E87.5: Hyperkalemia

The ICD-10-CM code for hyperkalemia, an elevated serum potassium documented by the provider as a clinical finding that was evaluated or managed at the encounter.

Billable

FY2027

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At a glance

Code Family

E87: Other disorders of fluid, electrolyte and acid-base balance.

Condition

Hyperkalemia

Billable

Yes

HCC Mapping (v28)

None. E87.5 does not map to an HCC category under CMS-HCC v28.

DRG Grouping

MS-DRG 640 or 641 under the FY2027 MS-DRG v44 grouper, determined by the presence of a major complication or comorbidity.

Family Specificity

Category E87 splits by the specific fluid, electrolyte or acid-base disturbance documented. E87.5 is the code for an elevated serum potassium.

Which E87 code do I assign?

Category E87 splits on which fluid, electrolyte or acid-base disturbance the provider documents, not on how severe it is. Match the code to the analyte named in the note and to the direction of the abnormality.

When documentation says…

Code

Hyperkalemia, potassium 5.8, treated with IV calcium gluconate

E87.5

An elevated serum potassium documented by the provider as a clinical finding. The note must state hyperkalemia or elevated potassium. It must also show that the finding was evaluated or managed at the encounter.

Hypokalemia, potassium 2.9, repleted

E87.6

A low serum potassium. E87.5 and E87.6 describe opposite disturbances and cannot both apply to the same documented finding.

Hyponatremia

E87.1

Hypo-osmolality and hyponatremia. This code covers a low serum sodium rather than an elevated potassium.

Metabolic acidosis with elevated potassium

E87.20

Acidosis, unspecified. The Alphabetic Index sends metabolic acidosis NEC to E87.20, acute metabolic acidosis to E87.21 and chronic metabolic acidosis to E87.22. Assign E87.5 additionally when the provider separately documents hyperkalemia.

Hyperkalemia secondary to stage 5 chronic kidney disease

N18.5

Chronic kidney disease, stage 5. No tabular note links N18.5 and E87.5. The condition chiefly responsible for the encounter is sequenced first. E87.5 is assigned as well to capture the electrolyte abnormality.

Hyperkalemia due to ACE inhibitor

T46.4X5A

Adverse effect of angiotensin-converting-enzyme inhibitors, initial encounter. E87.5 is sequenced first as the nature of the adverse effect. The T-code identifying the drug follows it.

Periodic paralysis

G72.3

Periodic paralysis, which carries familial and hyperkalemic periodic paralysis as inclusion terms. The Excludes1 note at category E87 for familial periodic paralysis (G72.3) bars E87.5 for the same condition.

Tabular notes

EXCLUDES1

Category E87 carries an Excludes1 note. An Excludes1 note means the excluded conditions are not reported with E87.5 for the same condition. Guideline I.A.12.a allows both codes when the conditions are unrelated. The excluded conditions are 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).

FY2027: EFFECTIVE 1 OCTOBER 2026

The FY2027 codes addenda add and delete no codes in category E87. The only FY2027 tabular change in the category rewords the Code first note at E87.22, chronic metabolic acidosis. E87.5 and the E87 Excludes1 note are unchanged in the FY2027 update. No FY2026 changes were identified for E87.5 or for parent category E87.

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+)

E87.5 does not map to an HCC category under CMS-HCC v28. The code carries no risk adjustment weight on its own.

The underlying cause is where the risk adjustment value sits. Chronic kidney disease at stage 3 or higher (N18.30 to N18.6) and primary adrenocortical insufficiency (E27.1) map to v28 HCCs. They are coded when the provider establishes them.

Hyperkalemia recorded in the setting of chronic kidney disease should prompt assignment of the chronic kidney disease stage from category N18.

V24 TO V28 TRANSITION

E87.5 carried no HCC mapping under CMS-HCC v24. That absence is unchanged under CMS-HCC v28.

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.

E87.5 as a principal inpatient diagnosis groups under MDC 10, endocrine, nutritional and metabolic diseases and disorders, in the FY2027 MS-DRG v44 grouper.

E87.5 is not itself classified as a CC or an MCC. The tier between MS-DRG 640 and MS-DRG 641 depends on companion diagnoses.

Medicare and commercial payers

Medicare: E87.5 supports medical necessity for laboratory monitoring such as a basic or comprehensive metabolic panel, for cardiac monitoring such as an EKG for peaked T waves, and for electrolyte management services.

WHERE SPECIFICITY IS LOST

Assigning E87.5 without the chronic kidney disease stage code leaves the risk adjustment value of the N18 category uncaptured.

Reporting E87.5 from a laboratory value alone, with no provider documentation that the finding was evaluated or managed, does not meet the official guideline for coding abnormal findings.

Reversing adverse effect sequencing, by listing the drug T-code ahead of E87.5, misstates the nature of the adverse effect as secondary.

Documentation checklist to support E87.5

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

Explicit provider documentation of hyperkalemia or elevated potassium as a clinical finding or diagnosis. The provider's statement governs, not the laboratory value alone.

Laboratory correlation showing a serum potassium above the laboratory's upper reference limit, stated as 5.0 to 5.5 mEq/L depending on the laboratory.

Evidence that the finding was clinically evaluated or managed at the encounter. An abnormal laboratory value not addressed by the provider is not coded.

The direction of the potassium abnormality stated plainly, which separates E87.5 from E87.6 for hypokalemia.

The established underlying cause where one exists, such as a staged chronic kidney disease code from category N18 or primary adrenocortical insufficiency (E27.1), sequenced by the reason for the encounter.

The drug and drug class where the hyperkalemia is documented as drug-induced, to support the adverse effect T-code.

The management provided on the inpatient side, such as intravenous calcium gluconate, sodium bicarbonate, a potassium binder or dialysis.

FAQ

Is E87.5 a billable code?

Yes. E87.5 is a valid, billable ICD-10-CM code for HIPAA-covered transactions. It has no child codes. No further character is required.

Can E87.5 and E87.6 be coded together?

E87.5 and E87.6 are not coded together for the same finding. No Excludes1 note links E87.5 and E87.6. Hyperkalemia and hypokalemia are opposite electrolyte disturbances. Assign the code that matches the finding documented at that encounter. Where potassium fluctuates between visits, assign the code corresponding to the finding at each specific encounter.

Does E87.5 map to an HCC?

No. E87.5 carries no HCC mapping under CMS-HCC v28. It carried no mapping under CMS-HCC v24 either. The risk adjustment value in these charts comes from the underlying condition, such as chronic kidney disease at stage 3 or higher (N18.30 to N18.6).

Is E87.5 appropriate when potassium is only mildly elevated, such as 5.1?

Code selection follows the provider's clinical documentation, not a fixed laboratory threshold. Where the provider documents and evaluates hyperkalemia at the encounter, E87.5 is appropriate regardless of the degree of elevation. ICD-10-CM does not sub-classify hyperkalemia by severity.

How is drug-induced hyperkalemia sequenced?

Sequence E87.5 first as the nature of the adverse effect. The adverse effect code from T36–T50, with a fifth or sixth character 5, follows it (Guideline I.C.19.e.5.a). For an angiotensin-converting-enzyme inhibitor at an initial encounter the adverse effect code is T46.4X5A. For an electrolytic agent such as a potassium supplement it is T50.3X5A.

Which code comes first when hyperkalemia is caused by chronic kidney disease?

The chronic kidney disease is sequenced first where it is the condition chiefly responsible for the encounter. E87.5 is then assigned as an additional diagnosis to capture the electrolyte abnormality.

Does E87.5 carry a Use Additional or Code First instruction?

No. E87.5 carries no mandatory tabular Use Additional, Code First or Code Also instruction. Sequencing of the underlying cause is directed by the official coding guidelines rather than by a tabular note.

How does coding differ between the outpatient and inpatient settings?

Outpatient: E87.5 is reported for laboratory-confirmed hyperkalemia that the provider evaluates or manages at the encounter. Inpatient: hyperkalemia requiring management such as intravenous calcium gluconate, sodium bicarbonate, a potassium binder or dialysis is captured as a principal or secondary diagnosis. Where the admission is for another condition, E87.5 is coded as a secondary diagnosis.

Related codes

Codes in the same family as E87.5. Only codes with a published page render as links.

Sibling codes in the E87 family

E87.0: Hyperosmolality and hypernatremia.
E87.1: Hypo-osmolality and hyponatremia.
E87.2-: Acidosis.
E87.3: Alkalosis.
E87.4: Mixed disorder of acid-base balance.
E87.6: Hypokalemia.
E87.7-: Fluid overload.
E87.8: Other disorders of electrolyte and fluid balance, not elsewhere classified.

Additional codes to consider

Codes outside the E87 family considered alongside E87.5.

Companion: code alongside when documented

T46.4X5A: Adverse effect of angiotensin-converting-enzyme inhibitors, initial encounter, sequenced after E87.5 under Guideline I.C.19.e.5.a.
T46.5X5A: Adverse effect of other antihypertensive drugs, initial encounter, sequenced after E87.5 under Guideline I.C.19.e.5.a.
T50.3X5A: Adverse effect of electrolytic, caloric and water-balance agents, initial encounter, sequenced after E87.5 under Guideline I.C.19.e.5.a.

Consider instead

E87.6: Hypokalemia, where the documented abnormality is a low serum potassium.
E87.2-: Acidosis, where the documented disturbance is acid-base rather than a potassium level.
E87.8: Other disorders of electrolyte and fluid balance, not elsewhere classified.
G72.3: Periodic paralysis, excluded from category E87 by an Excludes1 note.
E23.2: Diabetes insipidus, excluded from category E87 by an Excludes1 note.

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