E87.6ICD-10-CM

Hypokalemia

BillableNo Excludes1 at the code lineFive exclusions inherited from above

How the code is built

Chapter

Endocrine, nutritional and metabolic diseases

What ICD-10 code E87.6 means

E87.6 is the ICD-10-CM code for hypokalemia. It applies when a provider documents a serum potassium below the reference range as a diagnosis, whatever the cause and whatever the degree.

Potassium deficiency is the inclusion term. The Alphabetic Index also routes hypopotassemia, potassium depletion, and kalium deficiency to this code, so a coder encountering older or less common phrasing lands in the right place. What the code does not carry is severity, acuity, or cause.

Attribute	Detail
Code	E87.6
Descriptor	Hypokalemia
Chapter	Endocrine, nutritional and metabolic diseases
Block	Metabolic disorders
Category	E87, other disorders of fluid, electrolyte and acid-base balance
Billable	Yes
Inclusion term	Potassium deficiency
Excludes1	Five notes, all inherited from category E87

The descriptor has not changed in any fiscal year since 2015. The structural point that matters most is easy to miss: E87.6 has no Excludes1 note on its own line. Every prohibition affecting it sits at the category, block, or chapter level. A coder who checks only the code entry will conclude there are no exclusions at all, and there are five.

2Code structure

What the code absorbs, and what displaces it

E87.6 has no subdivisions. Two facts decide whether it is correct, and the second one is where the exclusions live.

What the single code absorbs

Documented as	Code
Hypokalemia	E87.6
Hypopotassemia or potassium deficiency	E87.6
Mild, moderate, or severe	E87.6, with no severity character
Acute or chronic	E87.6, with no acuity character
With ECG changes or muscle weakness	E87.6, with the manifestations coded separately if documented

What displaces it, all of it inherited

Documented condition	Result
Familial periodic paralysis	G72.3 replaces it, per the category Excludes1
Diabetes insipidus	E23.2 replaces it, per the category Excludes1
Hyperemesis gravidarum, or ectopic or molar pregnancy	The obstetric code replaces it, per the category Excludes1
Newborn	The perinatal chapter code replaces it, per the chapter Excludes1
Congenital adrenal hyperplasia	E25.0 replaces it, per the block Excludes1
Bartter's syndrome, Conn's syndrome, or another named cause	Both are reported, since no exclusion applies
Diuretics, insulin, laxatives, or another drug	E87.6 with the adverse effect code
Hypomagnesemia	Both are reported, since they are separate conditions

The familial periodic paralysis exclusion is the one that catches coders. Hypokalemic periodic paralysis is a channelopathy in which potassium falls episodically and produces weakness or paralysis. It looks like a hypokalemia case on the laboratory report, but the classification treats it as a neuromuscular disorder. When the provider documents familial or hypokalemic periodic paralysis, the encounter belongs to G72.3, and E87.6 is prohibited alongside it.

3Clinical picture

Clinical findings documented under E87.6

A record supporting this code pairs a low potassium result with a provider statement making it a diagnosis.

Laboratory

Serum potassium below the reference range, with magnesium where measured

Neuromuscular

Muscle weakness, cramps, fatigue, reduced deep tendon reflexes

Cardiac

Palpitations, arrhythmia, and ECG changes including T wave flattening and prominent U waves

Gastrointestinal

Constipation, reduced intestinal motility, ileus in severe cases

Renal

Polyuria and increased thirst in chronic depletion

Source of loss

Vomiting, diarrhea, diuretic use, or renal wasting, documented as the mechanism.

The finding that most often changes the coding is magnesium. Hypokalemia that resists replacement is frequently accompanied by hypomagnesemia, and hypomagnesemia has its own code. A record documenting both supports both, and the second one is dropped constantly.

4Documentation

What the chart must show

A provider-stated diagnosis of hypokalemia, since the value alone is a laboratory finding.
The serum potassium result, and the magnesium result when obtained
The route of loss, whether gastrointestinal, renal, or a transcellular shift
Medications contributing to it, including diuretics, insulin, beta-agonists, and laxatives
Any named underlying condition, such as Bartter's syndrome or hyperaldosteronism
Symptoms and ECG findings, documented individually
Treatment given, whether oral or intravenous replacement or a medication change
Monitoring, including repeat testing and cardiac observation

Inpatient reporting turns on a rule outside the tabular list. A secondary diagnosis is reportable when it required clinical evaluation, therapeutic treatment, diagnostic studies, an extended stay, or increased nursing care and monitoring, and the Official Guidelines direct that abnormal findings are not coded unless the provider indicates their clinical significance. A potassium of 3.3 sitting in a results table with no comment and no replacement meets none of those tests.

5Decision guide

When to assign E87.6, and when not to

The record says	Assign
Hypokalemia, no cause named	E87.6
Hypopotassemia or potassium deficiency	E87.6
Hypokalemic or familial periodic paralysis	G72.3 alone, never with E87.6
Hypokalemia with hyperemesis gravidarum	The obstetric code, per the category Excludes1
Hypokalemia in a newborn	The perinatal chapter code
Hypokalemia with congenital adrenal hyperplasia	E25.0, per the block Excludes1
Hypokalemia due to Bartter's syndrome	E26.81, with E87.6 reportable alongside
Hypokalemia due to a diuretic or other drug	E87.6 with the adverse effect code
Hypokalemic metabolic alkalosis	E87.6 and E87.3, since both are documented
Hypokalemia with hypomagnesemia	E87.6 and E83.42
Hyperkalemia	E87.5
Low potassium on labs, with no diagnosis stated	Query, since a finding is not a diagnosis

There is no sequencing rule attached to E87.6. The questions are whether an inherited exclusion displaces it, and whether the record supports reporting it at all.

Query rather than default when the note describes episodic weakness or paralysis, records a low potassium the assessment never mentions, or names a diuretic without connecting it to the result.

6Tabular list

Instructional notes at E87.6 and above

Note	Content
Inclusion term at E87.6	Potassium deficiency
Excludes1 at E87	Familial periodic paralysis (G72.3)
Excludes1 at E87	Diabetes insipidus (E23.2)
Excludes1 at E87	Electrolyte imbalance associated with hyperemesis gravidarum (O21.1)
Excludes1 at E87	Electrolyte imbalance following ectopic or molar pregnancy (O08.5)
Excludes1 at E87	Metabolic acidemia in newborn, unspecified (P19.9)
Excludes1 at E70 to E88	Congenital adrenal hyperplasia (E25.0), Marfan syndrome (Q87.4-), androgen insensitivity syndrome (E34.5-), and others
Excludes1 at E00 to E89	Transitory endocrine and metabolic disorders specific to newborn (P70 to P74)

Every note reaching this code is an Excludes1, so every one is a prohibition rather than a permission. Nothing on this list may be reported alongside E87.6.

That has a practical consequence worth stating. A coder verifying E87.6 by opening the code entry alone will see an inclusion term and nothing else, and will conclude the code is unconstrained. The exclusions are real; they are enforced by claim edits, and they are one and two levels up the hierarchy. Verify the category and block lines, not just the code.

The synonym lists attached to this code carry a separate trap. They include Verner-Morrison syndrome, which is a hormone-secreting tumor. The chapter note directs that all neoplasms are classified in Chapter 2, so a documented VIPoma is coded as a neoplasm, with the electrolyte disturbance reported additionally rather than instead.

7Comparison

Codes frequently confused with E87.6

Code	Descriptor	Use instead when
E87.5	Hyperkalemia	Potassium is elevated rather than reduced
E87.1	Hypo-osmolality and hyponatremia	The abnormality is sodium, reportable alongside E87.6
E87.0	Hyperosmolality and hypernatremia	Sodium is elevated
E87.3	Alkalosis	Alkalosis is documented, commonly with hypokalemia and reportable alongside it
E87.2-	Acidosis, subdivided into acute and chronic metabolic acidosis and other	An acidotic state is documented
E87.4	Mixed disorder of acid-base balance	More than one acid-base disturbance is documented
E87.7-	Fluid overload, including transfusion-associated circulatory overload	Volume excess is the diagnosis
E87.8	Other disorders of electrolyte and fluid balance, not elsewhere classified	The disturbance has no dedicated code
E83.42	Hypomagnesemia	Magnesium is low, reportable alongside E87.6
E86.0, E86.1	Dehydration and hypovolemia	Volume depletion is documented
G72.3	Familial periodic paralysis	Periodic paralysis is documented, which the Excludes1 blocks
E26.81	Bartter's syndrome	Bartter's syndrome is documented as the underlying cause
E26.0-	Primary hyperaldosteronism	Aldosterone excess is documented as the cause
E23.2	Diabetes insipidus	Diabetes insipidus is documented, which the Excludes1 blocks
E25.0	Congenital adrenal hyperplasia	The disorder is congenital adrenal hyperplasia
P70 to P74	Transitory endocrine and metabolic disorders specific to newborn	The patient is a newborn

The E83.42 row deserves attention. Hypomagnesemia and hypokalemia carry no exclusion against each other; they frequently occur together, and hypokalemia that resists replacement is often magnesium-dependent. A record documenting both supports two codes.

8Claim context

Services commonly reported with E87.6

E87.6 supports evaluation and management across every setting, along with the laboratory work that identifies and tracks it. Basic and comprehensive metabolic panels, standalone potassium levels, magnesium levels, and ECGs are all routinely ordered against it, and oral or intravenous replacement follows.

Repeat testing is where documentation matters most. Serial potassium levels during a replacement course are ordinary care, but the record needs to connect each draw to a clinical question, such as a dose given, a symptom, or a medication change. A string of identical panels with no note explaining them invites review.

The drug relationship is the second pressure point. Diuretic-associated hypokalemia is extremely common, and when the record attributes the low potassium to a medication, the adverse effect code belongs on the claim alongside E87.6. Confirm the applicable local coverage determination before submitting serial laboratory testing.

9Denials

Coding errors that cause denials

Error	Correction
Reporting E87.6 with familial or hypokalemic periodic paralysis	Report G72.3 alone, since the Excludes1 prohibits the pair
Assuming E87.6 has no exclusions because none appear on the code line	Check the category, block, and chapter, where all five sit
Coding E87.6 from a potassium result the provider never addressed	Query, since abnormal findings are not coded without stated clinical significance
Dropping hypomagnesemia when both are documented	Report E83.42 alongside E87.6
Dropping alkalosis when hypokalemic alkalosis is documented	Report E87.3 alongside E87.6
Coding E87.6 for a newborn	Assign the perinatal chapter code
Missing the adverse effect code when a diuretic or other drug caused it	Add the adverse effect code alongside E87.6
Coding a synonym such as Verner-Morrison syndrome to E87.6	Code the neoplasm per the chapter note, with the electrolyte code additional
Reporting E87.6 as a secondary diagnosis with no evaluation or treatment documented	Report only when the condition met the reporting criteria for other diagnoses

10Sources

Where to verify E87.6

ICD-10-CM Official Guidelines for Coding and Reporting

The rule on abnormal findings and clinical significance, and the criteria for reporting other diagnoses

The ICD-10-CM Tabular List at E87, at the E70 to E88 block, and at the chapter head

The five Excludes1 notes reaching E87.6 from the category, block, and chapter, none of which appear on the code line

The ICD-10-CM Alphabetic Index at Hypokalemia, Depletion, and Deficiency

The terms routing to E87.6, including hypopotassemia and potassium depletion

The CMS ICD-10 code page

Current code files and the annual addenda

Laboratory NCD list

Confirms electrolyte and metabolic panel testing is not among the 23 national laboratory policies, so frequency limits are contractor-specific

Medicare Coverage Database

Search your contractor's determinations for metabolic panel and electrolyte testing frequency.

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Last reviewed August 2026

This page is a free reference for billing and coding teams and is not coding, legal, or clinical advice. Code selection depends on the documentation in the record and on the policy of the payer being billed. Verify every code, instructional note, and sequencing rule against the current ICD-10-CM files and the Official Guidelines for Coding and Reporting for the applicable date of service. ICD-10-CM is maintained by the CDC's National Center for Health Statistics and published by CMS. CPT is a registered trademark of the American Medical Association. TruCare is not affiliated with CMS, NCHS, the AHA, or the AMA.