Starting testosterone replacement therapy (TRT) is rarely a one-off decision. Once treatment begins, the questions change: is the dose right, is the body handling it well, is anything drifting that should be looked at? Regular blood tests are how those questions are answered. This guide explains what is usually monitored on TRT and what the Testosterone Replacement Therapy Profile in the BPR catalogue includes.
Why monitoring matters
LML states plainly that testosterone levels must be checked regularly by anyone using testosterone for any reason, and that it is possible to have too much as well as too little. The Endocrine Society guideline recommends that men on TRT are monitored with a standardised plan that includes symptoms, side effects and adherence, serum testosterone, haematocrit, and an evaluation of prostate cancer risk during the first year of treatment (Bhasin et al., 2018). The guideline suggests aiming for testosterone in the mid-normal range.
The European Association of Urology's 2025 update on male sexual and reproductive health also emphasises appropriate indications and structured follow-up for men on testosterone therapy (Salonia et al., 2025).
The key markers
Testosterone, free testosterone and SHBG
These confirm whether the dose is giving levels in the intended range. Timing depends on the type of treatment (gels, injections or other forms), so your prescriber will tell you when in the dosing cycle to test. Free testosterone is calculated from total testosterone, SHBG and albumin.
Haematocrit and haemoglobin
Testosterone stimulates red blood cell production. A 2025 review explains that TRT can raise haematocrit and haemoglobin, and that very high levels may increase the risk of blood clots, so these need close monitoring (Fink et al., 2025). The review also notes that the way testosterone is given seems to influence how much haematocrit rises. Elevated haematocrit is one of the situations where the Endocrine Society advises against starting TRT (Bhasin et al., 2018).
PSA
Prostate-specific antigen (PSA) is part of evaluating prostate risk during the first year. The Endocrine Society guideline lists a raised PSA among the situations that need urological evaluation before starting therapy (Bhasin et al., 2018).
Oestradiol, LH and FSH
Some testosterone is converted to oestradiol. LH and FSH, the pituitary signals that drive natural production, usually fall on TRT. Your doctor may use these to understand how your body is responding.
What the TRT Profile includes
The Testosterone Replacement Therapy Profile from LML brings these together with a broader health check. It includes:
- testosterone, SHBG, albumin, free testosterone (calculated) and free androgen index;
- oestradiol, LH, FSH and prolactin;
- a full blood count, including haemoglobin and haematocrit;
- PSA;
- cholesterol profile (total, LDL, HDL, non-HDL and triglycerides) and HbA1c;
- thyroid function (TSH, free T4 and free T3);
- liver and kidney markers and ferritin.
Between full reviews, some men only need testosterone levels checked; the Testosterone Plus Profile covers total and free testosterone with SHBG.
How often?
The Endocrine Society plan focuses on regular checks in the first year, then ongoing review (Bhasin et al., 2018). In practice, many men on TRT test every 3 to 6 months, especially early on or after a dose change, and less often once things are stable. Talk to your prescriber about the right schedule for you: they know your treatment and history.
