Transgender Analysis of Nephrological Studies Focused on Renal Metrics (TRANSFORM)

April 17, 2026 updated by: Daniel van Raalte, Amsterdam UMC, location VUmc
This study investigates how sex hormones affect kidney function in people undergoing gender-affirming hormone therapy (GAHT). We know men have a faster progression of kidney disease. Earlier studies suggest that the female sex hormone estradiol may have a protective effect on kidney function while the male sex hormone testosterone may have the opposite effect. But the reasons why this happens remain unclear. By studying participants undergoing (GAHT) we gain insight into the mechanisms by which testosterone and estradiol influence the kidneys. People undergoing GAHT provide a unique chance to study how sex hormones interact with the kidneys. The results may help us to understand why men and women exhibit differences in kidney disease development. This study will include 30 men and 30 women, aged 18 to 40, who start GAHT. Participants will have three study visits, two of which will happen during their scheduled healthcare appointments. During the first visit, a screening will take place to check if patients can take part in the study. At study visits before and after one year of therapy, kidney function is measured, kidney MRI is performed, urine is collected and a small sample of fat tissue. Taking part in the study does not delay the start of GAHT.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Sex differences in kidney physiology are a vastly understudied area, despite known differences in sex-specific rates of chronic kidney disease. Kidney function decline is accelerated in men compared to women, suggesting a potential harmful role for testosterone. Transgender individuals undergoing hormone therapy provide a unique model to study the effects of gender affirming hormone therapy on kidney function and renal physiology. The central objectives of this study are to comprehensively assess the effects of gender affirming hormone therapy (GAHT; testosterone in transgender men or estradiol and an anti-androgen in transgender women) therapy on kidney function and physiology. This study is a prospective observational study. In total we will include 60 transgender individuals (30 transgender men and 30 transgender women) between 18-40 years old, scheduled to start GAHT. The primary endpoint is measured glomerular filtration rate (GFR) by iohexol clearance. Secondary endpoints include effects of GAHT on measures of intrarenal hemodynamic function including effective renal plasma flow (ERPF), proximal tubular function, insulin sensitivity and multiparametric kidney MRI (phase-contrast MRI [perfusion], arterial spin labeling [perfusion], BOLD imaging with a multi-echo spin-echo mapping R2* [oxygenation] and diffusion-weighted MRI [diffusion]). We will also isolate urinary tubuloids to further study the effect of sex hormones on kidney physiology and in these tubuloids we will assess whether the kidney protective effects are affected by sex hormones in vitro. Furthermore, endothelial cells will be harvested by J-wire, and single-cell RNA sequencing will be performed to investigate the transcriptional effects of GAHT in endothelial cells. And finally, we will look at adipose tissue gene expression.The burden for participants consists of three study visits, two of which will replace scheduled meetings that are a part of standard healthcare practice. In total, participants will receive one venipuncture and four intravenous cannulas, from which blood will be sampled (study total of 275 mL) and iohexol and p-aminohippurate will be administered to measure GFR and ERPF respectively. After measurement of kidney function, insulin sensitivity will be measured using a variable infusion of glucose and insulin (hyperinsulinemic euglycemic clamp). Patients will undergo kidney MRI which will take about 45 minutes; participants with claustrophobia are excluded. In addition, participants will be asked to collect a 24-hour urine sample on the days prior to the second and third study visit. Subcutaneous adipose tissue is collected by needle aspiration after local anesthesia. Finally, endothelial cells will be harvested. The total risk of negative effects for participants in the current study is considered low. The transgender population is a unique population in which the effects of exogenous cross-sex hormone administration can be studied. This study may provide additional data on the safety of hormone therapy in this population and may also lead to meaningful insights regarding the physiological effects of sex hormones on kidney function in humans that may help to understand observations from cohort studies which indicate differences in progression to kidney failure dependent on gender.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Netherlands
    • North Holland
      • Amsterdam, North Holland, Netherlands
        • Amsterdam UMC, location VU medical centre, internal medicine
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

The source population consists of adult patients with gender dysphoria, who are scheduled to start with GAHT in the Amsterdam University Medical Centre (AUMC) in Amsterdam. A total of 60 transgender individuals (30 transgender women, 30 transgender men) will be selected from this outpatient clinic.

Description

Inclusion Criteria:

  • Diagnosed with gender dysphoria according to DSM-V
  • Expected to start gender-affirming hormone treatment in the upcoming month

Exclusion Criteria:

  • Current or prior use of gender-affirming hormone therapy
  • Participation in other studies
  • Concomitant use of medication (specifically: antihypertensive agents, products, antidepressants, antipsychotic agents)
  • Known kidney disease (eGFR < 60 ml/min; UACR > 2.5 mg/mmol)
  • Diabetes mellitus
  • A history of cardiovascular disease (myocardial infarction; cardiac surgery or revascularization, unstable angina, heart failure, transient ischemic attack, cerebrovascular disease, or a previously undiagnosed arrhythmia)
  • Known iodine-related allergies
  • Metal in the body (such as pacemaker, ICD, neurostimulator, cochlear implant, or other metal)
  • Pregnancy
  • Claustrophobia

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Transgender males
Individuals clinically scheduled to start GAHT with testosterone therapy
Diagnostic test: P-aminohippurate clearance study
To measure effective renal plasma flow (ERPF), small doses of a substance called p-aminohippurate will be used
Diagnostic test: Iohexol infusion
To measure glomerular filtration rate (GFR) iohexol clearance will be performed
Diagnostic test: Hyperinsulinemic clamp
Glucose/insulin infusion to measure insulin sensitivity
Transgender women
Individuals clinically scheduled to start GAHT with estradiol and anti-androgen therapy
Diagnostic test: P-aminohippurate clearance study
To measure effective renal plasma flow (ERPF), small doses of a substance called p-aminohippurate will be used
Diagnostic test: Iohexol infusion
To measure glomerular filtration rate (GFR) iohexol clearance will be performed
Diagnostic test: Hyperinsulinemic clamp
Glucose/insulin infusion to measure insulin sensitivity

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Change in measured glomerular filtration rate (GFR)
Time Frame: Baseline, 12 months after start GAHT
Baseline, 12 months after start GAHT

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in effective renal plasma flow (ERPF)
Time Frame: Baseline, 12 months after start GAHT
Baseline, 12 months after start GAHT
Change in systemic hemodynamic function
Time Frame: Baseline, 12 months after start GAHT
Baseline, 12 months after start GAHT
Change in insulin sensitivity
Time Frame: Baseline, 12 months after start GAHT
Baseline, 12 months after start GAHT
Change in markers of tubular physiology
Time Frame: Baseline, 12 months after start GAHT
Baseline, 12 months after start GAHT
Changes in multiparametric kidney MRI
Time Frame: Baseline, 12 months after start GAHT
Including (phase-contrast MRI (perfusion), arterial spin labeling (perfusion), BOLD imaging with multi-echo spin-echo mapping R2* (oxygenation) and diffusion-weighted (DW) MRI (diffusion)
Baseline, 12 months after start GAHT
Changes in endothelial function
Time Frame: Baseline, 12 months after start GAHT
Baseline, 12 months after start GAHT
Change in adipose tissue gene expression and adipose tissue biology
Time Frame: Baseline, 12 months after start GAHT
Baseline, 12 months after start GAHT
Change in tubular effects of kidney protective therapies in vitro
Time Frame: Baseline, 12 months after start GAHT
Baseline, 12 months after start GAHT

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Amsterdam UMC, location VUmc

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Dutch Kidney Foundation

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 10, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 17, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 21, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 21, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 17, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • NL-011071

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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