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D66 ICD-10-CM Code: Hereditary factor VIII deficiency

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

Coding at a Glance

Tabular directives
4 inclusion terms · 1 Excludes1
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 46

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.

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.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 111 — Hemophilia, Male (supersedes HCC 112)

Other models: CMS-HCC V22 HCC 46

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for D66 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Classical hemophilia
  • Deficiency factor VIII (with functional defect)
  • Hemophilia NOS
  • Hemophilia A

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Coder workflow for D66

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

Before you code D66

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with D66. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in D66’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewD68.0

Consider D66. 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).

Official instructions as workflow

  • Excludes1 — check before selecting D66(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with D66: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareD68.0

    See the official tabular notes · Guidelines I.A.12.a

Coding decision scenarios

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

Documentation: Both the condition D66 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewD68.0

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

Hereditary factor VIII deficiency is a billable ICD-10-CM diagnosis code (D66).

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 (11)

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

  • MCC 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 D66 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: D68.0 — Von Willebrand disease.

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

Referenced by 10 Excludes2 notes: R70 — Elevated erythrocyte sedimentation rate and abnormality of plasma viscosity, R70-R79 — Abnormal findings on examination of blood, without diagnosis (R70-R79), R71 — Abnormality of red blood cells, R73 — Elevated blood glucose level, R74 — Abnormal serum enzyme levels, R75 — Inconclusive laboratory evidence of human immunodeficiency virus [HIV], R76 — Other abnormal immunological findings in serum, R77 — Other abnormalities of plasma proteins, R78 — Findings of drugs and other substances, not normally found in blood, R79 — Other abnormal findings of blood chemistry.

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 22 Code First instructions across 2 chapters: M36.2 — Hemophilic arthropathy, T36 — Poisoning by, adverse effect of and underdosing of systemic antibiotics, T36-T39 — Antibiotics & Anti-infectives (T36-T39), T36-T50 — Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50), T37 — Poisoning by, adverse effect of and underdosing of other systemic anti-infectives and antiparasitics, T38 — Poisoning by, adverse effect of and underdosing of hormones and their synthetic substitutes and antagonists, not elsewhere classified, T39 — Poisoning by, adverse effect of and underdosing of nonopioid analgesics, antipyretics and antirheumatics, T40 — Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens], T40-T41 — Analgesics & Antipyretics (T40-T41), T41 — Poisoning by, adverse effect of and underdosing of anesthetics and therapeutic gases, T42 — Poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs, T42-T43 — Anticonvulsants & Psychotropics (T42-T43), T43 — Poisoning by, adverse effect of and underdosing of psychotropic drugs, not elsewhere classified, T44 — Poisoning by, adverse effect of and underdosing of drugs primarily affecting the autonomic nervous system, T44-T46 — Cardiovascular & Gastrointestinal (T44-T46), T45 — Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified, T46 — Poisoning by, adverse effect of and underdosing of agents primarily affecting the cardiovascular system, T47 — Poisoning by, adverse effect of and underdosing of agents primarily affecting the gastrointestinal system, T47-T50 — Hormones & Systemic Agents (T47-T50), T48 — Poisoning by, adverse effect of and underdosing of agents primarily acting on smooth and skeletal muscles and the respiratory system, +2 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: MCC — Major 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 50 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 1 MS-DRG: DRG 813 (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):BLD006 — Coagulation and hemorrhagic disorders (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 MCC — 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.

D47.4 — Osteomyelofibrosis, D65 — Disseminated intravascular coagulation [defibrination syndrome], D67 — Hereditary factor IX deficiency, D68.00 — Von Willebrand disease, unspecified, D68.01 — Von Willebrand disease, type 1, D68.020 — Von Willebrand disease, type 2A, D68.021 — Von Willebrand disease, type 2B, D68.022 — Von Willebrand disease, type 2M, D68.023 — Von Willebrand disease, type 2N, D68.029 — Von Willebrand disease, type 2, unspecified, D68.03 — Von Willebrand disease, type 3, D68.04 — Acquired von Willebrand disease, D68.09 — Other von Willebrand disease, D68.1 — Hereditary factor XI deficiency, D68.2 — Hereditary deficiency of other clotting factors, D68.311 — Acquired hemophilia, D68.312 — Antiphospholipid antibody with hemorrhagic disorder, D68.318 — Other hemorrhagic disorder due to intrinsic circulating anticoagulants, antibodies, or inhibitors, D68.32 — Hemorrhagic disorder due to extrinsic circulating anticoagulants, D68.4 — Acquired coagulation factor deficiency, +29 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Hemophilia, Male) for risk-adjusted payment.

D67 — Hereditary factor IX deficiency

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Immune Thrombocytopenia and Specified Coagulation Defects and Hemorrhagic Conditions

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Coagulation and hemorrhagic disorders).

D47.3 — Essential (hemorrhagic) thrombocythemia, D65 — Disseminated intravascular coagulation [defibrination syndrome], D67 — Hereditary factor IX deficiency, D68.0 — Von Willebrand disease, D68.00 — Von Willebrand disease, unspecified, D68.01 — Von Willebrand disease, type 1, D68.020 — Von Willebrand disease, type 2A, D68.021 — Von Willebrand disease, type 2B, D68.022 — Von Willebrand disease, type 2M, D68.023 — Von Willebrand disease, type 2N, D68.029 — Von Willebrand disease, type 2, unspecified, D68.03 — Von Willebrand disease, type 3, D68.04 — Acquired von Willebrand disease, D68.09 — Other von Willebrand disease, D68.1 — Hereditary factor XI deficiency, D68.2 — Hereditary deficiency of other clotting factors, D68.311 — Acquired hemophilia, D68.312 — Antiphospholipid antibody with hemorrhagic disorder, D68.318 — Other hemorrhagic disorder due to intrinsic circulating anticoagulants, antibodies, or inhibitors, D68.32 — Hemorrhagic disorder due to extrinsic circulating anticoagulants, +31 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Hemophilia”, “Deficiency, deficient”, “Arthritis, arthritic”, …; these codes share that main term but sit in a different category of the Tabular List.

D50.9 — Iron deficiency anemia, unspecified (iron, anemia), D51.0 — Vitamin B12 deficiency anemia due to intrinsic factor deficiency (intrinsic, factor), D51.2 — Transcobalamin II deficiency (transcobalamine II), D53.0 — Protein deficiency anemia (protein, anemia), D55.0 — Anemia due to glucose-6-phosphate dehydrogenase [G6PD] deficiency (glucose-6-phosphate dehydrogenase, anemia), D56.9 — Thalassemia, unspecified (in, thalassemia NEC), D57 — Sickle-cell disorders (gouty, in, sickle-cell disorders), D58.2 — Other hemoglobinopathies (in, hemoglobinopathy NEC), D64.9 — Anemia, unspecified (hemoglobin), D65 — Disseminated intravascular coagulation [defibrination syndrome] (fibrinogen, acquired), D67 — Hereditary factor IX deficiency (B), D68.01 — Von Willebrand disease, type 1 (von Willebrand factor, partial quantitative), D68.03 — Von Willebrand disease, type 3 (von Willebrand factor, total quantitative), D68.1 — Hereditary factor XI deficiency (C), D68.2 — Hereditary deficiency of other clotting factors (SPCA), D68.311 — Acquired hemophilia (acquired), D68.4 — Acquired coagulation factor deficiency (calcipriva), D68.59 — Other primary thrombophilia (protein, S), D68.8 — Other specified coagulation defects (factor, multiple), D68.9 — Coagulation defect, unspecified (clotting), +492 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Fecal Occult Blood Test (FOBT), Iron Panel, Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of D66 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 D66 with these 17 related codes in Claim Check

Hierarchy

Excludes1

  • D68.0 — Von Willebrand disease[Excludes1]: “factor VIII deficiency with vascular defect (D68.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes1 notes

Referenced by Excludes2 notes (10)

Referenced by Code First instructions (22)

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 111 — Hemophilia, Male [CMS-HCC]: “Hemophilia, Male — supersedes HCC 112 (Immune Thrombocytopenia and Specified Coagulation Defects and Hemorrhagic Conditions)”— CMS-HCC V28 · 2026

MS-DRG Grouper

  • MCC — Major Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (MCC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
  • DRG 813 — COAGULATION DISORDERS[MS-DRG]: “COAGULATION DISORDERS (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 (11)

  • Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute), due to or associated with, hemophilia[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute), in (due to), hemophilia NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Arthropathy, hemophilic NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Arthropathy, in (due to), hemophilia NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Deficiency, deficient, anti-hemophilic, factor (A)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Deficiency, deficient, anti-hemophilic, globulin NEC (AHG)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Deficiency, deficient, factor, VIII (congenital) (functional) (hereditary) (with functional defect)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disease, diseased, bleeder's[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 3 more

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
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release 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. "D66 — Hereditary factor VIII deficiency." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/d66-hereditary-factor-viii-deficiency

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Hereditary factor VIII deficiency

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.