Why do we check oestrogen and testosterone levels?
For people who are receiving oestrogen or testosterone for their gender affirming medical treatment, regular blood tests for oestrogen and testosterone levels are recommended. This is to ensure that the levels of oestrogen and testosterone in the body are within the desired reference ranges for achieving optimal feminisation or masculinisation effects while also minimising any health risks. The doses of oestrogen or testosterone can then be adjusted accordingly.
What are the recommended reference ranges?
The following table summarises the recommended reference ranges.
Pathway | Oestradiol (pmol/l) | Testosterone (nmol/l) |
Feminising — puberty induction under 14 | 176–345 | <2 |
Feminising — age 14–16 or slow transition | 176–631 | <2 |
Feminising — full feminisation | 176–936 | <2 |
Masculinising — puberty induction under 14 | <176 | 5–15 |
Masculinising — age 14–16 or slow transition | <176 | 5–20 |
Masculinising — full masculinisation | <176 | 5–30 |
What can happen if my hormone levels are outside the desired reference ranges?
If you are receiving feminising hormone treatment and your oestrogen is higher than the desired reference range, or if you are receiving masculinising hormone treatment and your testosterone is higher than the desired reference range, then there are greater risks of adverse health effects. These include increased risks of blood clots, strokes, cardiovascular problems, and organ damage.
Furthermore, hormone levels higher than the desired references are unlikely to speed up feminisation or masculinisation effects, and so will not have any therapeutic benefit. Hence, the dose of oestrogen or testosterone will need to be decreased until the hormone levels are within the reference ranges.
If you are receiving feminising hormone treatment and your oestrogen is lower than the desired reference range, or if you are receiving masculinising hormone treatment and your testosterone is lower than the desired reference range, then feminisation or masculinisation effects may not be achieved as quickly or as effectively as desired. Furthermore, low hormone levels can result in health risks, such as decreased bone density, fatigue, mood instability, and hot flashes. Hence, the dose of oestrogen or testosterone will need to be increased until the hormone levels are within the reference ranges.
If you are receiving feminising hormone treatment and your testosterone is higher than the desired reference range, then this could indicate that your current antiandrogen is not sufficiently effective at suppressing testosterone. Hence, you may continue to experience unwanted masculinising effects. This could indicate a need to change or optimise your antiandrogen medication.
Likewise, if you are receiving masculinising hormone treatment and your oestrogen is higher than the desired reference range, then this could indicate that your current testosterone dose is not sufficiently suppressing oestrogen. Hence, you may continue to experience unwanted feminising effects. This could indicate a need to increase your testosterone dose or to consider adding a hormone blocker.
How are the reference ranges chosen?
As with all reference ranges, the desired reference ranges for oestrogen and testosterone are informed by various factors, including the desired outcome, the optimum levels to achieve desired feminisation or masculinisation effects, safety, and averages from the population.
From an biochemical perspective, the goal of hormone treatment is to achieve levels of oestrogen and testosterone that match the average levels that are typically associated with the person's gender identity. Hence, the desired reference ranges for hormones in feminising hormone treatment closely approximate the typical levels of hormones seen in cis women, while the desired reference ranges for hormones in masculinising hormone treatment closely approximate the typical levels of hormones seen in cis men.
The desired reference ranges also take into account developmental stage. Adolescents who are undergoing puberty tend to have lower levels of oestrogen and testosterone than adults. Furthermore, oestrogen and testosterone levels tend to be lower in early puberty than in late puberty. Hence, the desired reference ranges of oestrogen and testosterone are lower for pubertal adolescents than they are for adults. The reference ranges are also lower for early puberty than they are for late puberty.
For nonbinary people who are aiming for partial feminisation or partial masculinisation at a slower rate, the reference ranges for full feminisation and full masculinisation may not be appropriate. Hence, lower target ranges for oestrogen and testosterone are chosen. These ranges are intended to enable partial feminisation or masculinising effects while also minimising the risks associated with hormone deficiency.
References
- Becker, K. L. (2001). Principles and Practice of Endocrinology and Metabolism. Lippincott Williams and Wilkins.
- Hembree, W. C., Cohen-Kettenis, P. T., Gooren, L., Hannema, S. E., Meyer, W.J, Hassan Murad, M, Rosenthal, S. M., Safer, J. D., Tangpricha, V., and T’Sjoen, G. G. (2017). "Endocrine treatment of gender-dysphoric/gender-incongruent persons: An Endocrine Society Clinical Practice Guideline". Journal of Clinical Endocrinology and Metabolism, 102 (11): 3869–3903.
- World Professional Association of Transgender Health (2022). "Standards of Care for the Health of Transgender and Gender Diverse People, Version 8". International Journal of Transgender Health, 23: S1-S259.
Note: 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. The letter explains why you need blood tests and which ones you'll need to get (read more here: Obtaining Letters and Reports).