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ICD-10 Guide
ICD-10 CodesD81.9

D81.9

Billable

Combined immunodeficiency, unspecified

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/05/2025

Code Description

ICD-10 D81.9 is a billable code used to indicate a diagnosis of combined immunodeficiency, unspecified.

Key Diagnostic Point:

Combined immunodeficiency (CID) refers to a group of disorders characterized by the dysfunction of both humoral and cell-mediated immunity. This condition results in an increased susceptibility to infections, autoimmune diseases, and malignancies. The unspecified designation indicates that the specific type of combined immunodeficiency has not been determined. Patients may present with recurrent infections, failure to thrive, and other systemic symptoms. The underlying pathophysiology often involves genetic mutations affecting lymphocyte development and function, leading to inadequate immune responses. Diagnosis typically involves immunological testing, including lymphocyte counts and functional assays, to assess the integrity of both T and B cell functions. Management may include immunoglobulin replacement therapy, prophylactic antibiotics, and in some cases, hematopoietic stem cell transplantation. Due to the complexity of the immune system, the clinical presentation can vary widely, necessitating a thorough evaluation to guide treatment and monitor for complications.

Code Complexity Analysis

Complexity Rating: High

High Complexity

Complexity Factors

  • Variety of underlying genetic causes
  • Need for comprehensive immunological testing
  • Potential for overlapping symptoms with other disorders
  • Variability in clinical presentation

Audit Risk Factors

  • Inadequate documentation of immunological testing
  • Failure to specify the type of immunodeficiency
  • Lack of clarity in clinical notes regarding symptoms
  • Inconsistent coding across encounters

Specialty Focus

Medical Specialties

Immunology

Documentation Requirements

Detailed immunological assessment results, including lymphocyte counts and functional assays.

Common Clinical Scenarios

Patients presenting with recurrent infections, failure to thrive, or autoimmune manifestations.

Billing Considerations

Ensure that all immunological evaluations are documented to support the diagnosis.

Pediatrics

Documentation Requirements

Growth charts, vaccination history, and detailed accounts of recurrent infections.

Common Clinical Scenarios

Infants or children with failure to thrive and frequent infections.

Billing Considerations

Documenting the timeline of infections and any interventions taken is crucial.

Coding Guidelines

Inclusion Criteria

Use D81.9 When
  • Follow the official ICD
  • CM coding guidelines, ensuring that the diagnosis is supported by clinical documentation
  • Include any relevant laboratory results and treatment plans

Exclusion Criteria

Do NOT use D81.9 When
  • Exclude conditions that are specifically defined in the guidelines

Related ICD-10 Codes

Related CPT Codes

36415CPT Code

Collection of venous blood by venipuncture

Clinical Scenario

Used for obtaining blood samples for immunological testing.

Documentation Requirements

Document the reason for blood draw and any relevant patient history.

Specialty Considerations

Ensure that the specialty performing the test is noted.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of immunodeficiencies, improving the ability to capture the nuances of these complex conditions. D81.9 serves as a catch-all for unspecified cases, highlighting the need for thorough documentation.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of immunodeficiencies, improving the ability to capture the nuances of these complex conditions. D81.9 serves as a catch-all for unspecified cases, highlighting the need for thorough documentation.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of immunodeficiencies, improving the ability to capture the nuances of these complex conditions. D81.9 serves as a catch-all for unspecified cases, highlighting the need for thorough documentation.

Resources

Clinical References

  • •
    American Academy of Allergy, Asthma & Immunology

Coding & Billing References

  • •
    American Academy of Allergy, Asthma & Immunology

Frequently Asked Questions

What should I document to support the use of D81.9?

Document all clinical findings, laboratory results, and any treatments provided. Ensure that the rationale for the diagnosis is clear and supported by evidence.