2026 ICD-10-CM Diagnosis Code R78.9Finding of unspecified substance, not normally found in blood

ICD-10-CM Codes›R00–R99›R70-R79›R78

ICD-10-CM R78.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R78.9 is a billable ICD-10-CM diagnosis code for finding of unspecified substance, not normally found in blood. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 947 through 948. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. Coders also document this condition as medication serum levels outside of reference range. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Abnormal findings without diagnosis.

Code Identity

ICD-10-CM Code
R78.9
Billable Status
Yes — Valid for Submission
Code Describes
Finding of unspecified substance, not normally found in blood
Short Description
Finding of unsp substance, not normally found in blood
Parent Code
R78
Findings of drugs and other substances, not normally found in blood

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR70-R79Abnormal findings on examination of blood, without diagnosis
CategoryR78Findings of drugs and other substances, not normally found in blood
This CodeR78.9Finding of unspecified substance, not normally found in blood

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Medication serum levels outside of reference range

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Abnormal, abnormality, abnormalities
      • toxicology (findings)
    • Blood
      • constituents, abnormal
    • Findings, abnormal, inconclusive, without diagnosis
      • in blood (of substance not normally found in blood)

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR SYM017
Abnormal findings without diagnosis
Default principal diagnosis: inpatient Yes · outpatient Yes

Convert R78.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
790.99 Oth nspcf finding blood
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About R78.9Overview

Is R78.9 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report finding of unspecified substance, not normally found in blood on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does R78.9 group to?

When finding of unspecified substance, not normally found in blood is the principal diagnosis on an inpatient stay, it groups to MS-DRG 947, 948, with relative weights from 0.8005 to 1.2694 depending on complications. Higher weights mean higher Medicare reimbursement.

Can R78.9 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the finding of unspecified substance, not normally found in blood is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R78.9?

Under the General Equivalence Mappings, finding of unspecified substance, not normally found in blood converts to ICD-9-CM 790.99 (oth nspcf finding blood). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.