check and when. Here is that schedule in plain language, plus the parts that are common practice rather than guideline.
Before starting
The guideline recommends treating only men who have symptoms of low testosterone and low levels on two separate early-morning tests. Testosterone is highest in the morning and varies from day to day, so one low result isn't enough.
A baseline panel before the first dose makes every later result meaningful. It usually includes total testosterone, hematocrit and PSA (for men in the screening age range), along with whatever else your clinician wants as a starting point.
The guideline schedule
| When | What | Why |
|---|---|---|
| 3–6 months after starting | Testosterone | Check you've reached the target range |
| 3–6 months after starting, then yearly | Hematocrit | Testosterone raises red blood cell production |
| 3–12 months after starting | PSA (men 55–69, or 40–69 at higher risk) | Prostate monitoring |
| Yearly after that | Testosterone and hematocrit | Make sure things stay put |
The guideline's target is a testosterone level in the mid-normal range, not the top of it.
What each marker tells you
- Total testosterone: whether the dose is doing what it should. A result only means something if you know when it was drawn (see below).
- Hematocrit: the share of your blood made up of red cells. It commonly rises on testosterone. The guideline says a hematocrit above 54% is a reason to stop treatment until it comes down, then restart at a lower dose. We cover this in more depth in a separate post.
- PSA: a prostate marker. Testosterone can raise it a little; a large or fast rise needs a urologist's look.
Many clinics also check estradiol, SHBG, free testosterone and lipids (LDL, HDL, triglycerides). These are common practice, not part of the guideline's core list, but they help explain symptoms and results.
When to draw blood between injections
Timing changes the result more than most people expect.
- Weekly or twice-weekly cypionate or enanthate shots: draw midway between injections. Drawing the day after a shot catches the peak; drawing right before the next one catches the low point.
- Shots every 1–3 days: levels stay steadier, so timing matters less.
- Whatever you do, do it the same way every time. Two results drawn at different points between shots can't be compared.
After a dose change
Levels settle about 5 weeks after a change. Re-testing 6–12 weeks after a dose change is common practice, so the next result reflects the new dose rather than the old one.
Don't read one result alone
A single number is a snapshot. What matters is the trend:
- Is hematocrit creeping up test after test, even if each value is "in range"?
- Did testosterone fall because the dose changed, or because the blood was drawn at a different point between shots?
- Did a change in symptoms line up with a change in labs?
Charting every marker over time, with the start of each compound marked on the chart, makes these questions easy to answer.
What the big safety trial found
In TRAVERSE, 5,246 men at high heart risk took testosterone or placebo. Testosterone did not increase heart attacks or strokes, but there were more cases of atrial fibrillation, blood clots in the lungs and acute kidney injury. It's a reason to keep up with monitoring and report new symptoms, not a reason to skip treatment your clinician recommends.
How the app helps
Protocol Unlocked builds a blood test plan from what you take: for testosterone it uses the schedule above, labels which parts are guideline and which are common practice, and reminds you when a draw is due. You can import a lab report from a PDF or photo, chart each marker against your lab's range, and set your own limits, such as a hematocrit ceiling.
See our testosterone library page for the research summary and interactions, and the blood tests guide for a baseline panel checklist.
Sources
- Bhasin 2018, J Clin Endocrinol Metab (Endocrine Society guideline). PMID 29562364
- Lincoff 2023, N Engl J Med (TRAVERSE). PMID 37326322
- Snyder 2016, N Engl J Med (Testosterone Trials). PMID 26886521
General information, not medical advice. Doses mentioned are what drug labels or trials used, not recommendations. Talk to a clinician before starting or changing anything.