ICD-10-CM 2027
ICD-10 code for pneumonia rheumatic
From the official ICD-10-CM alphabetic index entry “Rheumatic (acute) (subacute) › pneumonia”. Page updated September 29, 2026.
About coding pneumonia rheumatic
The ICD-10-CM code for pneumonia rheumatic is I00 (Rheumatic fever without heart involvement).
Don't report I00 together with the conditions in its Excludes1 note: rheumatic fever with heart involvement (I01.0-I01.9).
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 545 (Connective Tissue Disorders with MCC, relative weight 2.3892), DRG 546 (Connective Tissue Disorders with CC, relative weight 1.1745) and DRG 547 (Connective Tissue Disorders without CC/MCC, relative weight 0.7526), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Don't confuse with (Excludes1 for I00)
Common questions about pneumonia rheumatic ICD-10 codes
What is the ICD-10 code for pneumonia rheumatic?
- I00 — Rheumatic fever without heart involvement.
Is I00 billable?
- Yes. I00 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I00 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I00 as a principal diagnosis.
Is I00 a CC or MCC?
- No. I00 is neither a CC nor an MCC under MS-DRG v44.0.