Crystal's Coder Hub🧬 [ICD-10 CM] E87.6 — Hypokalemia
Billable Code Confirmed
ICD-10 CM E87.6 is a valid, billable 5-character ICD-10-CM diagnosis code for FY2026. Characters 1-3 (E87) define the category “Other disorders of fluid, electrolyte and acid-base balance”; character 4 (.6) specifies hypokalemia as the distinct subcategory. No additional characters are required for complete specificity.
Non-Billable Parent Codes — Never Submit These
❌
E87— 3-character header — lacks specificity for the type of electrolyte disorder ❌E70-E88— Block header — metabolic disorders category, not reportable Always submit E87.6 (all 5 characters) when hypokalemia is documented with serum potassium <3.5 mEq/L and clinical correlation.
Clinical Context: Acute vs. Chronic Electrolyte Disturbance
ICD-10-CM E87.6 captures laboratory-confirmed low serum potassium regardless of acuity. Unlike congenital potassium metabolism disorders (E83.4-), this code is used for acquired hypokalemia from GI losses, renal wasting, medications (e.g., diuretics), or inadequate intake. Documentation of severity (mild/moderate/severe) and etiology supports accurate coding and DRG assignment.
Code Classification
ICD-10 CM E87.6 — wRVU, assistant payable, and global period fields are not applicable to diagnosis codes. Refer to CPT Procedural Crosswalk and ICD-10-PCS Crosswalk sections for associated procedure coding.
🔍 Code Description
ICD-10 CM E87.6 classifies lower than normal levels of potassium in the circulating blood (serum K+ <3.5 mEq/L). This code exists to distinguish acquired potassium deficiency from congenital disorders of potassium metabolism and from hyperkalemia (E87.5).
Hypokalemia may result from renal potassium wasting (e.g., diuretic use, hyperaldosteronism), gastrointestinal losses (vomiting, diarrhea), transcellular shifts (insulin administration, alkalosis), or inadequate dietary intake. Clinical manifestations range from asymptomatic laboratory finding to muscle weakness, fatigue, cardiac arrhythmias, and paralysis. Key clinical terms include hypopotassemia, potassium depletion, and low serum potassium.
🌳 Code Tree / Hierarchy
E70-E88 [Metabolic disorders] ❌ Non-billable
│
├── E87 [Other disorders of fluid, electrolyte and acid-base balance] ❌ Non-billable
│ │
│ ├── E87.0 [Hyperosmolality and hypernatremia] ✅ Billable
│ ├── E87.1 [Hypo-osmolality and hyponatremia] ✅ Billable
│ ├── E87.2 [Acidosis] ❌ Non-billable
│ │ ├── E87.20 [Acidosis, unspecified] ✅ Billable
│ │ ├── E87.21 [Acute metabolic acidosis] ✅ Billable
│ │ └── E87.22 [Chronic metabolic acidosis] ✅ Billable
│ ├── E87.3 [Alkalosis] ✅ Billable
│ ├── E87.4 [Mixed disorder of acid-base balance] ✅ Billable
│ ├── E87.5 [Hyperkalemia] ✅ Billable
│ ├── E87.6 [Hypokalemia] ◀ THIS CODE ✅ Billable
│ └── E87.7 [Fluid overload] ❌ Non-billable
│ ├── E87.70 [Fluid overload, unspecified] ✅ Billable
│ └── E87.71 [Transfusion associated circulatory overload] ✅ Billable
│
└── E88 [Other and unspecified metabolic disorders] ❌ Non-billable
Severity Documentation Impacts DRG Assignment
While E87.6 itself is not a CC/MCC, documenting severity (e.g., “severe hypokalemia, K+ 2.2 mEq/L”) with associated complications (arrhythmia, rhabdomyolysis) supports pairing with true MCC codes, which can shift DRG assignment from 641 to the higher-weighted 640, impacting reimbursement.
✅ Includes
The following clinical terms and scenarios map to E87.6 when documented:
- Serum potassium <3.5 mEq/L with clinical correlation
- Potassium deficiency due to diuretic therapy
- Hypokalemia secondary to vomiting or diarrhea
- Hypokalemic periodic paralysis (acquired form)
- Drug-induced hypokalemia (e.g., loop/thiazide diuretics, amphotericin B)
❌ Excludes
Excludes 1 — Cannot Be Coded Simultaneously with E87.6
| Code | Description | Note |
|---|---|---|
| E23.2 | Diabetes insipidus | Mutually exclusive endocrine disorder; code underlying cause of electrolyte disturbance instead |
| O21.1 | Electrolyte imbalance associated with hyperemesis gravidarum | Pregnancy-specific code takes precedence; do not use E87.6 for obstetric electrolyte disorders |
| O08.5 | Electrolyte imbalance following ectopic or molar pregnancy | Obstetric complication code is primary; E87.6 is excluded |
| G72.3 | Familial periodic paralysis | Congenital neuromuscular disorder; use congenital potassium metabolism codes (E83.4-) if applicable |
| P19.9 | Metabolic acidemia in newborn, unspecified | Neonatal metabolic disorder; use newborn-specific codes |
Excludes 1 Violation Risk
A common error is reporting E87.6 alongside O21.1 for a pregnant patient with vomiting-induced hypokalemia. Per Excludes1 guidance, the obstetric code (O21.1) must be used alone; E87.6 should not be reported concurrently. Correct action: sequence O21.1 as principal diagnosis when pregnancy-related.
Excludes 2 — May Be Coded in Addition if Separately Present
| Code | Description | Note |
|---|---|---|
| E83.4- | Disorders of potassium metabolism (congenital) | If patient has both congenital potassium metabolism disorder AND acquired hypokalemia exacerbation, both may be reported with E83.4- sequenced first |
📋 Clinical Overview
Etiology-Based Distinction for Accurate Code Selection
The table below compares E87.6 with related electrolyte codes to clarify when hypokalemia should be coded versus other fluid/electrolyte disorders.
| Feature | E87.6 — Hypokalemia | E87.5 — Hyperkalemia | E87.1 — Hyponatremia |
|---|---|---|---|
| Serum Threshold | K+ <3.5 mEq/L | K+ >5.0 mEq/L | Na+ <135 mEq/L |
| Common Causes | Diuretics, GI losses, renal wasting | Renal failure, ACE inhibitors, tissue breakdown | SIADH, heart failure, diuretics |
| Cardiac Manifestations | T-wave flattening, U waves, arrhythmias | Peaked T waves, widened QRS, arrhythmias | Usually neurologic (confusion, seizures) |
| Acute Management | Oral/IV potassium replacement | Calcium gluconate, insulin/glucose, dialysis | Fluid restriction, hypertonic saline |
| Coding Specificity | Document severity & etiology | Document severity & etiology | Document acuity & volume status |
CDI Query Trigger — Missing Severity or Etiology
When documentation states only “low potassium” or “hypokalemia” without serum value, clinical context, or etiology, a CDI query should request: “Please clarify serum potassium level, acuity (acute vs. chronic), and suspected etiology (e.g., diuretic-induced, GI losses) to support accurate code selection and DRG assignment.”
Manifestations & Symptom Burden
Relevant manifestations and clinical indicators for E87.6:
- Muscle weakness/fatigue: Generalized or proximal weakness due to impaired neuromuscular conduction
- Cardiac arrhythmias: Palpitations, ECG changes (flattened T waves, prominent U waves, ST depression)
- Gastrointestinal: Ileus, constipation, nausea due to smooth muscle hypomotility
- Renal: Polyuria, polydipsia from impaired concentrating ability
Coding Manifestations
Always code documented manifestations to fully capture clinical complexity. Examples include: I49.9 — Cardiac arrhythmia, unspecified (when ECG abnormalities documented) M62.82 — Rhabdomyolysis (if severe hypokalemia causes muscle breakdown) K59.00 — Constipation, unspecified (if ileus or hypomotility documented)
💰 HCC Risk Adjustment (CMS-HCC v28)
| Field | Detail |
|---|---|
| CMS-HCC Model Version | v28 (2024-2026 Implementation) |
| HCC Assignment | ❌ Not Mapped — N/A |
| HCC Category | N/A — Electrolyte disorders not included in v28 |
| RAF Coefficient | 0.000 — No contribution to risk score |
E87.6 does not map to an HCC under CMS-HCC Model v28. Electrolyte disturbances are generally acute or treatment-responsive conditions not predictive of long-term resource utilization in the Medicare Advantage population.
Focus on Chronic Comorbidities for RAF Capture
🏥 MS-DRG Assignment
MDC 10 — Endocrine, Nutritional & Metabolic Diseases & Disorders
| DRG | Title | Est. Relative Weight* |
|---|---|---|
| DRG 640 | Miscellaneous disorders of nutrition, metabolism, fluids and electrolytes with MCC | ~1.3356 |
| DRG 641 | Miscellaneous disorders of nutrition, metabolism, fluids and electrolytes without CC/MCC | ~0.7782 |
*Approximate. Verify against IPPS FY2026 Final Rule tables.
Sequencing and Complications
E87.6 is rarely appropriate as a principal diagnosis unless hypokalemia is the sole reason for admission (e.g., severe symptomatic hypokalemia requiring IV replacement). More commonly, it sequences as a secondary diagnosis. When paired with a true MCC (e.g., N17.9 acute kidney injury, J69.0 acute respiratory failure), the case may group to DRG 640 instead of 641. Document severity and associated complications to support accurate DRG assignment.
🔗 Related ICD-10-CM Codes
Electrolyte Disorder Variants
| Code | Description |
|---|---|
| E87.6 | Hypokalemia ← This Code |
| E87.5 | Hyperkalemia |
| E87.1 | Hypo-osmolality and hyponatremia |
| E87.0 | Hyperosmolality and hypernatremia |
Etiology-Specific Potassium Disorders
| Code | Description |
|---|---|
| E83.40 | Disorder of potassium metabolism, unspecified |
| E83.49 | Other disorders of potassium metabolism |
| P74.32 | Hypokalemia of newborn |
🛠️ Commonly Associated CPT Codes (Internal Medicine / Hospital Setting)
Outpatient and Inpatient Profee Setting Context
These CPT codes are typically reported for evaluation, monitoring, or treatment of hypokalemia in office, ED, or inpatient settings. Ensure documentation supports medical necessity for each service.
| CPT Code | Description | Profee Coding Notes (Modifier 26) |
|---|---|---|
| 84132 | Potassium, serum, plasma, or whole blood | Most specific test; do not bill with panels 80048/80051/80053 per NCCI |
| 80048 | Basic metabolic panel (BMP) | Includes potassium; report instead of 84132 when full panel ordered |
| 80051 | Electrolyte panel | Includes potassium, sodium, chloride, CO2; unbundling risk if 84132 added |
| 93000 | Electrocardiogram, routine ECG with interpretation | Report when cardiac symptoms or arrhythmia documented; supports medical necessity |
| 99213-99215 | Office/outpatient E/M, established patient | Level based on MDM; hypokalemia management often supports moderate complexity |
| 99221-99223 | Initial hospital care | Use for inpatient admission with hypokalemia as principal or significant secondary |
NCCI Bundling Considerations CPT 84132 billed on the same day as 80048, 80051, or 80053 is bundled per NCCI edits; potassium testing is a component of these panels. Modifier -59 is not appropriate to unbundle in this context. For E/M services, ensure documentation reflects evaluation/management beyond routine lab review to support separate reporting.
🔬 ICD-10-PCS Crosswalk (Inpatient Procedures)
When E87.6 is an inpatient diagnosis, these PCS codes are relevant for associated inpatient procedures.
| PCS Section | Body System | Root Operation | Clinical Application |
|---|---|---|---|
| 3 (Administration) | 3 (Circulatory System) | 0 (Introduction) | IV potassium chloride infusion for severe hypokalemia; example: 3E033GC (Introduction of electrolyte, potassium, into peripheral vein, percutaneous approach) |
| 3 (Administration) | 3 (Circulatory System) | 0 (Introduction) | Oral potassium replacement via NG tube; example: 3E0G36Z (Introduction of other therapeutic substance into upper GI, via natural or artificial opening) |
💊 Coding Scenarios and Examples
Scenario 1 — [Outpatient Office Visit]: Mild Hypokalemia, Diuretic-Induced
Clinical Vignette: A 68-year-old female with hypertension presents for routine follow-up. She reports mild fatigue and muscle cramps. Labs show serum potassium 3.2 mEq/L. Provider documents “mild hypokalemia likely related to hydrochlorothiazide therapy” and prescribes oral potassium chloride 20 mEq daily with repeat labs in 2 weeks.
E87.6 — Hypokalemia (principal diagnosis; confirmed by lab value and clinical correlation)
Z79.899* — Other long term (current) drug therapy (to capture chronic diuretic use)
99214 — Office visit, established patient, moderate complexity (supports MDM with new problem requiring prescription and monitoring)
80048* — Basic metabolic panel (includes potassium; do not separately bill 84132)
Scenario 2 — [Inpatient Admission]: Severe Hypokalemia with Cardiac Arrhythmia Clinical Vignette: A 72-year-old male is admitted with palpitations and weakness. ECG shows flattened T waves and prominent U waves. Serum potassium is 2.4 mEq/L. Provider documents “severe hypokalemia with associated cardiac arrhythmia” and initiates IV potassium replacement with telemetry monitoring.
Principal Diagnosis:
E87.6 — Hypokalemia (reason for admission; severe, symptomatic)
Secondary Diagnoses:
I49.9 — Cardiac arrhythmia, unspecified (MCC that supports DRG 640 assignment)
I10 — Essential (primary) hypertension (chronic comorbidity)
MS-DRG Assignment: Case groups to DRG 640 (with MCC) due to presence of I49.9 as a secondary diagnosis with cardiac manifestations, resulting in higher relative weight (~1.3356) versus DRG 641 without MCC.
Scenario 3 — CDI Query: Vague Documentation of “Low Potassium” Clinical Vignette: Discharge summary states “patient had low potassium during hospitalization” without serum value, clinical correlation, or treatment documented. Potassium replacement was administered per nursing notes, but provider assessment lacks specificity.
Action / Outcome:
Coding uncertainty: Cannot determine if hypokalemia was acute, chronic, mild, or severe; unclear if clinically significant or incidental lab finding.
CDI Query Sent: “Please clarify: (1) Was the low potassium clinically significant (e.g., associated with symptoms, ECG changes, or requiring treatment)? (2) What was the documented serum potassium value? (3) Was the hypokalemia acute or chronic? (4) What was the suspected etiology (e.g., diuretic, GI losses)?”
Query Response: Provider updates documentation to confirm: “Patient developed acute, symptomatic hypokalemia with serum K+ 2.8 mEq/L, associated with muscle weakness and ECG U waves, likely due to IV furosemide therapy; treated with IV potassium chloride.”
Corrected ICD-10-CM Coding:
E87.6 — Hypokalemia (now supported by severity, symptoms, and treatment)
T36.5X5A — Adverse effect of diuretics, initial encounter (if furosemide causality confirmed)
⚠️ Coding Pitfalls and Tips
| Pitfall or Tip | |
|---|---|
| ❌ | Coding hypokalemia without lab confirmation. E87.6 requires documented serum potassium <3.5 mEq/L. Do not code based on clinical suspicion alone without laboratory correlation. |
| ❌ | Reporting E87.6 with obstetric electrolyte codes. Per Excludes1, do not report E87.6 with O21.1 or O08.5. For pregnancy-related electrolyte disorders, use the obstetric code alone. |
| ✅ | Document severity and etiology. Specify mild/moderate/severe and suspected cause (diuretic, GI loss, renal wasting) to support accurate coding, DRG assignment, and clinical communication. |
| ✅ | Avoid NCCI unbundling errors. When billing metabolic panels (80048, 80051, 80053), do not separately report 84132. Potassium testing is bundled per CMS NCCI edits. |
| ✅ | Sequence principal diagnosis appropriately. Use E87.6 as principal only when hypokalemia is the primary reason for admission. Otherwise, sequence the underlying condition first and report E87.6 as secondary. |
📚 Sources
1Centers for Medicare & Medicaid Services & National Center for Health Statistics. ICD-10-CM Official Guidelines for Coding and Reporting, FY2026. 2American Hospital Association. Coding Clinic for ICD-10-CM/PCS, 2Q 2019. 3CMS. Medicare Advantage Risk Adjustment: CMS-HCC Model v28 ICD-10-CM Mappings, 2024-2026. 4CMS. Inpatient Prospective Payment System Final Rule FY2026, MS-DRG Definitions Manual v43.0. 5American Medical Association. CPT Professional Edition 2026. 6UpToDate. Hypokalemia in adults: Clinical manifestations and evaluation. Accessed April 2026.