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D81.6

D81.6Major histocompatibility complex class I deficiency

Billable / specific codeICD-10-CM

D81.6 is a billable, specific ICD-10-CM code for major histocompatibility complex class i deficiency. It is valid for submission on a claim.

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

  • Bare lymphocyte syndrome

Risk adjustment

D81.6 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:

  • HCC 114 Common Variable and Combined Immunodeficiencies2.262 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

D81.6 is named in 33 Medicare coverage policies 33 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A52507External Infusion Pumps - Policy Article
  • A52509Intravenous Immune Globulin - Policy Article
  • A54660Billing and Coding: Coverage of Intravenous Immune Globulin for Treatment of Primary Immune Deficiency Diseases in the Home – Medicare Benefit Policy Manual, Chapter 15, 50.6
  • A55717Billing and Coding: Lab: Flow Cytometry

How D81.6 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 D81.6.

  • Syndromebare lymphocyte
  • Deficiency, deficientmajor histocompatibility complexclass I

Related codes at this level

Codes that share D81. If D81.6 is not quite right, the correct code is usually one of these.

Questions about D81.6

Is D81.6 a billable ICD-10-CM code?
Yes. D81.6 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does D81.6 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).
ICD-10-CMFY2026-Apr· effective April 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release — see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.