Testosterone replacement therapy is a common form of gender affirming care. Some healthcare providers raise concerns about blood issues such as high haematocrit, clotting problems, or other risks. In reality, most people do well on testosterone when treatment is monitored carefully. Many of the concerns come from misunderstanding how testosterone affects the body.
Haematocrit and Polycythaemia
Haematocrit: The percentage of your blood that's made up of red blood cells. Testosterone tends to increase red blood cell production.
Polycythaemia: A medical term for when haematocrit becomes too high and could lead to health issues. Not the same as a normal increase with testosterone.
Are trans men more at risk?
The evidence shows trans men under physiological doses of testosterone (i.e. doses that aim for normal male hormone levels) respond similarly to cisgender men.
Major medical guidelines (like WPATH, Endocrine Society) do not say blood disorders or clotting history should automatically prevent someone from getting testosterone. They do recommend careful risk assessment and monitoring.
What to watch out for / manage
Threshold for concern
Generally, if haematocrit goes above about 54-55%, that's when action is often considered. But it depends on overall health and risk factors.
How to manage high haematocrit:
Lowering the dose of testosterone.
Changing how you give testosterone (for example, using patches or gels instead of injections).
Lifestyle changes: stop smoking, make sure you're hydrated, etc.
More frequent blood tests, especially early on.
What we recommend
Do an individualised risk assessment that looks at personal history (e.g. clotting, cardiovascular risk factors) and current health.
Do a blood test every 3 months for the first year, and then annually when things are stable.
Keep testosterone in a range that mimics typical male hormone levels – don't go beyond what is medically normal.
What to do if you run into problems or resistance
If your healthcare provider refuses or hesitates to prescribe testosterone replacement therapy solely because of fears around blood issues, you can:
Ask for a written explanation and medical evidence.
Ask for a second opinion or referral to a trans-health specialist or endocrinologist.
Keep records of your interactions.
Important reminders
- Slight increases in haematocrit are expected with testosterone – it's not automatically bad.
- Never stop testosterone without medical supervision. Changes to dose or method should be discussed with your provider.
- If you have symptoms like chest pain, trouble breathing, leg swelling, persistent dizziness, seek medical help.
To use the finger prick test, you need to be 16 or older and not taking spironolactone. Vitall, the service provider, will send your blood test results directly to your email address.
If you’re taking spironolactone, you’ll need an intravenous blood sample. You can get this through an online blood test service of your choosing, through your GP if they’re willing to help, or at a private clinic/hospital.
If you need a Blood Test Referral Letter to advise your GP or healthcare provider, you can purchase one through the Treatment Recommendation form for £20 or order it separately here. The letter explains why you need blood tests and which ones you’ll need to get.
When you have your results, please submit them in the Treatment Recommendation form for analysis.