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D74.9 ICD-10-CM Code: Methemoglobinemia, unspecified

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 811 — RED BLOOD CELL DISORDERS WITH MCC (MDC 16)
  • MS-DRG 812 — RED BLOOD CELL DISORDERS WITHOUT MCC (MDC 16)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coder workflow for D74.9

MedCoder structured workflow — derived from this code’s own official record

Before you code D74.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, D74.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewD74.0, D74.8

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — D74.9 is appropriate when the documentation goes no further.

    ReviewD74.0, D74.8

Consider D74.9. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewD74.0, D74.8

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Methemoglobinemia, unspecified is a billable ICD-10-CM diagnosis code (D74.9).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (1)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Official Coding Guidelines

No excerpt in the ICD-10-CM Official Guidelines names this code specifically. Its chapter carries only this chapter-wide note:

Chapter 3: Disease of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89)

Reserved for future guideline expansion

Verify Before Coding

  • CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name D74.9 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: D58.2 — Other hemoglobinopathies (via D74.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 21 Code First instructions: T36 — Poisoning by, adverse effect of and underdosing of systemic antibiotics (via D74.-), T36-T39 — Antibiotics & Anti-infectives (T36-T39) (via D74.-), T36-T50 — Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50) (via D74.-), T37 — Poisoning by, adverse effect of and underdosing of other systemic anti-infectives and antiparasitics (via D74.-), T38 — Poisoning by, adverse effect of and underdosing of hormones and their synthetic substitutes and antagonists, not elsewhere classified (via D74.-), T39 — Poisoning by, adverse effect of and underdosing of nonopioid analgesics, antipyretics and antirheumatics (via D74.-), T40 — Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens] (via D74.-), T40-T41 — Analgesics & Antipyretics (T40-T41) (via D74.-), T41 — Poisoning by, adverse effect of and underdosing of anesthetics and therapeutic gases (via D74.-), T42 — Poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs (via D74.-), T42-T43 — Anticonvulsants & Psychotropics (T42-T43) (via D74.-), T43 — Poisoning by, adverse effect of and underdosing of psychotropic drugs, not elsewhere classified (via D74.-), T44 — Poisoning by, adverse effect of and underdosing of drugs primarily affecting the autonomic nervous system (via D74.-), T44-T46 — Cardiovascular & Gastrointestinal (T44-T46) (via D74.-), T45 — Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified (via D74.-), T46 — Poisoning by, adverse effect of and underdosing of agents primarily affecting the cardiovascular system (via D74.-), T47 — Poisoning by, adverse effect of and underdosing of agents primarily affecting the gastrointestinal system (via D74.-), T47-T50 — Hormones & Systemic Agents (T47-T50) (via D74.-), T48 — Poisoning by, adverse effect of and underdosing of agents primarily acting on smooth and skeletal muscles and the respiratory system (via D74.-), T49 — Poisoning by, adverse effect of and underdosing of topical agents primarily affecting skin and mucous membrane and by ophthalmological, otorhinorlaryngological and dental drugs (via D74.-), +1 more.

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 24 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 811 (MDC 16), DRG 812 (MDC 16).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):BLD010 — Other specified and unspecified hematologic conditions (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

D58.9 — Hereditary hemolytic anemia, unspecified, D59.0 — Drug-induced autoimmune hemolytic anemia, D59.10 — Autoimmune hemolytic anemia, unspecified, D59.11 — Warm autoimmune hemolytic anemia, D59.12 — Cold autoimmune hemolytic anemia, D59.13 — Mixed type autoimmune hemolytic anemia, D59.19 — Other autoimmune hemolytic anemia, D59.2 — Drug-induced nonautoimmune hemolytic anemia, D59.4 — Other nonautoimmune hemolytic anemias, D59.5 — Paroxysmal nocturnal hemoglobinuria [Marchiafava-Micheli], D59.6 — Hemoglobinuria due to hemolysis from other external causes, D59.8 — Other acquired hemolytic anemias, D59.9 — Acquired hemolytic anemia, unspecified, D64.4 — Congenital dyserythropoietic anemia, D64.81 — Anemia due to antineoplastic chemotherapy, D64.89 — Other specified anemias, D64.9 — Anemia, unspecified, D74.0 — Congenital methemoglobinemia, D74.8 — Other methemoglobinemias, D75.9 — Disease of blood and blood-forming organs, unspecified, +3 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other specified and unspecified hematologic conditions).

A18.85 — Tuberculosis of spleen, B51.0 — Plasmodium vivax malaria with rupture of spleen, D73.0 — Hyposplenism, D73.1 — Hypersplenism, D73.2 — Chronic congestive splenomegaly, D73.3 — Abscess of spleen, D73.4 — Cyst of spleen, D73.5 — Infarction of spleen, D73.89 — Other diseases of spleen, D73.9 — Disease of spleen, unspecified, D74.0 — Congenital methemoglobinemia, D74.8 — Other methemoglobinemias, D75.0 — Familial erythrocytosis, D75.1 — Secondary polycythemia, D75.81 — Myelofibrosis, D75.89 — Other specified diseases of blood and blood-forming organs, D75.9 — Disease of blood and blood-forming organs, unspecified, D75.A — Glucose-6-phosphate dehydrogenase (G6PD) deficiency without anemia, D77 — Other disorders of blood and blood-forming organs in diseases classified elsewhere, M36.3 — Arthropathy in other blood disorders

Contextual Map

Every relationship of D74.9 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run D74.9 with these 9 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Code First instructions (21)

Clinical classification (CCSR)

MS-DRG Grouper

  • CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
  • DRG 811 — RED BLOOD CELL DISORDERS WITH MCC[MS-DRG]: “RED BLOOD CELL DISORDERS WITH MCC (MDC 16)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
  • DRG 812 — RED BLOOD CELL DISORDERS WITHOUT MCC[MS-DRG]: “RED BLOOD CELL DISORDERS WITHOUT MCC (MDC 16)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

  • MDC 16 — Diseases and Disorders of Blood, Blood Forming Organs and Immunologic Disorders[MDC crossing]: “Diseases and Disorders of Blood, Blood Forming Organs and Immunologic Disorders — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1,614 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

  • Methemoglobinemia[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "D74.9 — Methemoglobinemia, unspecified." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/d74.9-methemoglobinemia-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Methemoglobinemia, unspecified

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to D74.9 in its code family, with their registry titles.

View all codes in the D74 family