Adult Transgender Laboratory Testing

Transgender individuals are those who do not identify with the sex they were assigned at birth. This discordance is called gender dysphoria or gender incongruence. A transgender male (previously referred to as female to male [FTM]) is someone who was assigned a female sex at birth but who identifies and lives as a male. A transgender female (previously referred to as male to female [MTF]) is someone who was assigned a male sex at birth but who identifies and lives as a female. Some but not all transgender individuals seek gender-affirming interventions up to and including gender reassignment surgery. The transgender terminology (ie, transgender male, transgender female) applies regardless of treatment or surgery decisions.

Gender affirmation often includes hormone therapy to help realign physical characteristics with gender identity. Laboratory testing plays an important role in establishing a safe and effective hormone regimen. Other medical care, including preventive care screening, should be personalized based on each patient’s unique biology and preferences. Data in this field are limited; much of the information provided below is summarized from the Endocrine Society guideline. For more detailed recommendations, refer to the Endocrine Society clinical practice guideline entitled Endocrine Treatment of Gender-Dysphoric/Gender-Incongruent Persons. 

Quick Answers for Clinicians

Is there a role for laboratory testing in the diagnosis of gender dysphoria/incongruence?

No. A diagnosis of gender dysphoria or gender incongruence is made by an appropriately trained diagnosing clinician and/or mental health provider/professional with specific expertise in this subject.  Laboratory testing is used for monitoring gender affirmation therapy.

Which tests are used to evaluate transgender hormone therapy?

Measurement of testosterone concentrations in the case of transgender males and measurement of testosterone and estradiol concentrations in the case of transgender females should be performed regularly during and after hormone therapy.  Testing by tandem mass spectrometry is more specific and accurate across a wider range of concentrations; this method is preferable if low concentrations are expected. Testing by immunoassay is accurate only at higher concentrations. Patients should also be monitored for certain other secondary health risks, such as metabolic and electrolyte imbalances. 

Which reference intervals should be used for transgender individuals?

The goals of gender-affirming hormone therapy are typically to suppress endogenous sex steroids and maintain exogenous sex steroids within the normal physiologic range for the target gender.  Reference ranges specific for transgender patients have not been established. In many cases, the applicable reference intervals for the target gender may provide an initial target goal, but results should be interpreted with caution.

Monitoring of Treatment

Youth and Adolescents

Puberty-blocking and gender-affirming hormone treatment is discouraged in prepubertal youth.  Adolescents undergoing suppression or induction of puberty should be cared for by an expert multidisciplinary team that includes medical and mental health professionals; such patients should also receive regular clinical and laboratory monitoring.  Due to the paucity of data to direct treatment management for youth and adolescents and the controversy among professionals, this ARUP Consult topic focuses on laboratory testing and care for transgender adults. For treatment recommendations for adolescents, refer to the Endocrine Society Clinical Practice Guideline.  The University of California, San Francisco  also offers guidance for gender-nonconforming children and transgender adolescents.

Adult Transgender Males

Hormone Testing

Serum testosterone concentrations should be measured every 3 months until levels fall within the normal reference range for a cisgender (physiologic) male.  Timing of measurements depends on the type of therapy :

  • For testosterone enanthate/cypionate injections, the target level is 400-700 ng/dL; measurements can be taken either midway between injections or at peak and trough levels.
  • For parenteral testosterone undecanoate, the dose interval should be increased if testosterone levels are <400 ng/dL; measurements should be taken right before the next injection (ie, at trough levels).
  • For transdermal testosterone, measurements should be taken no sooner than after 1 week of daily application and at least 2 hours after application.

Testing can be performed using either tandem mass spectrometry or electrochemiluminescent immunoassay. Tandem mass spectrometry is more specific and accurate across a wider range of concentrations and is preferable if low concentrations are expected. Testing by immunoassay is accurate at higher concentrations.

Other Testing

In addition to serum hormone measurements, the following tests or assessments should be performed :

  • Clinical assessment of feminization and monitoring for adverse reactions should be performed every 3 months in the first year, then once or twice yearly.
  • Serum electrolyte levels (particularly potassium levels) should be monitored every 3 months, then annually in individuals on spironolactone.
  • Prolactin concentrations should be monitored periodically in transgender females treated with estrogens.

Albumin and/or sex hormone-binding globulin (SHBG) measurements can be used to calculate the level of bioavailable testosterone.  Bioavailable testosterone levels may be a better indicator of hormone effect than total testosterone measurements in patients with binding protein levels that are much higher or lower than expected. Although this testing is optional, it may be of value for patients with unexpected responses to hormone therapy. 

Preventive Care Screening

As part of treatment monitoring, preventive screenings are recommended for applicable health risks :

  • Osteoporosis screening should be performed in individuals who stop testosterone treatment, do not comply with therapy, or develop risk for bone loss.
  • Cervical cancer screening, if cervical tissue is present, should be performed according to the American College of Obstetricians and Gynecologists recommendations. 
  • Breast examinations (sub- and periareolar) should be performed annually in individuals who have had a mastectomy; mammograms should be considered according to American Cancer Society guidelines for individuals who have not had mastectomy.
  • Cardiovascular disease risk should be assessed in transgender persons treated with hormones.

Adult Transgender Females

Hormone Testing

Serum testosterone and serum estradiol concentrations should be measured every 3 months.  Serum testosterone levels should be <50 ng/dL; serum estradiol levels should not exceed the peak physiologic range of 100-200 pg/mL. 

Testing can be performed using either tandem mass spectrometry or electrochemiluminescent immunoassay. Tandem mass spectrometry is more specific and accurate across a wider range of concentrations and is preferable if low concentrations are expected. Testing by immunoassay is accurate at higher concentrations.

Other Testing

In addition to serum hormone measurements, the following tests or assessments should be performed :

  • Clinical assessment of feminization and monitoring for adverse reactions should be performed every 3 months in the first year, then once or twice yearly.
  • Serum electrolyte levels (particularly potassium levels) should be monitored every 3 months, then annually in individuals on spironolactone.
  • Prolactin concentrations should be monitored periodically in transgender females treated with estrogens.

Albumin and/or SHBG measurements can be used to calculate the level of bioavailable testosterone.  Bioavailable testosterone levels may be a better indicator of hormone effect than total testosterone measurements in patients with binding protein levels that are much higher or lower than expected. Although this testing is optional, it may be of value for patients with unexpected responses to hormone therapy. 

Preventive Care Screening

As part of treatment monitoring, screenings are recommended for applicable health risks :

  • Osteoporosis screening should be performed in patients at low risk at 60 years or in patients who do not comply with therapy; a baseline bone mineral density test should be considered before starting treatment.
  • Routine cancer screening should be performed for all tissues present; transgender females treated with estrogens should follow general guidelines for breast cancer screening and screening according to individual risk for prostatic disease and prostate cancer.
  • Cardiovascular disease risk should be assessed in transgender persons treated with hormones.

ARUP Laboratory Tests

Total Testosterone Tests

Appropriate for measuring a wide range of concentrations, and especially useful if low concentrations are expected, regardless of the patient’s sex assigned at birth

Recommended when high concentrations are expected, regardless of the patient’s sex assigned at birth; not recommended when low concentrations, such as those found in cisgender women and children, are expected

Total Estradiol Tests

Appropriate for measuring a wide range of concentrations, and especially useful if low concentrations are expected, regardless of the patient’s sex assigned at birth

Recommended when high concentrations are expected, regardless of the patient’s sex assigned at birth; not recommended when low concentrations, such as those found in cisgender men, are expected

Related Tests

May be useful to calculate bioavailable testosterone

Monitor effects of hormone therapy

AlertOther tests that measure free and bioavailable testosterone are available at aruplab.com.

Medical Experts

Contributor

Kroner

 
Grace M. Kroner, PhD
Clinical Chemistry Fellow at ARUP Laboratories and University of Utah
Contributor

References

Additional Resources
Resources from the ARUP Institute for Clinical and Experimental Pathology®