Do you need the ICD-10 code for hypokalemia? The U.S. code is E87.6 – Hypokalemia. The code is straight forward. Identifying when to report the code takes a slightly deeper analysis of the clinical documentation.
This guide provides the reasoning for the decisions made with documentation tips, comparisons of relevant codes and provisions, and three examples worked out in detail. The code and the inclusion term were checked against the most current provisions and codes at the time of writing this guide.
E87.6 at a Glance
| Item | Coding reference |
|---|---|
| Code | E87.6 |
| Official descriptor | Hypokalemia |
| Inclusion term | Potassium deficiency |
| Classification | U.S. ICD-10-CM |
| Parent category | E87: Other disorders of fluid, electrolyte and acid-base balance |
| Complete diagnosis code? | Yes; no additional characters are required |
| Separate acute, chronic, or severe code? | No |
| Opposite potassium disorder | E87.5, hyperkalemia |
Code is “billable” when it’s at a point of completion to be reported on an applicable claim. It does not mean that all services related to that diagnosis are covered or payable.
Which Code Year Applies?
FY2027 started on October 1, 2026. Beginning with the outpatient release most applicable to the outpatient encounter date or the inpatient release most applicable to the inpatient discharge date, including subsequent revisions. A claim submitted in October for an earlier encounter does not necessarily use the October code set.
Keep the date question and the code question separate. The fact that E87.6 is unchanged does not make an older codebook the correct reference for all other diagnoses on the claim. For international readers, local ICD modifications and reimbursement policy may vary from U.S. ICD-10-CM.
What Hypokalemia Means Clinically
Hypokalemia is when the potassium level in the blood is below 3.5 mEq/L. Potassium helps nerves and muscles to work properly, and helps the heart to function normally. The more serious a low potassium level is, depends on the potassium level itself, the signs and symptoms of the patient, the speed the level dropped, and other health conditions the patient may have.
There are many reasons for potassium levels to go down, these may be vomiting, diarrhea, renal potassium loss, and other loss of fluid and potassium, movement of potassium into cells and poor dietary intake. There are hormonal and renal disorders that may be a factor as well. Diuretics decrease the levels of potassium. When diarrhea is associated with hypokalemia, choosing the correct ICD-10 code for diarrhea would depend on the assessment of the provider, as well as if there is an underlying condition that is causing the diarrhea. A low potassium level may be due to many factors. Medication may be a factor as well, however, for certainty, clinical information must support this.
Symptoms and Urgent Warning Signs
There are no symptoms at all with mild hypokalemia. With more severe hypokalemia, patients can be weak, get cramps or experience constipation and/or palpitations. Potassium is important for normal heart function and potassium depletion can cause abnormal heart rhythms and heart function. Symptoms are not always present and are not very specific to hypokalemia. Diagnosis is always made by the laboratory.
Signs and symptoms often times lead to further testing to evaluate the level of severity. A potassium level of 2.5 mEq/L or less with abnormal ECG or neurological symptoms is considered an emergency. If patient’s experience fainting, severe weakness, have great difficulty breathing and/or have other abnormal and concernly irregular heart rhythms, they need to be evaluated and treated as an emergency. The number alone does not determine the level of emergency.
Related ICD-10-CM Codes: Check the Electrolyte
Some conditions share similar appearances. Described below are shortened versions of code descriptions for quick comparison. Verify the complete Tabular List information before using the code descriptions.
| Code | Condition or category | Key distinction |
|---|---|---|
| E87.6 | Hypokalemia | Low potassium |
| E87.5 | Hyperkalemia | High potassium, not low potassium |
| E87.1 | Hypo-osmolality and hyponatremia | Low sodium |
| E83.42 | Hypomagnesemia | Low magnesium |
| E87.2 | Acidosis category | Requires a complete code below the category |
| E87.20 | Acidosis, unspecified | Not established by a low bicarbonate result alone |
| E87.21 | Acute metabolic acidosis | Use when this diagnosis is documented |
| E87.22 | Chronic metabolic acidosis | Check its underlying-etiology instruction |
| E87.3 | Alkalosis | A different acid-base disorder |
| E87.7 | Fluid overload category | Not hyperkalemia; select the appropriate complete code |
| E87.8 | Other electrolyte/fluid-balance disorders, NEC | Not a substitute for documented hypokalemia |
E83.40 and E83.49 do not relate to potassium metabolism. Thus, they cannot be used as a potassium fallback. Likewise, a low bicarbonate level alone does not allow a coder to make a diagnosis of acidosis. These distinctions follow the logic of classification and are not explicit in the classification.
When Should You Assign E87.6?
When assessing a claim, always review the provider assessment first and the lab results second. Although a lab result and a diagnosis are closely related, they are not equivalent pieces of documentation.
A Practical Five-Step Review
Establish the setting and date, identify the claim type and code release, find the diagnostic statement, review the assessment and progress notes and final documentation, check reportability and determine relevance to the current stay, review exceptions and sequencing, consider drug effects, pregnancy and the perinatal period, inherited and other exclusions, and reconcile the claim.
This is not an additional official reporting requirement; this workflow is intended to bring omissions to your attention before claim submission.
Can You Code Hypokalemia From a Lab Result Alone?
There are situations where an abnormal potassium level is ordered, and the provider has indicated on the assessment that hypokalemia is present. Although there is an abnormal lab result, you cannot independently diagnose based on the lab result. In this case, you would take the assessment into account and review the documentation for the clinical significance. In the outpatient setting, documentation is generally more thorough. This does not mean that the coder becomes the diagnosing clinician.
If “low K” is documented by the provider, read the documentation in full to review the context, and check the indexed terminology. It is not the same as a potassium result being flagged in a lab. When a lab result is flagged, you should not automatically convert the result to E87.6.
Documentation That Makes the Coding Decision Clear
Good documentation tells what the clinician concluded and what happened next. It allows a peer to understand the clinical situation without needing to piece together the information from orders that may or may not be in the correct sequence.
| Record element | Useful detail |
|---|---|
| Assessment | Hypokalemia, with relevant current status |
| Supporting results | Potassium value, units, date, and meaningful trend |
| Clinical context | Symptoms, pertinent negatives, and relevant findings |
| Cause | Known cause, documented drug relationship, or ongoing evaluation |
| Management | Replacement, medication review, further evaluation, or monitoring |
| Follow-up | Planned reassessment and response to care |
These prompts are more practical than six universally mandatory fields. An asymptomatic patient could present with reportable hypokalemia. Absence of an ECG, prescription, or known cause does not in itself invalidate the diagnosis of the provider making the report.
Useful Note Versus Incomplete Note
Incomplete for a clear coding decision: “K 3.2. Repeat BMP.”
More Informative if Accurate: “Hypokalemia; potassium 3.2 mEq/L. No reported weakness or palpitations. Medication history reviewed; cause not yet established. Repeat testing to reassess potassium level.”
The second example relates the result to a clinical conclusion. It does not suggest (that is, invent) symptoms, or list a possible cause (that is, a medication). It also does not present an order to treat the condition (i.e. the diagnosis) as the diagnosis.
Nurses and other clinical staff members provide symptom and historical information. Coders review and classify the information to determine a diagnosis. Hypokalemia must be established by a qualified and legally accountable individual; job titles do not determine that in every case.
When clarification is needed, use the organization’s approved, non-leading query process. Determine what the finding represents, and give clinically reasonable responses. Do not request a diagnosis simply to determine payment.
Outpatient, Observation, and Inpatient Coding
The code may remain E87.6 while the reporting rules change with the setting.
| Setting | Handling an uncertain diagnosis |
|---|---|
| Office, ED, and hospital outpatient/observation | Do not report “possible” or “rule-out” hypokalemia as confirmed; report the supported reason for care at the highest certainty available |
| Qualifying inpatient hospital facility discharge | A qualifying uncertain diagnosis documented at discharge may be coded as established under inpatient guidance |
Observation is outpatient care for this purpose. Do not apply the inpatient facility discharge rule to every claim merely because the patient occupied a hospital bed.
First-Listed, Principal, or Additional Diagnosis?
Outpatient coding requires selection of the condition for which services were primarily rendered. Inpatient facility coding requires selection of the principal diagnosis established after study to be the most responsible for the admission, subject to applicable sequencing rules. Other diagnoses reported must meet the reporting criteria.
There is no hard and fast rule about placement of E87.6. In certain cases, the underlying condition may be coded before E87.6. For example, in the case of a visit with major reason of vomiting and where the admission was primarily for correction of hypokalemia, one may be led to code the hypokalemia first. There are also cases where the entire record is a bowl of spaghetti and requires judgment in coding. Read the entire record and use your judgment.
Do not expect an increase in the MS-DRG payment just because the patient has a potassium level. E/M service selection depends on service criteria. Same is true for inpatient grouping.
Excludes1 and Excludes2: Read the Parent Notes
E87.6 is short, but instructions inherited from above still make a difference. A code-only lookup can hide those instructions.
Excludes1 Notes Under E87
The parent category E87 contains Excludes1 notes for the following conditions:
| Excluded condition | Referenced code |
|---|---|
| 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 |
| Unspecified metabolic acidemia in a newborn | P19.9 |
E87.6 is an example of what not to do. Do not report both E87.6 and O21.1, for example. P19.9 is listed under E87, but it should not be used as a replacement code for hypokalemia in the newborn.
Generally, Excludes1 means the excluded condition should not be reported with the code it is listed under. If the conditions are not related, Excludes1 does not need to be used. If the relationship is not clear, query. Different from Excludes1, Excludes2 means both conditions can be coded.
Is There an E87.6-Specific Excludes2 Note?
The reviewed FY2027 E87.6 entry does not have an Excludes2 note of its own. Do not take an Excludes2 note from one of its neighboring codes and apply it to hypokalemia. For example, E87.0 has a condition-specific note of its own.
The principle here is to check the exact entry and its ancestors, and resolve any conflicts. A patient having two conditions is not enough to warrant the exclusion of both codes.
Drug Effects, Pregnancy, and Other Special Situations
Medication-Induced Hypokalemia
For an adverse effect of a properly administered medication, sequence the nature of the effect before the applicable drug adverse-effect code. Sequence the effects of poisoning prior to the applicable poisoning code.
Examples of active treatment, when supported by the record, would include E87.6 with T50.1X5A for an adverse effect of a loop diuretic or T50.2X5A for an adverse effect of thiazide or other applicable diuretics. Verify the exact medication using the drug table, and then the Tabular List. The “A” character indicates active treatment and is not related to the first calendar visit.
This order does not always apply, and in the case of E87.6 controlling the principal diagnosis, for example, the pertinent guidance of obstetrics would govern drug events occurring during pregnancy.
Pregnancy and Newborns
A complication of pregnancy that is documented as hypokalemia would generally require the applicable obstetric code prior to E87.6. If O99.28- is more appropriate, then its applicable pregnancy, childbirth, or puerperium code should be assigned, with gestational week information added if available. Do not use this route to avoid a more specific obstetric classification.
O21.1 applies to qualifying cases of hyperemesis gravidarum with metabolic disturbance; its inclusion terms state onset occurs before the end of the 20th week. Consider the context of the pregnancy as well as the timing and the diagnosis of the case to determine if it is appropriate to assign to a pregnant woman who is merely vomiting.
As for hypokalemia of the newborn, please see Chapter 16 and P74.32. The use of perinatal codes depends on the situation; this should not be considered an automatic switch to E87.6 at the time of birth.
Coexisting Hypomagnesemia
E83.42 may be assigned with E87.6 to report both conditions, if they are documented and reportable. Do not infer either condition from magnesium supplementation. Maintain each assessment and management for a given condition, especially if the care team is evaluating other electrolyte imbalances.
Three Practical Coding Examples
The following cases are illustrative only, and are not actual patient records, treatment recommendations, or evidence of payment of claims. Coding choices are based on the stated facts and no conflicting instructions.
Scenario 1: An Abnormal Lab Result Becomes a Diagnosis
An adult has a potassium of 3.2 mEq/L during an office visit. The clinician documents hypokalemia, considers potential causes, and orders further testing. The patient reports no symptoms, and a cause has not been determined.
Decision: Hypokalemia is a documented condition, and E87.6 should be assigned. It is not necessary to create an extension to “unspecified hypokalemia” or a drug adverse effect or the symptoms the patient did not have. Code placement varies based on the reason for the encounter.
What changes the answer: If all the clinician had was a potassium flag, and there was not any documented hypokalemia, the coder would be unable to assign a code based on an assumed diagnosis, because an unconfirmed diagnosis is different than an unknown cause.
Scenario 2: Hypokalemia Due to the Appropriate Use of a Loop Diuretic
An adult is being treated for hypokalemia due to the diuretic furosemide, which the provider believes caused the hypokalemia based on the patient report of taking the diuretic as prescribed. The provider documents the adverse effect of the diuretic and the management plan.
Decision: The adverse effect of the diuretic and the hypokalemia are both conditions. The adverse effect of a drug is reported with T50.1X5A, and E87.6 is reported prior. Other relevant conditions are reported based on the conditions of the encounter. It is not appropriate to replace the code for the loop diuretic with a code for a different drug class.
What changes the answer: Furosemide can cause hypokalemia, but an undocumented medication list doesn’t justify an adverse effect. Something lower on the list (like a documented overdose) would be higher on the priority list.
Scenario 3: Hyperemesis With Included Electrolyte Disturbance
A patient at 11 weeks of pregnancy is seen for evaluation of hyperemesis, which has been occurring since earlier in her pregnancy. The provider documents hyperemesis gravidarum with a metabolic disturbance, including hypokalemia.
Decision: O21.1 captures that documented obstetric condition. Do not add E87.6 for the same included electrolyte disturbance. Other supporting information, like weeks of gestation, can be documented and added when appropriate.
What changes the answer: Hypokalemia from a different, separate process would require a new assessment, exclusion exception, and obstetric rules. The presence of pregnancy does not mean every case of low potassium is the same.
Laboratory and Service Billing: Diagnosis Is Not Coverage
E87.6 is the ICD-10-CM code for Hypokalemia. Evaluate the service and supply codes provided by CPT and HCPCS to identify the level of service and supply rendered. If your team handles Laboratory Billing Services, the claim process begins with ensuring the documented diagnosis is consistent with the reason for test provided by the order. The claim must be consistent with the payer’s editing, coding, and billing requirements.
Potassium can be measured by itself with CPT 84132 or as part of an electrolyte panel (80051), a basic metabolic panel (80048), or a comprehensive metabolic panel (80053). Choose the service code that describes the service performed, and that meets the applicable CPT definition.
A Component of a Panel is Not a Separate Test
A component of a panel may not be charged as a separate test. For example, if a potassium component of a panel is ordered and performed, a repeat test of potassium that is performed later in the day would not be considered a prohibited test, since an earlier panel test included potassium. The modifiers designated by the NCCI are interpretation aids and should not be indiscriminately assigned. Each case must be evaluated for the nature of the service and payer rules.
A record of the original order, collection time of the components of the panel, the reason for reassessment and collection time of the subsequent order, are some of the elements that would assist in determining if a repeat test of a component of a clinical service was performed. A modifier should only be assigned if the payer rules and the nature of the service support the assignment.
An Infusion Record is Not A Complete Record
A diagnosis code by itself does not support completion of a record. The monitoring and related documentation should support the administration and infusion of the product. An undiluted concentrated potassium chloride solution is not to be administered by direct IV-push. A CPT code for a potassium infusion should not be used to support a routine potassium replacement.
Treatment, Follow-Up, and Resolved Episodes
Treatment includes intravenous or oral potassium supplementation, clinician-directed adjustment of medication, and management of the illness that is contributing to the hypokalemia. The route and type of monitoring of a patient receiving treatment for hypokalemia depends upon the clinical situation. Patients should not adjust their medication, stop taking their medication, or take potassium supplements because of a code lookup.
For documentation review, consider three situations: an active episode, a chronic condition that is mostly controlled by treatment, and a condition that has been fully resolved. A normal result during treatment of a condition is not always an indicator that the condition has fully resolved.
A chronic condition that has been fully resolved should not be reported using the “E87.6” additional diagnosis code. Hypokalemia that is present on admission, and was reported during the stay, should not be reported as a separate condition just because it was resolved by treatment and the patient was discharged. The appropriate currently-present condition and/or additional diagnosis codes should be reported.
A Pre-Submission Check for E87.6
- Check the claim date, setting, and code set version.
- Match to the provider’s diagnosis when assigning code E87.6. An automated lab flag would not warrant assigning E87.6.
- Ensure the record is referring to low potassium and not hyperkalemia or low magnesium.
- Review inherited exclusions and any pregnancy, perinatal or drug-related instructions.
- Confirm additional conditions are reportable and that sequencing is justified.
- Review the details of the laboratory panels and test repetition, as well as the circumstance of testing and drug administration.
- Verify specific service coverage, without assuming a diagnosis indicates payment.
When a claim is denied, verify the actual reason for denial on the remittance advice. Compare the denied claim to the original record. If coverage is not indicated, a corrected claim may be warranted. If lack of coverage is indicated, an appeal based on policy may be warranted. Neither justifies the addition of unsupported codes nor the enhancement of clinical documentation.
Frequently Asked Questions
What Is the ICD 10 for Hypokalemia?
In U.S. ICD-10-CM, E87.6 identifies hypokalemia. It is a complete diagnosis code for applicable documented cases. Always review the encounter’s reporting requirements and relevant exclusions before assigning it.
Is E87.6 a Billable Code?
Yes. E87.6 is a complete code, but billable status is not a coverage guarantee. Payment also depends on the documented services, medical necessity, payer policy, and other claim requirements.
Is There a Different Code for Acute or Severe Hypokalemia?
No. Acute, chronic, mild, moderate, and severe hypokalemia do not have separate E87.6 subcodes. Record clinically relevant severity and duration in the documentation rather than adding nonexistent code characters.
Can a Coder Assign E87.6 From a Low Potassium Result?
Not by independently diagnosing the patient from that result. Review the provider’s assessment and applicable reporting rules. Seek clarification when the record does not establish what the abnormal finding means.
Can Hypokalemia and Hypomagnesemia Be Coded Together?
Yes, when both conditions are documented and meet reporting requirements. E87.6 describes hypokalemia; E83.42 describes hypomagnesemia. Potassium or magnesium replacement orders alone do not establish both diagnoses.
Should E87.6 Be Used With Hyperemesis Gravidarum?
Do not add E87.6 for the electrolyte disturbance included in O21.1. A genuinely unrelated condition requires separate review of the Excludes1 exception, clinical documentation, and applicable pregnancy guidance.
The Bottom Line
Hypokalemia is usually coded E87.6, but to submit the code correctly, there are other factors to take into account besides locating the number. Confirm the provider’s diagnosis. Apply the right setting-specific rules. Check exclusions. Consider the correct sequencing. Lastly, review the service documentation.
Use the checklist when reviewing your next hypokalemia case. When a case record does not resolve a significant question, request a clarification from the physician. Alternatively, you may request a coding review from a colleague before submitting the claim for payment.
