ICD-10-CM > S00-T88 > T36-T50 > T46 > T46.4 > T46.4X > T46.4X6 T46.4X6 Underdosing of angiotensin-converting-enzyme inhibitors Non-Billable/Non-Specific Codes T46.4X6A..., initial encounterT46.4X6D..., subsequent encounterT46.4X6S..., sequela