What Is Hypernatremia
Hypernatremia occurs when the blood sodium concentration rises above the normal range, usually higher than 145 mmol/L. Sodium plays a vital role in nerve signaling, muscle contractions, and water balance in the body. When sodium levels climb, water shifts out of cells, making them shrink. Brain cells are particularly sensitive, which explains why neurological symptoms often appear first.
Causes of Hypernatremia
Hypernatremia is almost always caused by a loss of water, a gain of sodium, or a combination of both. Common causes include:
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Dehydration: The most frequent cause, especially in elderly or debilitated patients with limited access to water.
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Renal problems: Kidney diseases that impair the ability to concentrate urine can lead to water loss.
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Medications: Diuretics, certain antibiotics, and lithium can trigger elevated sodium levels.
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Gastrointestinal losses: Prolonged diarrhea or vomiting may cause more water than sodium loss.
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Endocrine disorders: Diabetes insipidus leads to excessive water loss, resulting in hypernatremia.
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Iatrogenic causes: Excessive administration of sodium bicarbonate, hypertonic saline, or tube feeding formulas.
These causes should be documented in the medical record to support accurate use of the ICD-10 code.
The ICD-10 Code for Hypernatremia
The official ICD-10-CM code for hypernatremia is E87.0, which also includes hyperosmolality. It is listed under “Other disorders of fluid, electrolyte and acid-base balance.”
When to Use E87.0
The code should be used when:
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Sodium levels are above normal and clinically significant.
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Symptoms like confusion, lethargy, or seizures are documented.
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There is a clear cause or associated condition that explains the imbalance.
Severity Levels
While ICD-10 does not provide separate codes for mild versus severe hypernatremia, documentation should clearly state the severity. For example, “mild asymptomatic hypernatremia” versus “severe hypernatremia with encephalopathy.” This improves coding accuracy and supports medical necessity.
Coding Guidelines and Documentation
Accurate use of E87.0 requires adherence to coding guidelines for hypernatremia:
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Lab Evidence: Always include sodium levels, typically >145 mmol/L.
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Symptom Description: Confusion, muscle twitching, seizures, or coma should be noted if present.
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Cause and Context: Link hypernatremia to underlying issues such as dehydration, renal failure, or medication.
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Exclusion Notes: Do not code hypernatremia separately if it is already captured by another diagnosis, like hyperosmolar hyperglycemic state in diabetes.
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Population Specificity: Use neonatal codes (e.g., P74.21 for newborn hypernatremia) rather than E87.0 for infants.
This ensures the electrolyte imbalance code is applied correctly.
Clinical Importance and Treatment Snapshot
Hypernatremia can be life-threatening if not recognized early. Severe cases are associated with high mortality in hospitalized patients. Even mild sodium excess may worsen outcomes in elderly or critically ill individuals.
Treatment usually includes:
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Restoring fluids with IV hypotonic solutions or oral water.
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Correcting sodium slowly to avoid cerebral edema.
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Addressing the underlying cause, whether renal, endocrine, or iatrogenic.
While treatment details are not coded, understanding them helps coders interpret documentation.
Comparing Hypernatremia with Related Conditions
| Condition | ICD-10 Code | Key Difference |
|---|---|---|
| Hypernatremia | E87.0 | High sodium, often dehydration or sodium gain. |
| Hyponatremia | E87.1 | Low sodium, opposite imbalance. |
| Hyperosmolality | E87.0 | Same code as hypernatremia since both overlap. |
| Neonatal Hypernatremia | P74.21 | Newborn-specific code. |
This comparison helps avoid coding errors, especially when hypernatremia occurs alongside other electrolyte disorders.
Example Scenarios
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ICU Patient with Multiple Imbalances: A 70-year-old man with renal failure, sodium 160 mmol/L, hyperkalemia, and confusion. Hypernatremia is documented as acute and symptomatic. Code: E87.0 plus codes for additional electrolyte issues.
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Outpatient Case: A 55-year-old woman with mild hypernatremia (148 mmol/L) during a routine checkup, asymptomatic, attributed to diuretics. Code: E87.0, with documentation clarifying mild severity.
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Dialysis Patient: A patient on hemodialysis with recurrent hypernatremia after sessions. Documented as chronic and monitored closely. Code: E87.0 with underlying renal disease codes.
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Neonate with Feeding Issues: Newborn with hypernatremia due to inadequate breastfeeding. Correct code: P74.21, not E87.0.
These examples show how context determines proper coding.
FAQs
What is the ICD-10 code for hypernatremia?
The ICD-10-CM code is E87.0, which also covers hyperosmolality.
Does ICD-10 distinguish between mild and severe hypernatremia?
No. E87.0 is used for both. Documentation should describe severity.
What if the patient has both hypernatremia and another electrolyte disorder?
Each condition should be coded separately if it is clinically relevant and documented.
Can E87.0 be used in newborns?
No. Neonatal cases use P74.21.
What is needed in documentation for coding hypernatremia?
Sodium level, symptoms, timing, and underlying cause. This ensures compliance with coding guidelines.
Conclusion
Hypernatremia is a significant electrolyte disorder that demands accurate recognition and coding. The correct ICD-10 code for hypernatremia is E87.0, which also applies to hyperosmolality. Coders should ensure documentation captures sodium levels, symptoms, causes, and severity.
By following coding guidelines for hypernatremia, healthcare teams protect patient safety, support proper billing, and maintain reliable medical data. In short, accurate coding of sodium excess is more than a technical task—it safeguards both care quality and healthcare integrity.