Hematocrit Levels: What We Can Learn From Transgender Studies

[CoastWatcher]

One of the most frequent, unwanted side-effects for men on TRT is the rise in hematocrit levels. A recent study of trans men highlighted the issue.

• In trans persons on gender-affirming hormonal treatment, a decrease (in trans women) or increase (in trans men) in hematocrit is often observed.
• 625 hormone-naïve trans persons were enrolled in the study.
• Gender-affirming hormonal treatment was initiated at the first visit.
• In trans men, serum hematocrit (Hct) levels increased during the first year (+4.9 Hct %, 95% CI 3.82-5.25), with the most pronounced increase during the first 3 months (+2.7 Hct %, 95% CI 1.94-3.29).
• Trans men receiving testosterone esters had a larger increase in serum hematocrit levels compared to trans men receiving testosterone undecanoate (Δ 0.8 Hct %). Of 192 trans men, 22 (11.5%) developed serum hematocrit levels ≥50.0%.
• Trans men on testosterone undecanoate were less likely to develop hematocrit levels ≥50% or ≥52%, compared to trans men on testosterone esters, and were less likely to develop hematocrit levels ≥50%, compared to trans men on testosterone gel.
• In trans women, serum hematocrit had dropped by 4.1 Hct % (95% CI 3.50-4.37) after 3 months, after which only small decreases were observed. In conclusion, serum hematocrit levels can be found in the reference range of the perceived gender as from 3 months after the initiation of gender-affirming hormonal treatment.

"Prospective evaluation of hematocrit in gender-affirming hormone treatment: results from European Network for the Investigation of Gender Incongruence." Andrology, 30 March 2018, https://www.ncbi.nlm.nih.gov/pubmed/29602229/