April 19, 2021 -- Transgender people treated with gender-affirming hormone therapy show distinctive changes in blood pressure that begin soon after treatment starts and do not ease over years of treatment, according to the largest and longest observational study to look at the issue.
"Many physicians may not be aware of the changes to blood pressure in trans patients who start hormone therapy," senior author Michael S. Irwig, MD, director of transgender medicine at Beth Israel Deaconess Medical Center in Boston, told Medscape.
"The take-away message for physicians is to monitor blood pressure both before and after starting hormone therapy in transgender patients, as over a third of transgender individuals had stage 1 hypertension before starting hormone therapy, and many had their blood pressure increase after starting hormone therapy."
Increases in Transgender Males, Decreases in Females
In the study,published this week in the journal Hypertension, Katherine Banks, MD, of the George Washington School of Medicine & Health Sciences in Washington, D.C., and colleagues, followed 470 transgender adult patients for up to 5 years.
The average systolic blood pressure levels (the top number of a reading) in transgender females significantly decreased within a few months of starting gender-affirming hormone treatment.
Conversely, the systolic blood pressure levels in transgender males who were treated with testosterone increased over the same period.
There were no significant changes in the groups in terms of diastolic blood pressure, the second number in a reading, similar to other studies.
Gender-affirming hormone therapy — which has been prescribed to transgender patients for more than 25 years — typically involves a combination of estrogen and an testosterone blocks for males transitioning to female, while the therapy for those transitioning to male generally only involves testosterone.
Although the American Heart Association issued a 2020 Scientific Statement addressing the heart disease risk, evidence on the effects specifically on blood pressure in transgender patients has been inconsistent.
For the new study, Banks and colleagues enrolled 247 transgender females and 223 transgender males who were treated between 2007 and 2015 at two medical centers in Washington. Of the patients, who had an average age of 27.8, about 27% were non-White and 16% were Latino.
They had blood pressure measurements taken at the beginning of the study and at follow-up visits for up to 57 months after the start of gender-affirming hormone therapy.
As many as 40% of transgender men had stage 1 hypertension after 11 to 21 months of hormone therapy.
The blood pressure changes in transgender males and females were observed across all racial ethnic groups and the changes remained consistent throughout the entire follow-up period of nearly 5 years
More than one third of individuals in both groups had stage 1 hypertension before starting hormone therapy.
The findings are a concern in light of "clear evidence linking hypertension and higher blood pressure with cardiovascular events such as stroke and heart attacks," Irwig said.
Protective Effects for Transgender Females?
Transgender females showed as much as a 47% decrease in the rate of stage 2 hypertension and the rate declined further to 8% at 11 to 21 months, suggesting a protective effect of the treatment.
"This was not a surprise, as lowering testosterone and the use of spironolactone (a diuretic) can lower blood pressure," he noted.