Z91.138 — Patient's unintentional underdosing of medication regimen for other reason
Z91.138 is a billable, specific ICD-10-CM code for patient's unintentional underdosing of medication regimen for other reason. It is valid for submission on a claim.
Risk adjustment
Z91.138 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
Z91.138 is named in 6 Medicare coverage policies — 6 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A54799Billing and Coding: Urine Drug Testing
- A56645Billing and Coding: Controlled Substance Monitoring and Drugs of Abuse Testing
- A56645Billing and Coding: Controlled Substance Monitoring and Drugs of Abuse Testing
- A56818Billing and Coding: Urine Drug Testing
How Z91.138 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to Z91.138.
- Underdosing›unintentional NEC
- Noncompliance›with›medication regimen NEC›underdosing›unintentional NEC
Related codes at this level
Codes that share Z91.13. If Z91.138 is not quite right, the correct code is usually one of these.
Questions about Z91.138
- Is Z91.138 a billable ICD-10-CM code?
- Yes. Z91.138 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does Z91.138 sit in the tabular list?
- Factors influencing health status and contact with health services (Z00-Z99), in the block Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99).