How to read your hormone blood results

By Nick Peplow·Founder and editor

Last reviewed 27 September 2026· How this site is researched

Every few months, if you are on hormones, a lab sheet comes back with a column of numbers, some of them flagged in bold as too high or too low. Often nobody explains it. The prescriber glances at it, says it looks fine or changes a dose, and you are left with a sheet that seems to say something is wrong.

Reading it well means knowing what the units are, what the lab's flags are measuring you against, and when in your dosing cycle the blood was taken. None of that tells you what your dose should be; that is your prescriber's job. It does let you follow the conversation and ask the right questions.

Two units for each hormone

Different countries report the same hormone in different units, and people compare numbers across forums without noticing.

Estradiol is given in pmol/L (picomoles per litre) in the UK, Europe, Australia and much of Asia, and in pg/mL (picograms per millilitre) in the US. To turn pmol/L into pg/mL, divide by about 3.67. So 500 pmol/L is roughly 136 pg/mL, and 100 pg/mL is roughly 367 pmol/L.

Testosterone is given in nmol/L (nanomoles per litre) outside the US, and in ng/dL (nanograms per decilitre) in the US. To turn nmol/L into ng/dL, multiply by about 28.8. So 1 nmol/L is about 29 ng/dL, and 20 nmol/L is about 577 ng/dL.

If someone online says their estradiol is 400 and yours is 150, check the units before anything else. It may be the same level.

Why the flags look wrong

The lab's reference range, the "normal" column beside each result, comes from a population of cis people, and the lab picks which range to use from the sex on your record. Someone on feminizing hormones recorded as male will often see estradiol flagged high and testosterone flagged low, when both are exactly where their prescriber wants them. Change the sex on your record and the flags flip, often onto other tests, such as hematocrit or kidney function, which also have sex-specific ranges.

So a bold figure is not a verdict. A testosterone of 20 nmol/L flagged "high" against a female range may be exactly where a prescriber wants it for a trans man. What matters is the target your prescriber is working to.

What prescribers usually aim for

Guidelines such as the Endocrine Society's commonly cite rough targets:

• Feminizing hormones: estradiol of roughly 100 to 200 pg/mL (about 370 to 730 pmol/L), and testosterone suppressed to under about 50 ng/dL (under about 1.7 nmol/L)
• Masculinizing hormones: testosterone in roughly the typical adult male range, often given as something like 400 to 700 ng/dL (about 14 to 24 nmol/L)

Treat those as the shape of the target, not a line to hit. Clinics interpret them differently, some people feel best or change most outside them, and plenty of prescribers put more weight on how you feel and what is changing than on the number. A level far above the range is not a shortcut to faster changes; on estrogen in particular it mostly adds risk. Ask what your target is, in the units your lab uses, and write it down.

When the blood was taken changes the number

Hormone levels rise after a dose and fall towards the next one, the peak and trough. The same person can look high one day and low a week later without anything being wrong.

• Injections swing the most. A test a day or two after an injection shows something close to the peak; a test just before the next one shows the trough. Many prescribers want the trough, because it is easiest to compare over time.
• Tablets peak within hours. A test soon after a morning dose reads higher than one taken before it, and tablets held under the tongue spike and fall faster still.
• Long-acting injections and pellets, such as testosterone undecanoate, change slowly over weeks or months, so the test is usually timed just before the next dose.
• Gels and patches are steadier, but a sample taken from the arm you just applied gel to can come back falsely high, sometimes wildly so.

The single most useful thing you can do is keep the timing the same every time and tell whoever takes the blood when your last dose was. Write it on your own copy of the results too.

The other numbers on the sheet

Hormone levels are only part of what is being watched. Depending on your plan, the same sheet might include:

• Hematocrit and haemoglobin, on testosterone, because it raises red cell count
• Potassium and kidney function, on spironolactone
• Prolactin, on estrogen and especially cyproterone
• Liver function, on some anti-androgens and oral medicines
• Lipids and sometimes blood sugar, as part of longer-term health checks
• SHBG, when the total hormone level and how you feel don't match

Blood tests and monitoring sets out what is usually checked, and how often, on each plan.

Questions worth asking about any result

• What is my target for each hormone, in the units this lab uses?
• Do you want the test at trough, peak or mid-cycle, and how many hours or days after my dose is that?
• Which of these flags matter for someone on my hormones, and which can I ignore?
• Is anything moving in a direction you want to watch, even if it is in range?
• What would make you change my dose, and what would you change it to?

A prescriber who answers those plainly is telling you something good about how they work. And if a result has you worried, ask them rather than adjusting anything yourself: a single odd number is often a timing problem, and the fix is usually a repeat test.

This is general information, not medical advice. For what hormones do and how they are taken, see feminizing hormones and masculinizing hormones, and if you are at the beginning, start here.