ICDcodes.org
FY2027

E13 vs N16

E13 and N16 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.

The official note, declared on N16
renal tubular degeneration in diabetes (E08-E13 with .29)
E13

Other specified diabetes mellitus

Not billable
Chapter 4
Endocrine, nutritional and metabolic diseases
Section
E08-E13
Use when the record says
  • diabetes mellitus due to genetic defects of beta-cell function
  • diabetes mellitus due to genetic defects in insulin action
  • postpancreatectomy diabetes mellitus
  • postprocedural diabetes mellitus
  • secondary diabetes mellitus NEC
N16

Renal tubulo-interstitial disorders in diseases classified elsewhere

Billable
Chapter 14
Diseases of the genitourinary system
Section
N10-N16
Use when the record says
  • Pyelonephritis
  • Tubulo-interstitial nephritis
Indexed under
  • Disorder › tubulo-interstitial › brucellosis (of)
  • Disorder › tubulo-interstitial › glycogen storage disease (of)
  • Disorder › tubulo-interstitial › leukemia NEC (of)
  • Disorder › tubulo-interstitial › lymphoma NEC (of)
  • Disorder › tubulo-interstitial › mixed cryoglobulinemia (of)

These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.

Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027