Fig. 6.

Estimate of correct normal/abnormal flagging using reference intervals (RIs) related to either sex assigned at birth (black boxes) or gender identity (red boxes) for patients either taking estradiol (A) or testosterone (B) as gender-affirming hormones. This analysis assumes that estradiol as gender-affirming therapy does not significantly alter RIs for alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatinine; estradiol does, however, lead to downward shift of hemoglobin RI to essentially match that for cisgender females. The analysis assumes that RIs for ALP, ALT, AST, creatinine, and hemoglobin align with cisgender male RIs for those taking testosterone as gender-affirming hormone. For example, a hemoglobin value of 16.0 g/dL in a transgender man taking testosterone would be above the cisgender female RI but within the cisgender male RI. Use of the sex assigned at birth (female) for RI would lead to incorrect interpretation (hemoglobin concentration too high) compared to using gender identity (male) for the RI (hemoglobin within RI). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)