Researchers in Leipzig are preparing a two-year study of gender-affirming hormone therapy, following changes in metabolism, circulation and other areas of health. By measuring participants before treatment and at regular intervals afterwards, the team hopes to build a clearer picture of what changes, when they happen and what people may need to know during care. [2], [4]

Essential Takeaways

  • A new cohort is planned: Leipzig researchers expect the next phase to begin in early 2027 and follow participants for two years. [4]
  • Repeated measurements matter: Participants are assessed before treatment, then after three, six, 12 and 24 months, allowing researchers to track change within individuals. [2], [4]
  • The study looks beyond hormone levels: Planned measures include body composition, energy use, blood-vessel function and brain imaging. [4]
  • Early findings concern temperature sensing: A small subgroup study found increased sensitivity to warmth and cold among trans women during treatment with oestrogen and a testosterone blocker. [3], [5]
  • The aim is better-informed care: Researchers say stronger evidence could improve information for people considering or receiving hormone therapy. [2], [4]

A closer look at what changes during treatment

Hormone therapy can affect more than the figures on a blood test. A Leipzig research team is preparing a second phase of its Hormones and Health study, following trans participants as they begin gender-affirming treatment and examining how their bodies respond over time. [2], [4]

The focus includes body composition, energy expenditure and the vascular system, alongside questions about blood clotting and metabolism. It is a broad set of measures, reflecting how many systems in the body are influenced by sex hormones. [2], [4]

Why following the same people makes a difference

The first phase followed around 40 trans people who were starting hormone therapy, with trans men and trans women represented in roughly equal numbers. Researchers examined participants before treatment and at several points afterwards, rather than relying only on comparisons between different groups. [2], [4]

That repeated-measure approach can help show how a person's health changes over time. The upcoming phase is expected to follow a new cohort for two years, with checks planned at three, six, 12 and 24 months. [4], [7]

New tools will measure energy, circulation and the brain

The next phase is expected to add a metabolic chamber to measure energy expenditure, as well as more detailed tests of blood-vessel function and blood flow. Researchers also plan to use MRI in collaboration with the Max Planck Institute for Human Cognitive and Brain Sciences to examine brain regions where sex-related differences have previously been reported. [2], [4]

These methods offer a more detailed view than a single blood test can provide. Still, a study design can tell researchers what to investigate, not what the results will be; the new cohort is planned to begin in early 2027. [4]

Early temperature findings are intriguing, not conclusive

One published analysis examined temperature perception in 12 trans women and 17 trans men before treatment, then again after three and six months. Among the trans women, sensitivity to changes in warmth and cold increased during oestrogen treatment alongside a testosterone blocker. [3], [5]

The researchers said the shift was similar in size to a difference previously observed between cis women and cis men. It's an interesting early result, but the subgroup was small, and further research is needed to explain the mechanisms behind the change. [3], [5]

Better evidence could support more informed care

The study's wider purpose is to improve understanding of possible health effects, including changes in metabolism and cardiovascular health. Researchers hope robust evidence will help clinicians explain potential risks and support appropriate care during treatment. [2], [4]

Access to knowledgeable healthcare professionals is another part of the picture. A separate study in northern Germany reported difficulties finding specialist services, including shortages of experienced providers and long journeys in some areas; it did not estimate the scale of any shortage across Germany as a whole. [2], [6]

Good research won't answer every question overnight, but following people carefully over time is a sensible place to start. [2], [4]

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