D84.1 — Defects in the complement system
D84.1 is a billable, specific ICD-10-CM code for defects in the complement system. It is valid for submission on a claim.
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- C1 esterase inhibitor [C1-INH] deficiency
Other codes that can never be billed with D84.1
These codes carry an Excludes1 note pointing at D84.1. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading D84.1 alone.
Risk adjustment
D84.1 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:
- HCC 115 Specified Immunodeficiencies and White Blood Cell Disorders0.565 RAF
Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.
Medicare coverage
D84.1 is named in 20 Medicare coverage policies — 20 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A55717Billing and Coding: Lab: Flow Cytometry
- A56464Billing and Coding: Flow Cytometry
- A56638Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs)
- A56642Billing and Coding: Gastrointestinal Pathogen (GIP) Panels Utilizing Multiplex Nucleic Acid Amplification Techniques (NAATs)
How D84.1 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to D84.1.
- Angioedema›hereditary
- Angioneurotic edema›hereditary
- Bannister's disease›hereditary
- Defect, defective›complement system
- Deficiency, deficient›C1 esterase inhibitor(C1-INH)
- Quincke's disease or edema›hereditary
- Edema, edematous›angioneurotic›hereditary
- Edema, edematous›circumscribed, acute›hereditary
- Edema, edematous›essential, acute›hereditary
- Edema, edematous›periodic›hereditary
- Edema, edematous›Quincke's›hereditary
- Giant›urticaria›hereditary
Related codes at this level
Codes that share D84. If D84.1 is not quite right, the correct code is usually one of these.
Questions about D84.1
- Is D84.1 a billable ICD-10-CM code?
- Yes. D84.1 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does D84.1 sit in the tabular list?
- Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89), in the block Certain disorders involving the immune mechanism (D80-D89).