ICD-10 Code E87.1 – Hypo-osmolality and hyponatremia (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E87.1 – Hypo-osmolality and hyponatremia
What it is
E87.1 identifies a disorder of low serum sodium, often with reduced plasma osmolality. Use it when the record documents hypo-osmolality, hyponatremia, or both together.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include confusion, weakness, nausea, headache, or altered mental status when the low sodium state is clinically significant.
When to use this code
Use this code when the provider documents hyponatremia, hypo-osmolality, or a related electrolyte imbalance as an active diagnosis. It also fits inpatient or outpatient records where the condition is evaluated, monitored, or treated.
Code it only when the condition is clearly stated or supported by the assessment. If the chart mentions abnormal sodium without a diagnosis, check documentation before assigning E87.1.
Do not use for
Do not use this code for hypernatremia or other sodium disorders. If the note only reports a lab abnormality without a diagnosis, check documentation.
Coding tip
Look for the provider’s final assessment, not just lab results, before assigning E87.1.