The timeline at a glance
| When | What to check | Why |
|---|---|---|
| Before starting | Total testosterone twice (early morning, same lab); LH; prolactin if LH is low or low-normal; hemoglobin and hematocrit; PSA if over 40; estradiol if breast symptoms; fertility evaluation if you want children | Confirm the diagnosis, find the cause, and set a safe baseline |
| First follow-up 2 to 4 weeks (gels) or after 3 to 4 injection cycles | Total testosterone | See whether you reached the target range and adjust the dose |
| Within 3 months | Symptom review | Decide whether treatment is helping |
| 3 to 6 months | Hematocrit; stop-or-continue discussion if no symptom benefit | Red cell counts typically climb for about six months, then plateau |
| Every 6 to 12 months | Total testosterone; hematocrit; PSA by shared decision; estradiol only if symptoms or on an aromatase inhibitor | Keep levels in range and catch problems early |
| Bone density, if low at baseline | Repeat scan 1 to 2 years after starting | Track whether bone density responds |
Intervals come from the American Urological Association guideline (statements 29 to 31 and Table 7) and, where noted, the Endocrine Society guideline. Both are 2018 documents; the AUA reconfirmed its guideline in 2024.
Before you start
Baseline testing does two jobs: confirming that low testosterone is the real problem, and giving you a starting point to compare against.
- 1Total testosterone, twice. Two early-morning measurements on separate occasions, ideally at the same lab and with the same assay so results are comparable.
- 2LH, and prolactin if LH is low. LH tells you whether low T is primary or secondary; prolactin is checked when testosterone is low and LH is low or low-normal.
- 3Hemoglobin and hematocrit. The AUA recommends them before offering therapy. If hematocrit is above 50% to begin with, treatment should be withheld until the cause is explained. Sleep apnea is one possible cause.
- 4PSA, if you are over 40. Measured before starting to exclude prostate cancer. See PSA and TRT.
- 5Estradiol, if you have breast symptoms (the AUA also lists it as optional for everyone).
- 6Fertility evaluation, if you want children. Testosterone suppresses sperm production; see TRT and fertility.
Many providers add a broader panel (thyroid, lipids, metabolic markers, vitamin D). Our starter panel lists a typical one. Those extras are reasonable, but the guideline items above are the ones that drive safety decisions.
The first follow-up, by format
The right moment for the first re-check depends on how the testosterone is delivered. These are the AUA's suggested timings:
| Format | First testosterone check |
|---|---|
| Gels, patches, nasal gel | 2 to 4 weeks after starting |
| Oral capsules | 3 to 6 hours after the morning dose, at least 7 days after starting or changing the dose |
| Short-acting injections (cypionate, enanthate) | After 3 to 4 injection cycles, ideally mid-cycle |
| Long-acting injection (undecanoate) | Once steady state is reached, halfway between the first two injections |
| Pellets | 2 to 4 weeks after implant, then again at 10 to 12 weeks |
| Anastrozole, clomiphene, or hCG | No sooner than 4 weeks |
The goal at this first check is the middle of the normal range. The AUA describes this as the middle tertile, roughly 450 to 600 ng/dL, using the lowest dose that gets there. Some clinics aim higher; ask what your target is and why. Dosing questions belong to your prescriber, and the delivery methods section explains how formats differ.
At 3 to 6 months
This is the checkpoint that matters most. By now your dose should be settled, and two questions need answers:
- Is it working? The AUA says symptoms should be re-evaluated within three months. If testosterone has normalized but symptoms or signs haven't improved after three to six months, it recommends discussing stopping therapy, except where bone density loss is documented or unexplained anemia has improved on treatment. See which symptoms treatment is most likely to fix.
- Is it safe so far? Hematocrit tends to rise for about six months and then plateau, so this is when a rise shows up. As summarized from the Endocrine Society guideline, hematocrit is checked at baseline and at 3 to 6 months. Check your blood pressure too; see blood pressure on TRT.
The AUA does not recommend using validated questionnaires to monitor your symptom response, so expect a conversation rather than a score.
Ongoing, every 6 to 12 months
Once you are stable, the AUA's follow-up table calls for:
- Total testosterone every 6 to 12 months.
- Hemoglobin and hematocrit every 6 to 12 months, or sooner based on prior values, to keep hematocrit below 54%. The Endocrine Society summary we reviewed says annually after the 3 to 6 month check, so the two guidelines are close but not identical.
- PSA by shared decision-making. For men 40 to 54, routine screening isn't recommended unless risk is higher; for men 55 to 69, biennial screening should be considered. Men with a history of prostate cancer follow the same schedule as other men, though clinicians may test more often.
- Estradiol only if breast symptoms or gynecomastia develop, and for men on aromatase inhibitors. See managing estrogen.
- Prolactin only if you are being treated for high prolactin.
- Bone density: if baseline scanning showed bone loss, repeat 1 to 2 years after starting, then every 2 to 5 years if it normalizes.
Lipids are a gap in the guidelines: the AUA found the evidence on lipid effects inconclusive and sets no interval. Many clinicians check them as part of a general annual panel anyway.
What results should trigger
| Result | Typical response (per guidelines) |
|---|---|
| Hematocrit above 50% before starting | Withhold treatment until the cause is explained |
| Hematocrit at or above 54% on treatment | Intervention. If on-treatment testosterone is high, lower the dose first. If testosterone is low or normal, check SHBG and free testosterone; if those are normal too, refer to hematology. The Endocrine Society summary adds pausing therapy until it falls, then restarting lower. |
| Estradiol above 40 pg/mL | Referral to an endocrinologist (AUA) |
| PSA over 4.0 ng/mL (confirmed), or a rise of more than 1.4 ng/mL in a year | Urology referral (as summarized from the Endocrine Society guideline) |
| Testosterone above or below target | Dose adjusted; the aim is mid-normal range |
| Normal testosterone but no symptom relief after 3 to 6 months | Discuss stopping (AUA) |
Interpretation belongs to your clinician; these are the conversations the numbers should start, not instructions to act on your own. Our side effects guide explains why hematocrit gets so much attention.
Getting accurate draws
- Draw in the morning. Testosterone peaks around 3 to 8 a.m. in men with a typical sleep pattern. Your timing relative to your dose matters just as much, so use the table above.
- Use the same lab and assay each time, so changes reflect you and not the method.
- Write down when you last dosed. Note the time of your last injection or gel application on the lab form or in your notes so results can be interpreted correctly.
- Avoid testing while ill. Acute illness can artificially lower testosterone, by about 10% on average.
- Fasting: the guidelines differ. The Endocrine Society recommends a fasting morning draw to confirm the diagnosis; the AUA says fasting is not recommended before testing. Follow your clinician's instruction.
- Use blood tests. Saliva testing isn't considered reliable for this, and you should check with your clinician before substituting an at-home kit for a lab draw.
What this tells you about a provider
Bloodwork is the clearest test of whether a provider takes safety seriously. A program that prescribes without baseline hematocrit, has no plan for the 3 to 6 month check, or doesn't tell you when your next labs are due is a red flag. This is why our Atlas Score weights medical safeguards at 30%, the largest share. See how we score providers and the ranked list.
Labs also drive cost: repeat panels can cost more than the medication at some providers. See costs people forget before you sign up, and ask any provider for the full lab schedule and its price in writing. Our free TRT Checklist lists the labs to expect and the questions to ask; get it by joining the weekly briefing below.
Sources
- Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and management of testosterone deficiency: AUA guideline. J Urol. 2018;200(2):423-432 (validity reconfirmed 2024); statements 2, 9, 11, 12, 14, 15, 22, 29 to 31 and Table 7. American Urological Association
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. PubMed. Monitoring timing and thresholds as summarized in this primary care summary.
- Farzam K. Individualizing injectable testosterone replacement therapy in primary care: pharmacokinetics, symptom stability, safety monitoring, and injection frequency. Cureus. 2026;18(6):e110570. PubMed