Hyponatremia ICD-10-CM codes

Hyponatremia is coded E87.1 (hypo-osmolality and hyponatremia). The code does not distinguish hypovolemic, euvolemic, or hypervolemic hyponatremia, and it has no severity characters. Hypernatremia is the separate code E87.0. The provider must document hyponatremia; a sodium result on the chemistry panel is not sufficient by itself.

When the syndrome of inappropriate antidiuretic hormone secretion is documented as the cause, assign E22.2 for the SIADH together with E87.1, with E22.2 sequenced first when it is the condition being evaluated. Hypovolemic hyponatremia from volume loss is coded with E86.0 for the dehydration, and hypervolemic hyponatremia in heart failure or cirrhosis is coded with the underlying condition and E87.70 (fluid overload, unspecified) if the provider documents fluid overload.

Drug-induced hyponatremia, most often from thiazide diuretics, is E87.1 followed by T50.2X5A (adverse effect of benzothiadiazides and other diuretics); for SSRIs or other agents use the matching T36 to T50 adverse effect code with a fifth or sixth character of 5. Symptoms such as confusion or seizures attributed to the hyponatremia are coded in addition when they are documented and treated. Hyponatremia is a frequent principal diagnosis for admissions from the emergency department when it is the reason for admission and the focus of treatment.