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ICD-10-CM D84.821: Immunodeficiency due to drugs

D84.821 is the billable ICD-10-CM code for immunodeficiency due to drugs, in category D84 (Other immunodeficiencies) of the Certain disorders involving the immune mechanism section. As a principal diagnosis it groups to MS-DRG 814 Reticuloendothelial and Immunity Disorders with MCC, MS-DRG 815 Reticuloendothelial and Immunity Disorders with CC, MS-DRG 816 Reticuloendothelial and Immunity Disorders without CC/MCC (MDC 16 MDC 16: Diseases and Disorders of Blood, Blood Forming Organs and Immunologic Disorders). As a secondary diagnosis it is a CC, excluded with 44 principal diagnoses. 10 LCD billing and coding articles list it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
D84.821
billable FY2027 ICD-10-CM code
Category
D84 Other immunodeficiencies
Chapter
3: Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89)
CC/MCC (MS-DRG v44)
CC
CMS-HCC V28
Not mapped
POA reporting
Required

Tabular list notes for D84.821

The tabular list has no notes on D84.821 itself; the notes below apply from its parent headings.

MS-DRG grouping when D84.821 is the principal diagnosis

MS-DRG v44 groups for D84.821 as principal diagnosis
MDCMS-DRGs
16 MDC 16: Diseases and Disorders of Blood, Blood Forming Organs and Immunologic Disorders814815816

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for D84.821 shows the full grouping logic.

CC/MCC status and inpatient edits

As a secondary diagnosis, D84.821 is a CC under MS-DRG v44, unless the principal diagnosis is one of the 44 codes in its exclusion list. Check D84.821 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.

CMS-HCC V28 risk adjustment

D84.821 does not map to a payment HCC in the PY2027 CMS-HCC V28 model, so on its own it does not change a Medicare Advantage risk score.

LCD billing and coding articles that list D84.821

10 current Medicare billing and coding articles list D84.821 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM D84.821 mean?

D84.821 means immunodeficiency due to drugs. It is one of 7 billable codes under D84, other immunodeficiencies.

Which MS-DRG does D84.821 group to?

As the principal diagnosis, D84.821 groups to MS-DRG 814 Reticuloendothelial and Immunity Disorders with MCC, MS-DRG 815 Reticuloendothelial and Immunity Disorders with CC, MS-DRG 816 Reticuloendothelial and Immunity Disorders without CC/MCC (MDC 16 MDC 16: Diseases and Disorders of Blood, Blood Forming Organs and Immunologic Disorders) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Is D84.821 a CC or MCC?

D84.821 is a CC under MS-DRG v44; 44 principal diagnoses exclude it.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.