Hormones

TRT hormone markers: what each one is and why it is on the panel

Total and free testosterone, SHBG, estradiol, LH, FSH, prolactin and DHT, in plain words, with which ones are for diagnosis and which ones get watched once you are on a protocol.

Updated 2026-11-08 · Part of the Magno guides

TL;DR. A TRT blood panel has two jobs: first to show whether testosterone is truly low and why, then to show how your body is handling a protocol. Total testosterone, free testosterone, SHBG and estradiol are the hormone markers most panels repeat. LH, FSH and prolactin matter most before starting, and DHT is an optional extra.

Made by Theos Studio, which builds Magno, an iPhone log for bloods and protocols. This page explains what the numbers are. It is not medical advice; decisions belong to you and your clinician.

Which hormone markers are on a TRT panel?

Most panels include total testosterone, free testosterone, SHBG and estradiol. Before treatment, clinicians usually add LH, FSH and prolactin to work out the cause of low testosterone. Some private panels add DHT. Commercial panels differ: Medichecks' TRT check lists testosterone, calculated free testosterone, SHBG, oestradiol, prolactin and PSA alongside a full blood count, while the panel described by Testing.com centres on total and free testosterone, a sensitive estradiol, a blood count and a metabolic panel. Neither lists LH or FSH.

The hormones at a glance:

• Total testosterone. All the testosterone in the sample. Used to diagnose a deficiency and to check the level on treatment. More on total testosterone.
• Free testosterone. The small share not bound to proteins. Most useful when SHBG is unusual or total testosterone is borderline. More on free testosterone.
• SHBG. The protein that binds testosterone. It explains the gap between total and free. More on SHBG.
• Estradiol. The estrogen made from testosterone. Watched on a protocol because it rises with testosterone. More on estradiol.
• LH and FSH. Pituitary signals to the testes. Mainly a diagnosis test. LH, FSH.
• Prolactin. A pituitary hormone. Checked when the cause of low testosterone looks pituitary. More on prolactin.
• DHT. A stronger androgen made from testosterone. An optional add-on on some private panels. More on DHT.

Why is testosterone tested twice before treatment?

Because one reading is not enough to be sure. The Endocrine Society's 2018 clinical practice guideline (Bhasin et al., J Clin Endocrinol Metab) says clinicians should measure total testosterone on two separate mornings while fasting. Its evidence review puts it plainly: at least two measurements were needed to diagnose a deficiency with confidence.

What do free testosterone and SHBG add?

They tell you how much of the total is available. SHBG holds most testosterone tightly, so the same total can mean quite different free levels. The same guideline recommends a free testosterone result in men whose total is near the lower limit of normal or who have a condition that changes SHBG. Some labs calculate free testosterone from other results rather than measuring it directly; Medichecks, for example, labels theirs as calculated.

Why do LH and FSH matter before starting?

They show where the problem sits. The 2018 guideline recommends measuring LH and FSH to tell primary hypogonadism (the testes) from secondary hypogonadism (the pituitary or hypothalamus). When the cause looks secondary, it also lists prolactin and iron saturation among the next tests. That is why a baseline panel is worth keeping: it is the only record of how your own hormones ran before treatment.

On a protocol, LH and FSH often read very low, because the brain sees testosterone arriving from outside and stops signalling. The LH guide explains what that low reading means.

Which hormones get watched once you are on a protocol?

Mainly total testosterone, often with free testosterone and SHBG, plus estradiol. The guideline suggests aiming for testosterone in the mid-normal range on treatment and includes measuring testosterone and hematocrit in its plan for the first year. Hematocrit is a blood count, not a hormone, but it is the result most likely to prompt a conversation with your doctor; the hematocrit guide covers it. For estradiol, a sensitive assay reads men's levels more accurately; see estradiol on TRT without an aromatase inhibitor.

What can throw hormone results off?

Timing and supplements, mostly.

• Time of day. Medichecks asks for samples between 6am and 10am, and for prolactin at least an hour after waking.
• Where you are in the injection cycle. A draw soon after an injection reads higher than one just before the next. Drawing at the same point each time keeps results comparable; reading your first TRT blood test covers this.
• Biotin. The 2018 guideline notes that LH and FSH assays are susceptible to biotin interference, and says to stop biotin supplements for at least 72 hours before testing. Biotin is common in hair, skin and nail products.

What do people commonly discuss with a doctor?

• Whether the baseline included LH, FSH and prolactin, and what they showed.
• Whether free testosterone was measured or calculated.
• Where in the injection cycle each draw was taken.
• Whether the estradiol result came from a sensitive assay.
• Any biotin or other supplements taken before the draw.

Keep every result on one line

Hormone numbers move with timing, assay and lab, so a single result says little. Seeing each marker across every draw, with the change since last time, is what makes the pattern visible to you and your doctor. Magno is a log for exactly that: it never suggests what to take or how much. If it helps, get Magno on the App Store.