CPT code 78111 represents a diagnostic laboratory/nuclear medicine procedure for measuring plasma volume by administering a radioactive tracer and obtaining multiple post-mixing samples to calculate tracer dilution. This measurement is used in clinical settings to assess intravascular volume status, support evaluations for anemia, fluid management, and select hematologic or renal assessments. Nationally, accurate coding for specialized diagnostic procedures such as 78111 influences appropriate coverage decisions and claims adjudication across commercial and public payers.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an explanation of the clinical context for plasma volume measurement, typical sites of service, and the service type. The publication provides benchmark-oriented coverage discussion and coding considerations relevant to payers listed above, plus summaries of typical billing modifiers and administrative issues. It also outlines common clinical indications for ordering the test and operational notes on how the multiple sample method differs from single-sample alternatives.

This summary is written for a national audience and aims to clarify what CPT code 78111 denotes, why it matters for clinical and payer workflows, and what readers should expect when reviewing coverage and billing practices for specialized plasma volume studies.