Blood Tests and Monitoring

What gets measured

The exact panel depends on the medicines you take and on your prescriber, but the core is similar almost everywhere.

On feminizing hormones: estradiol, the main form of estrogen, to check the dose is reaching a useful level; testosterone, to check it has been suppressed, whether by estrogen alone or with an anti-androgen; and, depending on the medicines, a few extras. Spironolactone can raise potassium and affect the kidneys, so both are checked. Cyproterone acetate is usually monitored with prolactin and liver tests. Some prescribers check prolactin on estrogen alone too.

On masculinizing hormones: testosterone, to check the level sits in the intended range, and hematocrit with haemoglobin, because testosterone makes the body produce more red blood cells and thicker blood raises the risk of clots. Many prescribers also check estradiol, lipids (cholesterol) and liver function.

On either: a baseline set before you start, so later numbers have something to be compared against. That often includes kidney and liver function, lipids, blood sugar and a full blood count. Some prescribers also check SHBG, the protein that carries sex hormones in the blood, when a total hormone level and how you feel don't match.

Not a blood test, but part of the same check: blood pressure and weight, usually at each review. Both move on hormones, and both feed into the longer-term picture in long-term health.

How often

The pattern most guidelines describe is more often early, less often later.

In the first year, tests commonly come roughly every three months. That is when the dose is being found, and when anything unexpected tends to show up.

After the first year, once the dose is stable and the results are steady, most people drop to one or two tests a year.

After any change, whether a new dose, a new medicine or a new way of taking it, expect a test a few weeks to a few months later to see where it has landed.

After the testes or ovaries are removed, the panel usually changes. Most people on feminizing hormones stop their anti-androgen, so potassium or prolactin checks tied to it may drop away, and the dose of estrogen or testosterone is often rechecked in the months after surgery. Hormones and surgery covers what changes.

Guidelines such as the Endocrine Society's and WPATH's Standards of Care describe schedules along these lines, and individual prescribers adapt them. If you are on an informed consent route or a telehealth service, the monitoring is often built into the subscription; on a public system, the tests may be done by your GP rather than the specialist.

When you get your first results

Ask for a copy of the actual numbers, units and reference ranges, not just "all fine". Keep them in one place. When you change prescriber, move country or book surgery, that history is worth more than any single result.

Timing and units

Two things make results confusing, and neither means anything is wrong. Levels rise after each dose and fall before the next, so when the blood was drawn changes the number, especially on injections. And labs report the same hormone in different units in different countries, then flag it against a reference range for the sex on your record, not for someone on HRT.

How to read your hormone blood results covers both: the conversions, the target ranges guidelines cite, and why a bold "high" is often exactly where your prescriber wants you.

When you book a test

Ask your prescriber what point in your dosing cycle they want the blood taken at, and write down when you last dosed. If you use gel, ask which arm the blood should come from. A result without that detail is much harder to interpret.

On the day of the test

A few small things make a result easier to trust:

• Ask whether you need to fast. Hormone levels don't need it, but some prescribers fold cholesterol or blood sugar into the same draw, and those can be read differently after a meal.
• Drink water beforehand, especially on testosterone. Being dehydrated concentrates the blood and can make hematocrit read higher than it really is.
• Take your dose as your prescriber asked. Some want the test before your morning tablet or just before your next injection; some don't mind. Don't skip or delay a dose to "get a good number".
• If you use gel, use the other arm for the blood draw, or tell the phlebotomist, because gel on the skin near the needle can make estradiol or testosterone read falsely high.
• Note the time and your last dose on your phone. It takes ten seconds and makes the result readable for anyone later.

Where tests are done, and paying for them

Depending on your system, blood may be drawn at your GP surgery, a hospital clinic, a high-street or commercial lab, or a home kit you post back. On a public system with shared care, the specialist often asks your GP to arrange it. Telehealth services usually send a form for a local lab.

If you're paying, blood tests are often the biggest running cost of hormones in the first year, more than the medicine. Ask whether your prescriber's fee includes them, and whether a cheaper lab can run the same panel. Cost and insurance has rough prices. Whoever draws the blood, make sure the results go to the person who prescribes, and ask for your own copy.

What prescribers watch for

Most results simply confirm the dose is working. The ones that lead to a change or a follow-up are few and well known.

On testosterone, the main one is a rising hematocrit. Prescribers commonly start watching at around 50 per cent and act somewhere around 50 to 54 per cent (guidelines differ), usually by changing the dose or the way it is taken. Smoking, sleep apnoea and taking blood when dehydrated can all push it up. Masculinizing hormone risks explains why it matters.

On spironolactone, it is potassium and kidney function. On cyproterone, it is prolactin and liver function. On estrogen, a very high or very low estradiol is a reason to review the dose, and a testosterone that is not suppressed is a reason to look at the anti-androgen or the estrogen dose. What those results mean for your health is covered in feminizing hormone risks.

A flagged result is a reason for a conversation, not an emergency. What happens next is your prescriber's decision, and it is one of the main reasons to have one.

If you take hormones without a prescription, usually because of waiting lists or cost, the tests matter more, not less, because nobody else is watching your levels, potassium or hematocrit. In many countries you can order tests privately without a referral, and some GPs will monitor hormones you already take while you wait for a specialist. A bridging prescription is the formal version of that; gender clinics covers how it works.

Frequently asked questions

How often do I need blood tests on HRT?

Commonly around every three months in the first year, then once or twice a year once your dose is stable, plus one after any change. See how often.

Why is my estradiol so different from last time?

Often it is timing. Levels rise and fall between doses, especially with injections, so a test taken at a different point in the cycle gives a different number. See timing and units.

What estradiol or testosterone level should I be at?

Guidelines give rough target ranges, and your prescriber sets yours. How to read your hormone blood results gives the ranges in both units.

My result is flagged as high. Is that bad?

Not necessarily. The lab's reference range is usually for the sex on your record, not for someone on HRT. See timing and units and what prescribers watch for.

Do I need to fast before an HRT blood test?

Not for the hormone levels themselves, but sometimes for cholesterol or blood sugar on the same draw. Ask when you book. See on the day of the test.