SUN-242 The Utility of Potassium Monitoring in Transgender Adolescents Taking Spironolactone

Background: Spironolactone is an aldosterone antagonist routinely used for its anti-androgenic properties in the treatment of transgender females. Currently available guidelines recommend close monitoring of electrolytes in patients on spironolactone given the risk of hyperkalemia from mineralocorticoid antagonism. However, in otherwise healthy patients taking spironolactone for acne, the rate of hyperkalemia is low, and the utility of frequent monitoring has been called into question. We hypothesized that the rate of significant hyperkalemia in transgender adolescents on spironolactone would likewise be low. Methods: A retrospective chart review of gender diverse youth seen by the Gender Management Service at Boston Children’s Hospital from 2007 to 2017 was performed. Hyperkalemia was defined as a potassium level greater than 5.0 mmol/L. Results: Eighty-eight patients, of whom 85 had a female gender identity and 3 a non-binary identity, with a mean ± SD age of 16.6 ± 1.7 years were prescribed spironolactone for androgen antagonism. Three patients did not have any potassium measurements available and were excluded. The prescribed dose of spironolactone ranged from 25mg/day to 400mg/day, with a mean ± SD dose of 105 ± 43 mg/day. There were mean ± SD of 3.2 ± 1.9 potassium measurements per subject for a total of 269 potassium measurements; 80 prior to spironolactone initiation and 189 while patients were taking spironolactone. There were 8 potassium measurements in 6 subjects that were greater than 5.0 mmol/L. Of these, two measurements in the same subject were noted to by hemolyzed by the laboratory. Excluding these measurements the incidence of mild hyperkalemia was 6%. None of the subjects had symptoms of hyperkalemia, and all hyperkalemic potassium measurements were normal on repeat. Only one subject discontinued spironolactone following an elevated potassium measurement. Spironolactone was restarted following a normal repeat measurement in this subject two weeks later. Repeat measurements were recommended, but never performed. There were no potassium measurements > 6.0 mmol/L. Conclusions: The rate of hyperkalemia in patients taking spironolactone for gender transition is low and when present is transient and asymptomatic. Routine electrolyte monitoring in this population in the absence of other medical comorbidities may be unnecessary.