ICD-10 code for immune mechanism immunity disorder

The ICD-10-CM code for immune mechanism immunity disorder is D89.9 (Disorder involving the immune mechanism, unspecified). The official index lists 1 more specific code, so check the documentation for details such as type, cause, site or severity before settling on D89.9.

Within D89, choose D89.9 (Disorder involving the immune mechanism, unspecified) only when documentation doesn't support a more specific option: Polyclonal hypergammaglobulinemia (D89.0), Cryoglobulinemia (D89.1), hypergammaglobulinemia, unspecified (D89.2), immune reconstitution syndrome (D89.3), mast cell activation syndrome and related disorders (D89.4) and other specified disorders involving the immune mechanism, not elsewhere classified (D89.8).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 814 (Reticuloendothelial and Immunity Disorders with MCC, relative weight 2.0729), DRG 815 (Reticuloendothelial and Immunity Disorders with CC, relative weight 1.0444) and DRG 816 (Reticuloendothelial and Immunity Disorders without CC/MCC, relative weight 0.7381), in MDC 16 (Diseases and Disorders of the Blood and Blood Forming Organs and Immunological Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.