ICD-10 D84.1
Billable / Specific HCC v28: 23Defects in the complement system
About ICD-10-CM D84.1
ICD-10-CM code D84.1 represents Defects in the complement system. This is a billable/specific code in the Blood and Blood-forming Organs chapter (block D84). The 2026 edition of ICD-10-CM D84.1 became effective on October 1, 2025.
Coding Tips for D84.1
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
D84.1 is a CMS-HCC v28 risk-adjustment code (category 23). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under D84.1. Per CMS ICD-10-CM Tabular 2026.
- C1 esterase inhibitor [C1-INH] deficiency
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for D84.1
Local Coverage Determinations (LCDs) from CMS MACs that list D84.1 as a covered diagnosis.
Showing top 10 of 677 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing D84.1.
5 Medicare
2 Aetna
CPT Codes Commonly Billed with D84.1
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 87507 CMS LCD: Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs) CMS LCD
- 87505 CMS LCD: Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs) CMS LCD
- 87506 CMS LCD: Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs) CMS LCD
- 87812 CMS LCD: Billing and Coding: Respiratory Pathogen Panel Testing CMS LCD
- 87428 CMS LCD: Billing and Coding: Respiratory Pathogen Panel Testing CMS LCD
- 87913 CMS LCD: Billing and Coding: Respiratory Pathogen Panel Testing CMS LCD
Convert D84.1 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| D84.1 | 2776 | 10000 |
| D84.1 | 2798 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To D84.1
Other codes in section D80-D89 (Certain disorders involving the immune mechanism).
ICD-10 D84.1, Billing FAQ
Is ICD-10 code D84.1 billable? +
Yes, D84.1 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to D84.1? +
ICD-10 D84.1 includes: C1 esterase inhibitor [C1-INH] deficiency.
Does D84.1 affect Medicare Advantage HCC risk adjustment? +
Yes. D84.1 maps to CMS-HCC v28 category 23. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What CPT codes are commonly billed with D84.1? +
Procedures frequently paired with D84.1 include: 87507, 87505, 87506, 87812, 87428.
What ICD-9 codes does D84.1 map to? +
Per CMS GEMs, D84.1 maps to ICD-9 codes: 2776, 2798. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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