Q: Which commonly used diuretic in ICU may effect cosyntropin test?

Answer:  Spironolactone

Patients taking spironolactone or drugs which contain estrogen may exhibit abnormally high basal plasma cortisol levels. Also, women should ideally undergo testing during the first week of their menstrual cycle as aldosterone (and possibly cortisol) may be falsely elevated in the luteal cycle secondary to progesterone inhibition.