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E87.21 ICD-10-CM Code: Acute metabolic acidosis

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 inclusion term · 11 Excludes1 · 1 Excludes2

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 640 — MISCELLANEOUS DISORDERS OF NUTRITION, METABOLISM, FLUIDS AND ELECTROLYTES WITH MCC (MDC 10)
  • MS-DRG 641 — MISCELLANEOUS DISORDERS OF NUTRITION, METABOLISM, FLUIDS AND ELECTROLYTES WITHOUT MCC (MDC 10)
  • MS-DRG 791 — PREMATURITY WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for E87.21 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on E87.21 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Acute lactic acidosis

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from E70-E88

Coder workflow for E87.21

MedCoder structured workflow — derived from this code’s own official record

Before you code E87.21

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with E87.21. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in E87.21’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewE11, E13, E23.2, O21.1, O08.5, G72.3

Consider E87.21. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Acuity
Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).

Official instructions as workflow

  • Excludes1 — check before selecting E87.21(11 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with E87.21: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareE11, E13, E23.2, O21.1, O08.5, G72.3

    See the official tabular notes · Guidelines I.A.12.a

  • Excludes2 — not part of E87.21(1 note)

    Coding workflow: The conditions named in this note are not included in E87.21. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareQ79.6

    See the official tabular notes · Guidelines I.A.12.b

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: Both the condition E87.21 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewE11, E13, E23.2, O21.1, O08.5, G72.3

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Acute metabolic acidosis is a billable ICD-10-CM diagnosis code (E87.21).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (3)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name E87.21 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: P59 — Neonatal jaundice from other and unspecified causes (via E87.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 15 Excludes2 notes across 4 chapters: G11 — Hereditary ataxia (via E87.-), G71 — Primary disorders of muscles (via E87.-), N25.0 — Renal osteodystrophy (via E87.-), N25.81 — Secondary hyperparathyroidism of renal origin (via E87.-), R79.1 — Abnormal coagulation profile (via E87.-), T80 — Complications following infusion, transfusion and therapeutic injection (via E87.-), T80-T88 — Complications of surgical and medical care, not elsewhere classified (T80-T88) (via E87.-), T81 — Complications of procedures, not elsewhere classified (via E87.-), T82 — Complications of cardiac and vascular prosthetic devices, implants and grafts (via E87.-), T83 — Complications of genitourinary prosthetic devices, implants and grafts (via E87.-), T84 — Complications of internal orthopedic prosthetic devices, implants and grafts (via E87.-), T85 — Complications of other internal prosthetic devices, implants and grafts (via E87.-), T86 — Complications of transplanted organs and tissue (via E87.-), T87 — Complications peculiar to reattachment and amputation (via E87.-), T88 — Other complications of surgical and medical care, not elsewhere classified (via E87.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 2 Code First instructions across 2 chapters: G63 — Polyneuropathy in diseases classified elsewhere (via E87.-), H42 — Glaucoma in diseases classified elsewhere (via E87.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 2 Use Additional Code instructions across 2 chapters: E86 — Volume depletion (via E87.-), G90.81 — Serotonin syndrome (via E87.2.-).

These codes instruct coders to additionally report this code when it applies.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 17 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 4 MS-DRGs: DRG 640 (MDC 10), DRG 641 (MDC 10), DRG 791 (MDC 15), DRG 793 (MDC 15).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):END011 — Fluid and electrolyte disorders (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

E86.0 — Dehydration, E86.1 — Hypovolemia, E86.9 — Volume depletion, unspecified, E87.0 — Hyperosmolality and hypernatremia, E87.1 — Hypo-osmolality and hyponatremia, E87.20 — Acidosis, unspecified, E87.22 — Chronic metabolic acidosis, E87.29 — Other acidosis, E87.3 — Alkalosis, E87.4 — Mixed disorder of acid-base balance, E87.5 — Hyperkalemia, E87.6 — Hypokalemia, E87.70 — Fluid overload, unspecified, E87.71 — Transfusion associated circulatory overload, E87.79 — Other fluid overload, E87.8 — Other disorders of electrolyte and fluid balance, not elsewhere classified

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Fluid and electrolyte disorders).

E86.0 — Dehydration, E86.1 — Hypovolemia, E86.9 — Volume depletion, unspecified, E87.0 — Hyperosmolality and hypernatremia, E87.1 — Hypo-osmolality and hyponatremia, E87.2 — Acidosis, E87.20 — Acidosis, unspecified, E87.22 — Chronic metabolic acidosis, E87.29 — Other acidosis, E87.3 — Alkalosis, E87.4 — Mixed disorder of acid-base balance, E87.5 — Hyperkalemia, E87.6 — Hypokalemia, E87.70 — Fluid overload, unspecified, E87.71 — Transfusion associated circulatory overload, E87.79 — Other fluid overload, E87.8 — Other disorders of electrolyte and fluid balance, not elsewhere classified

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Acidosis”; these codes share that main term but sit in a different category of the Tabular List.

E10.10 — Type 1 diabetes mellitus with ketoacidosis without coma (in Type 1 diabetes), E10.11 — Type 1 diabetes mellitus with ketoacidosis with coma (in Type 1 diabetes, with coma), J96.02 — Acute respiratory failure with hypercapnia (respiratory, acute), J96.12 — Chronic respiratory failure with hypercapnia (respiratory, chronic), N25.89 — Other disorders resulting from impaired renal tubular function (renal), P74.0 — Late metabolic acidosis of newborn (metabolic NEC, late, of newborn), P74.421 — Hyperchloremia of newborn (metabolic NEC, hyperchloremic, of newborn), P84 — Other problems with newborn (newborn)

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Blood Glucose Test

Contextual Map

Every relationship of E87.21 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run E87.21 with these 13 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes (15)

Referenced by Code First instructions

Referenced by Use Additional Code instructions

  • E86 — Volume depletion[Use Additional Code](via E87.-): “code(s) for any associated disorders of electrolyte and acid-base balance (E87.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • G90.81 — Serotonin syndrome[Use Additional Code](via E87.2.-): “metabolic acidosis (E87.2-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 10 — Endocrine, Nutritional and Metabolic Diseases and Disorders[MDC crossing]: “Endocrine, Nutritional and Metabolic Diseases and Disorders — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 5,008 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
  • MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

  • Acidosis (lactic), lactic, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Acidosis (lactic), metabolic NEC, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disorder (of), electrolyte NEC (balance), acidosis (lactic) (metabolic), acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (16)

Change history

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "E87.21 — Acute metabolic acidosis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/e87.21-acute-metabolic-acidosis

Change history

  • FY2023 — October 1, 2022
    Added to the code set
    Acute metabolic acidosis
    FY2023 changes

Nearest Codes in This Family

Official ICD-10-CM classifications closest to E87.21 in its code family, with their registry titles.

View all codes in the E87 family