Hypokalemia ICD-10 Code: A Complete Guide for Medical Coding
September 28, 2026
Hypokalemia is a common electrolyte abnormality that healthcare providers encounter in outpatient practices, emergency departments, hospitals, and specialty settings. While identifying a low potassium level may seem straightforward clinically, coding the condition correctly requires more than simply reviewing a laboratory result.
For medical coding purposes, the primary hypokalemia ICD 10 code is E87.6. However, accurate claim submission may also depend on the underlying cause of the potassium deficiency, associated symptoms, laboratory testing, electrocardiographic monitoring, treatment provided, and other conditions addressed during the encounter.
Incorrect diagnosis selection, unsupported laboratory testing, duplicate services, improper modifiers, or insufficient documentation can contribute to denials and delayed reimbursement.
This guide explains the hypokalemia ICD-10 code, related diagnosis codes, commonly associated CPT and HCPCS codes, laboratory testing, modifiers, documentation requirements, and common claim denial issues that doctors, hospitals, clinics, and other healthcare providers should understand.
What Is Hypokalemia?
Hypokalemia means that the level of potassium in the blood is too low. Potassium is a mineral that helps nerves send signals muscles to contract, kidneys to function and the heart to beat normally.
A blood test showing potassium below about 3.5 milliequivalents per liter is usually considered hypokalemia. How dangerous hypokalemia is depends on how the low levels developed the person’s overall health, any medications they are taking, heart health and other mineral imbalances.
Common causes of hypokalemia include losing potassium from the stomach or intestines losing it through the kidneys using drugs not eating enough potassium, vomiting, diarrhea, potassium moving into cells or problems with hormones or the kidneys.
Some people with hypokalemia have no symptoms all. You might not notice anything
When potassium is very low symptoms can include muscle weakness, muscle cramps, tiredness, racing heartbeat, paralysis or changes in heart rhythm. Severe hypokalemia can cause changes, on an ECG. May lead to serious heart rhythm problems.
In coding it is important that the physician clearly documents the diagnosis of hypokalemia. The condition should not be. Inferred just from the lab result. The diagnosis must be directly stated in the record.
What Is the ICD-10 Code for Hypokalemia?
The primary ICD-10 code for hypokalemia is E87.6.
| ICD-10-CM Code | Description |
|---|---|
| E87.6 | Hypokalemia |
E87.6 falls within the ICD-10-CM category covering disorders of fluid, electrolyte, and acid-base balance.
CDC classification materials identify E87.6 as hypokalemia, including potassium deficiency.
For encounters that happen from April 1 through September 30 2026 providers should use the FY 2026 ICD-10-CM files. Starting on October 1 2026 the FY 2027 ICD-10-CM code set will be in effect for encounters up, to September 30 2027. CMS has already made the October 1 2026 update files available.
Hypokalemia ICD 10 Code at a Glance
Diagnosis: Hypokalemia
ICD-10-CM: E87.6
Code type: Billable diagnosis code
Clinical meaning: Abnormally low serum potassium/potassium deficiency
E87.6 does not have any characters, for laterality or severity. So mild, moderate and severe hypokalemia do not get ICD-10-CM codes just because the potassium level is different.
The level of severity should still be written down because it can affect the choices a doctor makes how strong the treatment’s how often the patient is watched and what kind of care is provided.
Hypokalemia Severity and Clinical Documentation
A coding professional should not decide severity by looking at a potassium result. Still knowing clinical classifications helps providers write the patient’s condition more clearly.
A commonly used clinical approach describes hypokalemia approximately as:
| Potassium Level | General Clinical Classification |
|---|---|
| 3.0–3.4 mEq/L | Mild |
| 2.5–3.0 mEq/L | Moderate |
| Below 2.5 mEq/L | Severe |
Clinical references note that mild hypokalemia may produce few symptoms, whereas moderate or severe deficiency can cause muscle weakness, paralysis, respiratory complications, and ECG abnormalities.
The ICD-10-CM code remains E87.6, regardless of these severity categories.
A stronger clinical note might state:
“Hypokalemia, potassium 2.8 mEq/L, likely secondary to gastrointestinal losses from persistent vomiting. Potassium replacement initiated and repeat potassium ordered.”
This documentation is significantly more useful than simply writing:
“K 2.8.”
The first note establishes the diagnosis, suspected cause, clinical assessment, and management plan.
Common Causes of Hypokalemia
Hypokalemia can develop through several different mechanisms. Identifying the underlying cause can be important for both treatment and coding.
Gastrointestinal Potassium Loss
Vomiting and diarrhea are frequent causes of potassium depletion.
Persistent vomiting may contribute indirectly to renal potassium loss through volume depletion and metabolic alkalosis, while diarrhea can result in direct gastrointestinal potassium loss.
When documented and relevant to the encounter, the provider may report hypokalemia along with the appropriate gastrointestinal diagnosis.
Examples include:
| ICD-10-CM Code | Condition |
|---|---|
| E87.6 | Hypokalemia |
| R11.10 | Vomiting, unspecified |
| R11.2 | Nausea with vomiting, unspecified |
| R19.7 | Diarrhea, unspecified |
CMS coding resources identify R11.10 for unspecified vomiting and R19.7 for unspecified diarrhea.
Use the most specific diagnosis supported by the medical record rather than automatically reporting symptom codes for every patient with hypokalemia.
Diuretic-Associated Hypokalemia
Loop and thiazide-type diuretics can increase renal potassium loss.
A provider should document when a medication is believed to have contributed to the electrolyte abnormality.
For example:
“Hypokalemia likely secondary to chronic loop diuretic therapy.”
Do not automatically assign a drug-related diagnosis or adverse-effect code based solely on the patient’s medication list. The relationship between the medication and the condition should be established in the clinical documentation before drug-related coding rules are applied.
Renal Potassium Loss
Certain renal disorders can cause excessive potassium excretion.
Depending on the clinical situation, evaluation may include:
serum potassium,
serum magnesium,
serum creatinine,
acid-base evaluation,
urinary potassium,
urinary creatinine,
and other renal or endocrine testing.
The renal diagnosis should be reported only when documented and clinically established.
Intracellular Potassium Shift
Hypokalemia can also develop when potassium shifts from the extracellular space into cells.
Possible contributors include insulin administration, beta-adrenergic stimulation, alkalosis, and certain metabolic or endocrine conditions.
In these circumstances, E87.6 may be reported along with other documented conditions that explain the underlying mechanism.
Poor Potassium Intake
When you eat little it is a rare cause of low potassium because healthy kidneys can lower potassium excretion a lot. Yet not eating enough can add to the risk of hypokalemia, in people who lose potassium or have long‑term illnesses.
Providers should avoid assuming that a patient’s hypokalemia is caused by poor nutrition without clinical support.
Related ICD-10-CM Codes
There is no need to add diagnosis codes that do not relate to the condition just because those codes often appear with low potassium levels. Secondary codes must show conditions that were actually recorded checked, watched or handled.
Some potentially relevant codes include:
| ICD-10-CM Code | Description | Coding Consideration |
|---|---|---|
| E87.6 | Hypokalemia | Primary code for documented hypokalemia |
| E87.5 | Hyperkalemia | Do not confuse with hypokalemia |
| E87.3 | Alkalosis | Report when separately documented |
| E86.0 | Dehydration | May accompany fluid losses when documented |
| R11.10 | Vomiting, unspecified | Potential cause of potassium loss |
| R11.2 | Nausea with vomiting, unspecified | Use when supported |
| R19.7 | Diarrhea, unspecified | Potential GI potassium loss |
| R53.1 | Weakness | May be associated with significant hypokalemia |
| R00.2 | Palpitations | Report when clinically evaluated and documented |
Do not report symptoms separately when coding guidelines or payer rules consider them integral to a confirmed diagnosis unless the circumstances support separate reporting.
Hypokalemia vs. Hyperkalemia ICD-10 Coding
Hypokalemia and hyperkalemia are opposite electrolyte disorders and should not be confused during claim preparation.
| Condition | ICD-10-CM Code |
|---|---|
| Hypokalemia | E87.6 |
| Hyperkalemia | E87.5 |
Hypokalemia means there is not potassium in the blood. Hyperkalemia means there is much potassium in the blood.
Putting E87.5 and E87.6 in the order can cause problems. It might lead to clinical data, incorrect medical necessity checks or issues, during payer reviews. Getting the codes right matters a lot for patient care.
The diagnosis should always be reconciled against the physician’s assessment rather than selected from the laboratory value alone.
CPT Codes Commonly Associated With Hypokalemia
There is no single CPT code representing “hypokalemia treatment.” CPT coding depends on the actual service performed.
Commonly associated services include electrolyte testing, metabolic panels, magnesium testing, venipuncture, ECG services, evaluation and management, and repeat laboratory measurements.
Potassium and Metabolic Laboratory Codes
| CPT Code | Common Use |
|---|---|
| 84132 | Potassium measurement |
| 80048 | Basic metabolic panel |
| 80051 | Electrolyte panel |
| 80053 | Comprehensive metabolic panel |
| 80069 | Renal function panel |
| 83735 | Magnesium measurement |
| 36415 | Collection of venous blood by venipuncture |
CMS materials identify 84132 as a serum potassium assay and list 80048, 80051, 80053, and 80069 among commonly recognized laboratory panels.
CPT 84132 — Potassium
CPT 84132 may be appropriate when potassium is tested separately.
For example, a patient receiving potassium replacement may require follow-up potassium measurements to determine whether treatment is correcting the deficiency.
If potassium is already part of a metabolic or electrolyte panel done at the time reporting the potassium test, on its own can cause bundling issues.
It is important for providers to check panel rules and payer edits before billing component laboratory tests.
CPT 80048 — Basic Metabolic Panel
A basic metabolic panel offers information about potassium and, about clinically relevant chemistries.
It may be ordered when evaluating disturbances that involve potassium, kidney function, dehydration, medication effects or metabolic abnormalities.
Because potassium is part of the panel separately reporting CPT 84132 for the specimen and testing session may not be appropriate unless a legitimate separately reportable repeat test was performed. Potassium is already measured in the panel. A separate CPT 84132 code may be unnecessary.
CPT 80051 — Electrolyte Panel
The electrolyte panel measures important electrolytes and is often used when the main goal is to check the body’s electrolyte balance.
CMS lists 80051, as a blood test panel that includes sodium, potassium, chloride and carbon dioxide.
CPT 80053 — Comprehensive Metabolic Panel
A comprehensive metabolic panel may be ordered when the provider requires broader information about electrolyte, renal, hepatic, and metabolic status.
It should not automatically be ordered or coded simply because the patient has hypokalemia. The documentation and services performed must support the test.
CPT 83735 — Magnesium
Magnesium testing can be clinically relevant because magnesium deficiency may coexist with potassium abnormalities and can complicate correction of hypokalemia.
CMS laboratory coding materials recognize CPT 83735 for magnesium testing.
Documentation should demonstrate why magnesium testing was medically reasonable and necessary for the patient.
ECG CPT Codes for Patients With Hypokalemia
Moderate or severe hypokalemia can affect cardiac electrical activity.
Potential ECG findings include T-wave flattening, ST-segment changes, prominent U waves and other rhythm abnormalities. Serious potassium deficiency can increase the risk of arrhythmias.
Depending on the service provided, ECG codes may include:
| CPT Code | Service |
|---|---|
| 93000 | Routine 12-lead ECG including tracing, interpretation, and report |
| 93005 | ECG tracing only |
| 93010 | ECG interpretation and report only |
The code selected should match the actual service furnished.
For example, a hospital may own and produce the ECG tracing while the physician separately performs the interpretation. In that situation, the billing arrangement differs from an office in which the physician practice provides the complete ECG service.
Hypokalemia does not automatically justify an ECG for every patient. The patient’s potassium level, symptoms, cardiac risk factors, medications, and clinical condition should support the medical necessity of the service.
E/M Coding for Hypokalemia Encounters
Hypokalemia may be managed during outpatient, inpatient, observation, or emergency care.
Applicable E/M codes depend on the setting and level of service.
Common office/outpatient families include:
99202–99205 for new patients
and
99211–99215 for established patients.
Emergency department and hospital E/M families may apply when the patient is managed in those settings.
Providers should select the E/M level based on the applicable CPT requirements, including medical decision-making or time when permitted.
A low potassium level alone does not determine the E/M level.
Factors that may contribute to medical decision-making can include:
severity of potassium deficiency,
review of laboratory results,
presence of symptoms,
cardiac risk,
medication management,
decision regarding oral versus intravenous replacement,
repeat laboratory monitoring,
evaluation of renal function,
assessment of the underlying cause,
and consideration of emergency or inpatient treatment.
HCPCS Code for Potassium Chloride
One HCPCS Level II code that may be relevant in certain treatment settings is:
J3480 — Injection, potassium chloride
CMS HCPCS materials identify J3480 for injectable potassium chloride.
The correct units, drug quantity, route, setting, payer policy, and coverage requirements must be reviewed before submission.
Providers should not assume that supplying potassium automatically makes J3480 separately reimbursable. Facility payment methodology, bundled services, payer-specific drug rules, and the place of service can affect reimbursement.
CMS also publishes quarterly HCPCS updates, so practices should verify the code set applicable to the date of service.
Modifiers Commonly Relevant to Hypokalemia-Related Claims
Modifiers should never be appended simply to force payment through a payer edit.
They communicate specific circumstances surrounding a service and require documentation.
Modifier 91 — Repeat Clinical Diagnostic Laboratory Test
Modifier 91 is especially important when managing hypokalemia because potassium may need to be measured several times during the same day.
CMS explains that modifier 91 may be appropriate when the same laboratory test must be repeated on the same date to obtain subsequent medically necessary results.
For example:
A patient presents with severe hypokalemia.
An initial potassium measurement is obtained.
Potassium replacement is administered.
Several hours later, another potassium measurement is medically necessary to determine the response to therapy.
When payer requirements are satisfied, the repeat laboratory service may warrant modifier 91.
Do Not Use Modifier 91 For:
rerunning a test because of an equipment malfunction,
retesting because the original specimen was inadequate,
confirming a laboratory result when only one reportable result was required,
or bypassing a payer edit without a medically necessary repeat test.
CMS specifically states that modifier 91 is intended for legitimate repeat clinical laboratory measurements, not simple confirmation or correction of testing problems.
Modifier 59 — Distinct Procedural Service
Modifier 59 identifies certain services that are distinct from other services performed on the same date.
CMS emphasizes that modifier 59 should not be used routinely to bypass NCCI edits. Documentation must demonstrate that the service was truly separate under applicable coding rules.
For straightforward repeat potassium monitoring, modifier 91 is generally more directly relevant than modifier 59 when the circumstances satisfy the definition of a repeat clinical diagnostic laboratory test.
XE, XP, XS, and XU Modifiers
CMS created the X modifiers to provide more specific information in situations historically reported with modifier 59:
XE — Separate encounter
XP — Separate practitioner
XS — Separate structure
XU — Unusual non-overlapping service
CMS encourages use of the more descriptive modifier when it accurately explains why services are distinct.
These modifiers should be used only when supported by the clinical circumstances and payer rules.
Modifier 25
Modifier 25 may be appropriate when a significant, separately identifiable E/M service is performed by the same practitioner on the same date as another procedure or service.
CMS NCCI guidance recognizes modifier 25 in appropriate E/M circumstances.
A provider should not automatically attach modifier 25 whenever laboratory or procedural services occur during an office visit. The documentation must support a distinct E/M service.
Documentation Requirements for Hypokalemia Coding
Good documentation should explain the patient’s condition rather than simply repeat the laboratory result.
A complete note may address:
Diagnosis: Clearly state hypokalemia when clinically diagnosed.
Potassium level: Document the relevant laboratory findings.
Symptoms: Record weakness, cramps, palpitations, fatigue, gastrointestinal symptoms, or other clinically relevant findings.
Suspected cause: Document vomiting, diarrhea, diuretics, renal loss, endocrine disease, medication effects, nutritional factors, or other causes when established or suspected.
Medication review: Identify medications that influence potassium when relevant.
Associated electrolyte abnormalities: Document clinically significant magnesium, sodium, acid-base, or other abnormalities.
Treatment: Record oral or intravenous potassium replacement and other interventions.
Monitoring: Explain why repeat potassium testing or ECG monitoring is required.
Follow-up: Document plans for repeat labs, medication changes, referrals, or higher-level care.
For coding purposes, documentation should establish the medical necessity for the services billed.
Can E87.6 Be the Primary Diagnosis?
Yes.
E87.6 can be the primary diagnosis when hypokalemia is chiefly responsible for the encounter and the documentation supports that conclusion.
For example, a patient may be referred to an emergency department after a critical potassium result. If the principal purpose of the encounter is assessment and treatment of hypokalemia, E87.6 may be appropriately positioned as the primary diagnosis for that professional claim, subject to setting-specific coding rules.
However, if hypokalemia occurs secondary to another condition that is chiefly responsible for the encounter, sequencing may differ.
The correct order depends on the clinical circumstances, coding guidelines, setting, and payer requirements.
Common Hypokalemia Claim Denials
Correctly coding E87.6 does not guarantee payment. Denials frequently occur because of the relationship between diagnosis coding, laboratory testing, medical necessity, modifiers, and documentation.
1. Medical Necessity Not Supported
A payer may deny repeated electrolyte or metabolic testing when the documentation does not explain why multiple tests were required.
Prevention
Document:
the abnormal potassium level,
severity,
treatment,
medications,
clinical symptoms,
and the reason repeat testing was necessary.
2. Duplicate Laboratory Service
Repeat potassium tests performed on the same day can appear to the payer as accidental duplicates.
Prevention
When appropriate, report the legitimate repeat laboratory service according to payer rules and use modifier 91 when its requirements are satisfied.
Documentation should clearly identify different collection times and the clinical reason for repeat testing.
3. Incorrect Modifier 91
Modifier 91 can itself create problems if used merely to rerun an unsuccessful specimen or confirm an initial result.
CMS specifically limits modifier 91 to clinically necessary repeat laboratory tests performed to obtain subsequent results.
4. Separate Billing of Panel Components
A practice may perform a metabolic panel and then improperly bill each component separately.
CMS NCCI policy requires providers to consider laboratory panel rules when multiple components are performed.
Prevention
Determine whether the tests performed meet the requirements of an established laboratory panel before individually coding component tests.
5. Diagnosis Does Not Match Documentation
The claim reports E87.6 even though the physician only documented “low potassium lab.”
Coding should be based on the provider’s documented clinical diagnosis in accordance with applicable coding rules.
Prevention
Encourage clear assessment statements such as:
“Hypokalemia”
rather than relying solely on the laboratory report.
6. Incorrect Diagnosis Code
E87.5 and E87.6 are easily confused.
Remember:
E87.5 = Hyperkalemia
E87.6 = Hypokalemia
A single-digit error changes the diagnosis from low potassium to high potassium.
7. Unbundling Laboratory Services
Reporting 84132 separately when potassium was already included in a metabolic panel from the same testing session can create an edit or denial.
Prevention
Review laboratory panel requirements, NCCI edits, payer policies, and the actual testing sequence before submitting individual component codes.
8. Unsupported ECG
An ECG performed for a patient with a minor asymptomatic potassium abnormality may be questioned if the medical record contains no explanation of cardiac concern.
Prevention
Document clinical factors such as:
significant hypokalemia,
palpitations,
cardiac disease,
arrhythmia risk,
relevant medication use,
ECG abnormalities,
or other reasons supporting the service.
9. Invalid or Outdated Codes
ICD-10-CM and HCPCS code sets are regularly updated.
CMS notes that ICD-10-CM files applicable beginning October 1, 2026 are part of the FY 2027 code set, while HCPCS receives quarterly updates.
Providers should validate codes against the version applicable to the actual date of service.
Hypokalemia Coding Checklist
Before submitting a claim involving hypokalemia, verify that:
E87.6 is supported by the provider’s documentation.
The potassium abnormality has been clinically assessed rather than simply copied from a laboratory report.
The suspected or confirmed underlying cause is documented when known.
Any secondary diagnosis codes are supported by the medical record.
The CPT code reflects the laboratory panel or individual test actually performed.
Component tests have not been improperly unbundled from a panel.
Repeat laboratory testing has documented medical necessity.
Modifier 91 is used only for a legitimate medically necessary repeat clinical diagnostic laboratory test.
Modifier 59 or an X modifier is not being used merely to bypass an edit.
ECG services are supported by the patient’s clinical condition.
Drug or infusion coding accurately reflects the substance, quantity, route, and setting.
Current payer coverage rules and NCCI edits have been reviewed.
Frequently Asked Questions About Hypokalemia ICD 10 Coding
What is the ICD-10 code for hypokalemia?
The ICD-10-CM code for hypokalemia is E87.6. It represents documented potassium deficiency or abnormally low blood potassium.
Is E87.6 a billable ICD-10 code?
Yes. E87.6 is used to report hypokalemia when the condition is appropriately documented.
Is there a separate ICD-10 code for severe hypokalemia?
There is not a separate E87.6 subcode based solely on mild, moderate, or severe potassium levels. Clinical severity should still be documented because it can affect treatment and medical decision-making.
What is the difference between E87.5 and E87.6?
E87.5 represents hyperkalemia, meaning elevated potassium.
E87.6 represents hypokalemia, meaning decreased potassium.
What CPT code is used for a potassium blood test?
CPT 84132 may be used for a potassium assay when it is separately reportable. Potassium is also included in several laboratory panels, including common metabolic and electrolyte panels.
What CPT code is used for a basic metabolic panel?
CPT 80048 represents a commonly used basic metabolic panel containing total calcium and other chemistry measurements, including potassium.
Can modifier 91 be used for repeat potassium testing?
Potentially, yes. Modifier 91 may be appropriate when the same laboratory test is medically necessary more than once on the same day to obtain subsequent results used in patient treatment or management.
It should not be used merely because a test was repeated due to an equipment or specimen problem.
Can hypokalemia cause ECG abnormalities?
Yes. Moderate and severe hypokalemia may produce T-wave changes, ST depression, prominent U waves, and clinically significant arrhythmias.
Should vomiting or diarrhea be coded with hypokalemia?
They may be reported when they are documented, clinically relevant, and separately reportable. Do not automatically add symptom codes simply because they are possible causes of potassium deficiency.
Final Thoughts on Hypokalemia ICD-10 Coding
The correct hypokalemia ICD 10 code is E87.6, but accurate coding does not end with selecting that diagnosis.
Healthcare providers should document why the potassium level is abnormal, what clinical consequences are present, what caused or contributed to the condition, what testing was required, and how the patient was treated.
Laboratory services such as 84132, 80048, 80051, 80053, 80069, and 83735 may be relevant depending on the clinical evaluation. ECG services may also be appropriate when cardiac monitoring is medically necessary. In certain settings, injectable potassium chloride may involve HCPCS J3480.
Repeat potassium testing deserves particular attention. When a medically necessary potassium test is repeated on the same date to evaluate the patient’s response to treatment, modifier 91 may be appropriate. It should not be used simply to overcome a duplicate-test denial.
The strongest claims are those in which the diagnosis, laboratory findings, medical necessity, treatment, CPT/HCPCS coding, modifiers, and clinical documentation tell the same story.
For every claim involving hypokalemia, verify the applicable ICD-10-CM version, current CPT and HCPCS information, CMS NCCI edits, Medicare Administrative Contractor requirements, and commercial payer policies for the patient’s date of service.
