Prospective evaluation of hematocrit in gender‐affirming hormone treatment: results from European Network for the Investigation of Gender Incongruence

Abstract

In trans persons on gender-affirming hormonal treatment, a decrease (in trans women) or increase (in trans men) in hematocrit is often observed. Reference ranges for evaluation of hematocrit levels in trans persons have not been established. This prospective cohort study is part of the European Network for the Investigation of Gender Incongruence (ENIGI). At the Ghent and Amsterdam sites, we included 625 hormone-naïve trans persons. 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.

Studies of athlete biological passport biomarkers and clinical parameters in male and female users of anabolic androgenic steroids and other doping agents

“…This gender difference could simply be due to the lower AAS doses used by women. However, when supra‐physiological doses of testosterone were given to transgender men, hematocrits higher than 50% were rarely found . Thus, hematological biomarkers for AAS use may be restricted to men using AAS.…”

Testosterone undecanoate and testosterone enanthate injections are both effective and safe in transmen over 5 years of administration

“…Both T formulations similarly led to an increase in haemoglobin and haematocrit although this always remained within the physiological range. It has been recently reported that transmen receiving TE had higher increases in serum haematocrit levels compared to transmen receiving TU and an explanation might be that short‐acting intramuscular injections cause a rapid supraphysiological peak shortly after injection . It is well known that androgens stimulate erythropoiesis .…”

“…In the hypogonadal men, TU has been associated with rare cases of pulmonary oil microembolism (1.5 per 10 000 injections) . TE, on the other hand, requires frequent injections resulting in peaks and troughs in T levels that may have consequences on mood and various health parameters, in particular on the rate of erythrocytosis which is higher in subjects receiving short‐acting intramuscular injections . We reported that in the short term—1 year—short and long‐acting T formulations perform equally in terms of efficacy and safety in transmen subjects .…”

Transgender patients and the role of the coagulation clinician

“…In a prospective study of transmen initiating hormone therapy, the hematocrit increased over the first 12 months of testosterone use, with the largest increase in the first 3 months. 57 Only 11.5% of transmen were found to have an increased hematocrit >50%, with a maximal hematocrit of 54% seen in 1 of 192 testosterone-treated patients. Increased BMI was associated with a hematocrit >50%; no differences in smoking or other risk factors were seen.…”

“…Erythrocytosis is expected with the use of testosterone in transmen but a possible increase in thromboembolic risk is concerning. In a prospective study of transmen initiating hormone therapy, the hematocrit increased over the first 12 months of testosterone use, with the largest increase in the first 3 months . Only 11.5% of transmen were found to have an increased hematocrit >50%, with a maximal hematocrit of 54% seen in 1 of 192 testosterone‐treated patients.…”