CPT code 84588 identifies a quantitative laboratory assay for vasopressin (antidiuretic hormone, ADH). The test is clinically important for diagnosing and managing disorders of water and sodium homeostasis, such as diabetes insipidus and SIADH, and has national relevance because it supports inpatient and outpatient diagnostic pathways in hospitals and reference laboratories. Payers evaluated in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.

Readers will find a concise overview of the procedure and its clinical context, common sites of service, and how the test fits into diagnostic workflows. The publication also covers payer coverage patterns and benchmark information where available, identifies coding and billing considerations tied to laboratory services, and summarizes relevant policy updates that affect payment and utilization. Clinical implications for patient care and typical use cases are described to inform payers, hospital billing staff, and laboratory managers. Data not available in the input is noted where applicable.