Z51.81
Billable codeEncounter for therapeutic drug level monitoring
The ICD-10 code for encounter for therapeutic drug level monitoring is Z51.81.
Clinical notes
Code also
Two codes may be needed to fully describe a condition, but unlike Code First/Use Additional Code, the sequencing order is not mandated by convention.
- any long-term (current) drug therapy (Z79.-)
Excludes1 (not coded here)
An Excludes1 note is a pure exclusion: the excluded condition and this code should never be reported together, because the two conditions cannot occur at the same time (e.g. a congenital form vs. an acquired form of the same disease).
- encounter for blood-drug test for administrative or medicolegal reasons (Z02.83)
Documentation support
General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.
- •Confirm the excluded condition(s) listed above are not also present — Excludes1 conditions cannot be coded together with this one.
- •As a general rule, code to the highest level of specificity supported by the documentation in the medical record.
Related codes in this category
- Z51.89Encounter for other specified aftercare
- Z51.81Encounter for therapeutic drug level monitoring
ICD-9-CM equivalent
Informational only — GEM mappings are approximate, not guaranteed one-to-one equivalents. Verify before use in billing.
- V5883
Associated MS-DRGs
Z51.81 can serve as the principal diagnosis for these Medicare Severity Diagnosis-Related Groups.
Informational only — actual DRG assignment also depends on procedures, complications/comorbidities (CC/MCC), discharge status, and payer-specific rules not reflected here.