ICD-10 Code for Testing Hyponatremia Potentially Caused by Escitalopram
Use ICD-10 code E87.1 (Hypo-osmolality and hyponatremia) as the primary diagnosis code for ordering laboratory tests to evaluate hyponatremia potentially caused by escitalopram.
Primary Diagnostic Code
- E87.1 is the appropriate ICD-10 code for hyponatremia and should be used when ordering serum sodium, serum osmolality, urine osmolality, and urine sodium tests 1, 2.
Additional Relevant Codes to Consider
When documenting the clinical context, you may also need to include:
- F32.x or F33.x (Depressive disorder codes) - to document the underlying condition being treated with escitalopram 1, 2
- T43.225A (Adverse effect of selective serotonin reuptake inhibitors, initial encounter) - if hyponatremia is confirmed to be drug-induced 1, 2
- E22.2 (Syndrome of inappropriate secretion of antidiuretic hormone/SIADH) - if SIADH is confirmed as the mechanism 1, 2, 3
Clinical Context for Testing
Escitalopram-induced hyponatremia typically presents within the first 2 weeks to 2 months of therapy and is most common in elderly patients, particularly women 1, 2, 4, 5. The mechanism is SIADH (syndrome of inappropriate antidiuretic hormone secretion) 1, 2, 3.
Key Laboratory Tests to Order with E87.1:
- Serum sodium (to confirm hyponatremia, typically <134 mEq/L) 6, 1, 2
- Serum osmolality (expect <275 mosm/kg in SIADH) 6
- Urine osmolality (inappropriately high, >300-500 mosm/kg) 6
- Urine sodium concentration (>20-40 mEq/L) 6
- Serum creatinine and BUN (to exclude renal dysfunction) 6
- Thyroid function tests (to exclude hypothyroidism) 6
- Cortisol level (to exclude adrenal insufficiency) 6
High-Risk Patient Characteristics:
- Elderly patients (especially >60 years old) 1, 2, 3, 5
- Female gender 1, 2, 5
- Lower body weight 3
- First 2 weeks to 2 months of SSRI therapy 1, 2, 4
- Patients with dementia 4
- Diabetic patients 3
Important Clinical Caveat
Severe symptomatic hyponatremia (sodium <120-125 mEq/L) can present with seizures, confusion, delirium, and altered mental status 1, 2, 3, 4. If hyponatremia is confirmed and attributed to escitalopram, discontinuation of the medication is essential, and rechallenge is strongly discouraged 4, 5. Recurrent hyponatremia has been documented with escitalopram rechallenge 4.