Summary & Overview
CPT 78120: Single-Sample Radiolabeled Red Cell Volume Determination
Headline: CPT code 78120 covers a single-sample radiolabeled red cell volume determination, a nuclear medicine technique to quantify a patient’s red cell volume. Lead: CPT code 78120 represents a diagnostic procedure in which a measured quantity of radiolabeled red blood cells is administered and a single post-mixing blood sample is analyzed to calculate red cell volume — a targeted test used in select hematology and volume assessment contexts. National significance: The procedure is clinically relevant for evaluating blood volume disorders, anemia characterization, and pre-procedural hematologic assessment, and it has implications for resource use in outpatient nuclear medicine and hospital laboratories. Key payers covered: Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. What readers will learn: This publication explains what CPT code 78120 represents, its clinical purpose, typical sites of service, and the payer landscape addressed in the analysis. It provides benchmarks and coding context where available, highlights common billing modifiers and operational considerations, and summarizes implications for billing workflows. It also identifies where input data are missing. Scope: Content is national in focus and intended to inform coding, billing, and clinical stakeholders about the definition and practical context of CPT code 78120.
Billing Code Overview
CPT code 78120 describes a single-sample radiolabeled red cell volume determination. In this procedure, a known quantity of red blood cells labeled with a radioactive tracer is introduced into the patient, and after adequate mixing a single blood sample is collected to measure tracer concentration and calculate red cell volume. The service type is diagnostic nuclear medicine / laboratory measurement of blood volume. The typical site of service is an outpatient nuclear medicine or hospital outpatient setting, or a specialized diagnostic laboratory capable of handling radiolabeled blood products. Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A typical patient is an adult referred to a nuclear medicine or hematology service to quantify circulating red cell mass when there is concern for unexplained anemia, polycythemia, hemolysis, or evaluation of blood volume disorders. The patient arrives to an outpatient nuclear medicine suite or hospital radiology/hematology lab. After informed consent, baseline vital signs and intravenous access are obtained. A measured aliquot of the patient’s autologous red blood cells is labeled ex vivo or in vivo with a radioactive tracer (commonly technetium-99m) and a known activity is injected back to the patient. After adequate mixing time, a single blood sample is drawn at the specified interval to measure radioactivity and calculate red cell volume using the single-sample technique represented by 78120. Results are reviewed by the ordering physician (hematologist or nuclear medicine physician) to guide diagnosis and management, such as distinguishing true polycythemia from relative erythrocytosis, assessing blood loss, or evaluating marrow production in anemia.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing solely for physician interpretation when the facility bills technical component. |