ICD-10-CM > S00-T88 > T36-T50 > T50 > T50.Z > T50.Z1 > T50.Z16 T50.Z16 Underdosing of immunoglobulin Non-Billable/Non-Specific Codes T50.Z16A..., initial encounterT50.Z16D..., subsequent encounterT50.Z16S..., sequela