Study investigators quantified the variability in kidney function estimates between three commonly used equations when applied to a population of 258 transgender participants enrolled in a PrEP demonstration project (parent study: ImPrEPT, NCT03086200).  Primary outcome was estimated renal function based on the Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations.  Two iterations of calculations were performed, the first using sex assigned at birth and the second gender identity.  Authors observed a median difference of +16 (-11 to +21) mL/min in estimated CL_CR when using sex assigned at birth for the gender coefficient vs. gender identity.  Median differences in eGFR when using sex assigned at birth vs. gender identity were +25 (-19 to +33) mL/min and +13 (-10 to +22) mL/min, respectively, for GFR_MDRD and GFR_CKD-EPI.  Among male sex assigned at birth individuals, significantly higher median renal function estimates were observed among users of gender-affirming therapy than nonusers (this observation was consistent regardless of method or equation used).  Conversely, renal function estimates were lower for female sex assigned at birth users of gender-affirming therapy compared with nonusers.  Overall, 6.6% of participants would have been potentially rendered ineligible for TDF/FTC-based PrEP based on at least one of the equations/methods yielding a creatinine clearance value < 60 mL/min (the proportion varied by equation and gender coefficient used).