E87.20: Acidosis, unspecified

The ICD-10-CM code for acidosis, including lactic acidosis NOS and metabolic acidosis NOS, when the provider documents neither an acute nor a chronic course and no other type of acidosis.

Billable

FY2027

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At a glance

Code Family

E87.2: Acidosis

DRG Grouping

MS-DRG 640 or 641, Miscellaneous disorders of nutrition, metabolism, fluids and electrolytes, when E87.20 is the principal diagnosis under the FY2027 MS-DRG v44 grouper.

HCC Mapping (v28)

Indeterminate. E87.20 is absent from the bundled FY2022 to FY2023 v28 crosswalk.

Family Specificity

Four billable codes sit in E87.2, including E87.20, split by acuity and by metabolic versus other acidosis.

Billable

Yes. E87.20 is a complete code in the FY2027 billable code list.

Effective Date

Valid in the FY2026 code set and unchanged in the FY2027 update.

Which E87.2 code do I assign?

Subcategory E87.2 splits acidosis by course and type: unspecified, acute metabolic, chronic metabolic and other acidosis. Diabetic ketoacidosis, renal tubular acidosis, mixed acid-base disorders and newborn acidosis leave E87.2 for their own codes.

When documentation says…

Code

Lactic acidosis or metabolic acidosis, no acuity stated

E87.20

Acidosis, unspecified. Lactic acidosis NOS and metabolic acidosis NOS are inclusion terms here. The Index sends Acidosis, Acidosis, lactic and Acidosis, metabolic NEC to E87.20, along with Acidemia and Lacticemia, excessive.

Acute lactic acidosis or acute metabolic acidosis

E87.21

Acute metabolic acidosis. Acute lactic acidosis is an inclusion term. The Index sends the acute subterm under both lactic and metabolic acidosis here. The note must use the word acute.

Chronic metabolic acidosis

E87.22

Chronic metabolic acidosis. Chronic lactic acidosis is an inclusion term. E87.22 carries a Code first, if applicable, note for the underlying etiology. The note must use the word chronic and should name the cause.

Respiratory acidosis, acuity not stated

E87.29

Other acidosis. Respiratory acidosis NOS is an inclusion term. The Index sends Acidosis, specified NEC and Ketoacidosis without a diabetic link here. Acute respiratory acidosis indexes to J96.02 and chronic respiratory acidosis to J96.12.

DKA in type 1 diabetes, or acidosis in type 1 diabetes

E10.10

Type 1 diabetes mellitus with ketoacidosis without coma. The Index sends Acidosis, in Type 1 diabetes here and to E10.11 with coma. The E87.2 Excludes1 note sends diabetic acidosis to the ketoacidosis codes in categories E08-E10, E11 and E13. Type 2 diabetes with ketoacidosis is E11.10.

Mixed metabolic and respiratory acidosis

E87.4

Mixed disorder of acid-base balance. The Index sends Acidosis, metabolic NEC, with respiratory acidosis here. Respiratory acidosis complicated by metabolic acidosis or alkalosis indexes to E87.4 as well.

Renal tubular acidosis

N25.89

Other disorders resulting from impaired renal tubular function. Renal tubular acidosis NOS is an inclusion term. The Index sends Acidosis, renal and Acidosis, kidney, tubular here rather than to E87.2.

Tabular notes

EXCLUDES1

Subcategory E87.2 carries an Excludes1 note for diabetic acidosis, which it sends to categories E08-E10, E11 and E13 with ketoacidosis. E87.20 and a diabetic ketoacidosis code are not reported together for the same condition.

Category E87 carries an Excludes1 note for diabetes insipidus (E23.2), electrolyte imbalance associated with hyperemesis gravidarum (O21.1), electrolyte imbalance following ectopic or molar pregnancy (O08.5), familial periodic paralysis (G72.3) and metabolic acidemia in newborn, unspecified (P19.9).

Chapter 4 carries an Excludes1 note for transitory endocrine and metabolic disorders specific to newborn (P70-P74). The Index sends late metabolic acidosis of newborn to P74.0. E87.20 carries no Excludes1 note of its own.

EXCLUDES2

E87.20 carries no Excludes2 note. Its sibling E87.29 carries an Excludes2 note for acute respiratory acidosis (J96.02) and chronic respiratory acidosis (J96.12).

Block E70-E88 carries an Excludes2 note for Ehlers-Danlos syndromes (the Q79.6 codes). The patient may have both conditions.

CODE ALSO

E87.20 carries a Code also, if applicable, note for respiratory failure with hypercapnia (J96. with 5th character 2). The codes it points to are J96.02, J96.12, J96.22 and J96.92.

A code also note does not set sequencing. The circumstances of the encounter decide which code comes first (Guideline I.A.17). E87.21 and E87.22 carry no matching note.

CODE FIRST

E87.20 carries no code first note. None sits above it at E87.2, E87, block E70-E88 or Chapter 4.

Its sibling E87.22 carries a Code first, if applicable, note for the underlying etiology. When the provider names the cause of chronic metabolic acidosis, that condition is sequenced before E87.22.

USE ADDITIONAL

E87.20 carries no use additional code note. None sits above it at E87.2, E87, block E70-E88 or Chapter 4.

In the other direction, G90.81 Serotonin syndrome carries a Use additional code, if applicable, note that names metabolic acidosis (the E87.2 codes). G90.81 is listed first in that case.

FY2027: EFFECTIVE 1 OCTOBER 2026

The FY2027 codes addenda make no addition, deletion or revision in category E87. E87.20 is in the FY2027 billable code list and its notes are unchanged.

The FY2027 tabular addenda revised the E87.22 Code first note from "underlying etiology, if applicable" to ", if applicable, underlying etiology". The revision reorders the same words.

Operational & financial impact

Why specificity matters beyond the chart: risk adjustment, DRG assignment and denial exposure all follow from which code is selected.

CMS-HCC v28 (PY2024+)

No code in category E87 appears in the CMS-HCC v28 diagnosis crosswalk bundled with the model software. E87.21, E87.22 and E87.29 are absent along with E87.20.

In the same crosswalk, E08.10, E10.10, E11.10 and E13.10 map to HCC 36: Diabetes with Severe Acute Complications.

J96.02, J96.12, J96.22 and J96.92 map to HCC 213: Cardio-Respiratory Failure and Shock.

MS-DRG v44 (FY2027)

MS-DRG 640: Miscellaneous disorders of nutrition, metabolism, fluids and electrolytes with MCC.

MS-DRG 641: Miscellaneous disorders of nutrition, metabolism, fluids and electrolytes without MCC.

E87.20 as principal diagnosis groups to one of these two medical DRGs in MDC 10, per the CMS MS-DRG v44.0 Definitions Manual, Appendix B.

WHERE SPECIFICITY IS LOST

Reporting E87.20 when the provider documents acute or chronic acidosis drops the course that E87.21 and E87.22 carry.

Reporting E87.20 for diabetic ketoacidosis conflicts with the E87.2 Excludes1 note. The ketoacidosis codes map to HCC 36.

Reporting E87.20 alone when the provider documents hypercapnic respiratory failure omits the J96 code that the E87.20 code also note points to.

Reporting E87.20 for acute respiratory acidosis misses the Index route to J96.02, which maps to HCC 213.

SEVERITY DESIGNATION (MS-DRG V44, FY2027)

E87.20 is on Table 6J. It is a CC as a secondary diagnosis unless the principal diagnosis excludes it under the CC Exclusions List in Appendix C of the MS-DRG v44 Definitions Manual.

E87.21, acute metabolic acidosis, E87.22, chronic metabolic acidosis, and E87.29, other acidosis, are CCs as well.

Per Table 6I (Complete MCC List) and Table 6J (Complete CC List) of the FY2027 IPPS final rule (CMS-1849-F), MS-DRG v44.

Documentation checklist to support E87.20

Chart elements that support code selection and reduce specificity-driven denials.

The type of acidosis in the provider's own words, such as lactic, metabolic, respiratory, renal tubular or diabetic ketoacidosis.

The course of the acidosis. The words acute or chronic move the code from E87.20 to E87.21 or E87.22.

The underlying cause the provider links to the acidosis, such as sepsis, shock, kidney disease or a drug. E87.22 carries a code first note for the etiology.

Whether the patient has diabetes, the diabetes type and whether the provider documents ketoacidosis, with or without coma.

Any respiratory failure with hypercapnia, which the E87.20 code also note points to the J96 codes with 5th character 2.

Whether the provider describes a mixed metabolic and respiratory disorder, which indexes to E87.4.

The drug and the provider's link to it when the acidosis is an adverse effect of a correctly prescribed medication, which adds a T36-T50 code (Guideline I.C.19.e.5.(a)).

The provider's statement of the diagnosis rather than a lactate or blood gas value alone. Abnormal findings are not coded unless the provider indicates their clinical significance (Section III.B).

Whether the patient is a newborn. Newborn acidosis indexes to P84. The E87 Excludes1 note bars reporting P19.9 with E87.20 for the same condition.

FAQ

Is E87.20 a billable code?

Yes. E87.20 is a complete code with no further characters. It appears in the FY2027 billable code list. Its parent E87.2 is a subcategory and cannot be reported.

What is the ICD-10 code for lactic acidosis or metabolic acidosis?

E87.20 when the provider states no course. Lactic acidosis NOS and metabolic acidosis NOS are both inclusion terms at E87.20. The Index sends acute lactic or metabolic acidosis to E87.21 and chronic lactic or metabolic acidosis to E87.22.

When is a diabetic ketoacidosis code used instead of E87.20?

When the provider links the acidosis to diabetes. Subcategory E87.2 carries an Excludes1 note for diabetic acidosis, which it sends to the ketoacidosis codes by diabetes type, such as E10.10 and E11.10. The two are not reported together for the same condition. The Index sends Acidosis, in Type 1 diabetes to E10.10.

Does E87.20 map to an HCC under CMS-HCC v28?

Its mapping is indeterminate. E87.20 is absent from the bundled FY2022 to FY2023 v28 crosswalk. The diabetic ketoacidosis codes E08.10, E10.10, E11.10 and E13.10 map to HCC 36.

How is acute on chronic metabolic acidosis coded?

The Index lists acute and chronic as separate subterms at the same level under lactic acidosis and under metabolic acidosis. Guideline I.B.8 then calls for both codes with the acute code first. Report E87.21 followed by E87.22.

When is a J96 code reported with E87.20?

E87.20 carries a Code also, if applicable, note for respiratory failure with hypercapnia. When the provider documents it, add J96.02, J96.12, J96.22 or J96.92 by course. The note sets no sequencing (Guideline I.A.17).

How is E87.20 sequenced in inpatient and outpatient settings?

As principal diagnosis, E87.20 groups to MS-DRG 640 or 641. An uncertain diagnosis documented at inpatient discharge is coded as if it existed (Section II.H). In the outpatient setting, a probable or suspected diagnosis is not coded (Section IV.H). Code the highest degree of certainty instead.

What changed for E87.20 in FY2027?

Nothing in the code or its notes. The FY2027 codes addenda make no change in category E87. The FY2027 tabular addenda reordered the wording of the E87.22 Code first note for the underlying etiology.

Related codes

Codes in the same family as E87.20. Only codes with a published page render as links.

Sibling codes in the E87.2 family

E87.21: Acute metabolic acidosis, when the provider documents acute lactic or metabolic acidosis.
E87.22: Chronic metabolic acidosis, when the provider documents chronic lactic or metabolic acidosis.
E87.29: Other acidosis, when respiratory acidosis NOS or another specified acidosis is documented.

Additional codes to consider

Codes outside the E87.2 family considered alongside E87.20.

Companion: code alongside when documented

J96.02: Acute respiratory failure with hypercapnia, under the E87.20 code also note when acute hypercapnic respiratory failure is documented.
J96.12: Chronic respiratory failure with hypercapnia, under the E87.20 code also note when chronic hypercapnic respiratory failure is documented.
J96.22: Acute and chronic respiratory failure with hypercapnia, under the E87.20 code also note when acute on chronic hypercapnic respiratory failure is documented.
J96.92: Respiratory failure, unspecified with hypercapnia, under the E87.20 code also note when the course of hypercapnic respiratory failure is not stated.
T38.3X5A: Adverse effect of insulin and oral hypoglycemic [antidiabetic] drugs, initial encounter, when the provider attributes the acidosis to metformin, which the Table of Drugs sends to T38.3X5.
G90.81: Serotonin syndrome, listed before the acidosis code when its use additional code note for metabolic acidosis applies.

Consider instead

E87.21: Acute metabolic acidosis, when the provider documents acute lactic or metabolic acidosis.
E87.22: Chronic metabolic acidosis, when the provider documents chronic lactic or metabolic acidosis.
E10.10: Type 1 diabetes mellitus with ketoacidosis without coma, when DKA or acidosis in type 1 diabetes is documented.
E11.10: Type 2 diabetes mellitus with ketoacidosis without coma, when ketoacidosis in type 2 diabetes is documented.
E87.4: Mixed disorder of acid-base balance, when metabolic acidosis with respiratory acidosis is documented.
N25.89: Other disorders resulting from impaired renal tubular function, when renal tubular acidosis is documented.
J96.02: Acute respiratory failure with hypercapnia, when acute respiratory acidosis is documented.
P84: Other problems with newborn, when acidosis in a newborn is documented.
P74.0: Late metabolic acidosis of newborn, when late metabolic acidosis of newborn is documented.

Sources

All claims on this page derive from government and professional-standards sources.

National Center for Health Statistics. (2026). International classification of diseases, tenth revision, clinical modification (ICD-10-CM) FY2027 files. https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
Centers for Medicare & Medicaid Services and National Center for Health Statistics. (2026). ICD-10-CM official guidelines for coding and reporting FY2027. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf
Centers for Medicare & Medicaid Services. (2025). 2026 model software/ICD-10 mappings. https://www.cms.gov/medicare/payment/medicare-advantage-rates-statistics/risk-adjustment/2026-model-software-icd-10-mappings
Centers for Medicare & Medicaid Services. (2026). MS-DRG classifications and software, version 44. https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software