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CPT 78122: Whole Blood Volume Study via Isotope Dilution

CPT code 78122 represents a diagnostic nuclear medicine procedure to determine whole blood volume, including red blood cell and plasma volumes, using an isotope dilution technique with radiolabeled autologous red blood cells. This test is used to quantify circulating blood components for clinical decisions in hematology, transfusion planning, and complex volume-status assessments. Nationally, accurate coding of this procedure matters for consistent clinical reporting, appropriate facility billing, and resource allocation in imaging and nuclear medicine services.

Key payers in the analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context for why the study is ordered, typical sites of service where it is performed, and common modifiers and administrative elements associated with billing. The publication outlines benchmarks and coverage considerations where available, highlights coding nuances for documentation and reporting, and summarizes policy and reimbursement updates affecting nuclear medicine diagnostic studies. The content is designed to inform coding professionals, billing managers, and clinical leaders on national coding practice and operational implications for CPT code 78122.

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Billing Code Overview

CPT code 78122 describes a whole blood volume study using an isotope dilution technique. The procedure measures total blood volume, including red blood cell volume and plasma volume, by injecting a radiopharmaceutical or radiotracer and the patient’s own red blood cells tagged with a tracer, then calculating volumes after adequate mixing.

Service type: Diagnostic nuclear medicine / radiolabeled blood volume study
Typical site of service: Hospital outpatient imaging department, nuclear medicine facility, or specialized diagnostic center

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CPT 78122: Whole Blood Volume Study via Isotope Dilution

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Billing Code Overview

Service type: Diagnostic nuclear medicine / radiolabeled blood volume study
Typical site of service: Hospital outpatient imaging department, nuclear medicine facility, or specialized diagnostic center

Clinical & Coding Specifications

Clinical Context

A 58-year-old patient with congestive heart failure and unexplained anemia is referred for measurement of whole blood volume to differentiate true anemia from plasma volume expansion. The nuclear medicine team schedules a quantitative blood volume study using isotope dilution. The procedure involves withdrawing a baseline blood sample, labeling the patient’s red blood cells with a radiotracer (commonly technetium-99m), reinjecting the tagged cells and a known quantity of radiopharmaceutical, then obtaining timed blood samples and counting radioactivity to calculate red blood cell and plasma volumes. The workflow includes pre-procedure consent and allergy review, venous access placement, baseline vital signs, specimen labeling, radiopharmacy preparation of tracer, in-procedure blood draws at specified intervals, laboratory/radiation counts, calculation of total blood, red cell and plasma volumes, documentation of results and interpretation by a nuclear medicine physician, and communication of results to the referring hematologist or cardiologist. Typical site of service is an outpatient nuclear medicine or hospital-based imaging department with capability for radiopharmaceutical handling and inpatient bed availability when clinically indicated.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the physician interpretation/reporting portion separate from technical services.
`TC`	Technical component	Use when billing only the technical portion (radiopharmacy, isotope administration, equipment, technologist time).
`59`	Distinct procedural service	Data not available in the input.
`76`	Repeat procedure by same physician	Data not available in the input.
`77`	Repeat procedure by another physician	Data not available in the input.
`52`	Reduced services	Use when the study is partially completed or limited and full protocol is not performed.
`53`	Discontinued procedure	Use when the test is started but terminated due to patient intolerance or adverse reaction.
`78`	Unplanned return to operating/procedure room	Use if patient requires an immediate unplanned return for a related procedure or complication.
`80`	Assistant surgeon	Data not available in the input.
`22`	Increased procedural services	Use when the study requires substantially greater resources or time than usual (document rationale).
`23`	Unusual anesthesia	Use if anesthesia beyond local or minimal sedation is medically necessary for the study.
`50`	Bilateral procedure	Not typically applicable but may be used in systems requiring laterality reporting for paired procedures.
`62`	Two surgeons	Data not available in the input.
`66`	Surgical team physician	Data not available in the input.

Taxonomy Code	Specialty	Notes
207RC0000X	Radiology — Diagnostic Radiology	Nuclear medicine blood volume studies are often ordered and interpreted by diagnostic radiologists or nuclear medicine physicians.
2080P0001X	Nuclear Medicine	Nuclear medicine physicians directly oversee radiopharmaceutical preparation, injection and interpretation.
207L00000X	Pathology — Clinical Pathology	Clinical pathologists or hematologists may be involved in interpreting blood volume results in context of anemia evaluation.
2084N0400X	Hematology	Hematologists frequently order and act on blood volume study results when evaluating anemia and volume status.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
Data not available in the input.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`78200`	Preparation and administration of radiopharmaceutical; diagnostic, single study	Often performed prior to or as part of nuclear medicine workflows when preparing/administering tracers used in blood volume studies.
`78280`	Multiple point blood sampling, radioassay; blood volume study	Directly related technique code representing sampling and radioassay steps used to calculate volumes (often billed in conjunction when applicable).
`36591`	Collection of blood from indwelling catheter, any method	Used when blood samples for the isotope dilution are drawn from an existing central venous catheter instead of peripheral sticks.
`36510`	Insertion of non-tunneled centrally inserted central venous catheter, age 5 years or older	May be performed if central access is required for multiple timed blood draws in inpatients.
`93000`	Electrocardiogram, routine ECG with interpretation and report	Pre-procedure monitoring or baseline assessment in patients with cardiac disease undergoing the study may include ECG documentation.

CPT 78102: Limited-Area Bone Imaging After Radiotracer Administration

CPT-78103-NUCLEAR-MEDICINE-BONE-SCAN

CPT 78103: Nuclear Medicine Bone Scan, Whole Body/Multi-Phase

CPT-78104-WHOLE-BODY-BONE-SCAN

CPT 78104: Whole-Body Bone Scan, Skeletal Scintigraphy

CPT-78110-SINGLE-SAMPLE-PLASMA-VOLUME-DETERMINATION

CPT 78110: Single-Sample Plasma Volume Determination

CPT-78111-PLASMA-VOLUME-MULTIPLE-SAMPLE-METHOD

CPT 78111: Plasma Volume Measurement, Multiple Sample Method

CPT-78120-RADIOLABELED-SINGLE-SAMPLE-RED-CELL-VOLUME

CPT 78120: Single-Sample Radiolabeled Red Cell Volume Determination

CPT-78121-RED-CELL-VOLUME-MULTIPLE-SAMPLE-METHOD

CPT 78121: Red Cell Volume Measurement, Multiple Sample Method

CPT-78130-RED-BLOOD-CELL-SURVIVAL-STUDY-AUTOLOGOUS-RADIOLABEL

CPT 78130: Red Blood Cell Survival Study, Autologous Radiolabel

CPT-78140-LIVER-SPLEEN-RADIOLABELED-RED-BLOOD-CELL-SCAN

CPT 78140: Liver and Spleen Scan with Radiolabeled Autologous Red Blood Cells

CPT-78185-SPLEEN-RADIONUCLIDE-SCAN-SPLENIC-IMAGING

CPT 78185: Radionuclide Spleen Study

Showing 1–10 of 13

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the physician interpretation/reporting portion separate from technical services.
`TC`	Technical component	Use when billing only the technical portion (radiopharmacy, isotope administration, equipment, technologist time).
`59`	Distinct procedural service	Data not available in the input.
`76`	Repeat procedure by same physician	Data not available in the input.
`77`	Repeat procedure by another physician	Data not available in the input.
`52`	Reduced services	Use when the study is partially completed or limited and full protocol is not performed.
`53`	Discontinued procedure	Use when the test is started but terminated due to patient intolerance or adverse reaction.
`78`	Unplanned return to operating/procedure room	Use if patient requires an immediate unplanned return for a related procedure or complication.
`80`	Assistant surgeon	Data not available in the input.
`22`	Increased procedural services	Use when the study requires substantially greater resources or time than usual (document rationale).
`23`	Unusual anesthesia	Use if anesthesia beyond local or minimal sedation is medically necessary for the study.
`50`	Bilateral procedure	Not typically applicable but may be used in systems requiring laterality reporting for paired procedures.
`62`	Two surgeons	Data not available in the input.
`66`	Surgical team physician	Data not available in the input.

Taxonomy Code	Specialty	Notes
207RC0000X	Radiology — Diagnostic Radiology	Nuclear medicine blood volume studies are often ordered and interpreted by diagnostic radiologists or nuclear medicine physicians.
2080P0001X	Nuclear Medicine	Nuclear medicine physicians directly oversee radiopharmaceutical preparation, injection and interpretation.
207L00000X	Pathology — Clinical Pathology	Clinical pathologists or hematologists may be involved in interpreting blood volume results in context of anemia evaluation.
2084N0400X	Hematology	Hematologists frequently order and act on blood volume study results when evaluating anemia and volume status.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
Data not available in the input.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`78200`	Preparation and administration of radiopharmaceutical; diagnostic, single study	Often performed prior to or as part of nuclear medicine workflows when preparing/administering tracers used in blood volume studies.
`78280`	Multiple point blood sampling, radioassay; blood volume study	Directly related technique code representing sampling and radioassay steps used to calculate volumes (often billed in conjunction when applicable).
`36591`	Collection of blood from indwelling catheter, any method	Used when blood samples for the isotope dilution are drawn from an existing central venous catheter instead of peripheral sticks.
`36510`	Insertion of non-tunneled centrally inserted central venous catheter, age 5 years or older	May be performed if central access is required for multiple timed blood draws in inpatients.
`93000`	Electrocardiogram, routine ECG with interpretation and report	Pre-procedure monitoring or baseline assessment in patients with cardiac disease undergoing the study may include ECG documentation.

CPT 78102: Limited-Area Bone Imaging After Radiotracer Administration

CPT-78103-NUCLEAR-MEDICINE-BONE-SCAN

CPT 78103: Nuclear Medicine Bone Scan, Whole Body/Multi-Phase

CPT-78104-WHOLE-BODY-BONE-SCAN

CPT 78104: Whole-Body Bone Scan, Skeletal Scintigraphy

CPT-78110-SINGLE-SAMPLE-PLASMA-VOLUME-DETERMINATION

CPT 78110: Single-Sample Plasma Volume Determination

CPT-78111-PLASMA-VOLUME-MULTIPLE-SAMPLE-METHOD

CPT 78111: Plasma Volume Measurement, Multiple Sample Method

CPT-78120-RADIOLABELED-SINGLE-SAMPLE-RED-CELL-VOLUME

CPT 78120: Single-Sample Radiolabeled Red Cell Volume Determination

CPT-78121-RED-CELL-VOLUME-MULTIPLE-SAMPLE-METHOD

CPT 78121: Red Cell Volume Measurement, Multiple Sample Method

CPT-78130-RED-BLOOD-CELL-SURVIVAL-STUDY-AUTOLOGOUS-RADIOLABEL

CPT 78130: Red Blood Cell Survival Study, Autologous Radiolabel

CPT-78140-LIVER-SPLEEN-RADIOLABELED-RED-BLOOD-CELL-SCAN

CPT 78140: Liver and Spleen Scan with Radiolabeled Autologous Red Blood Cells

CPT-78185-SPLEEN-RADIONUCLIDE-SCAN-SPLENIC-IMAGING

CPT 78185: Radionuclide Spleen Study

Showing 1–10 of 13

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

OpenPayer

CPT 78122: Whole Blood Volume Study via Isotope Dilution

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Billing Code Overview

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CPT 78122: Whole Blood Volume Study via Isotope Dilution

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

CPT 78122: Whole Blood Volume Study via Isotope Dilution

Sign up for cpt 78122 policy alerts

Billing Code Overview

CPT 78122: Whole Blood Volume Study via Isotope Dilution

Sign up for cpt 78122 policy alerts

Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

What does CPT 78122 describe and where is it typically performed?

Which billing modifiers are relevant for CPT 78122?

Are there related CPT codes that are commonly billed with 78122?

What is the typical clinical workflow and who orders or interprets the study?

Which payers are included in the analysis and are coverage details provided?

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

What does CPT 78122 describe and where is it typically performed?

Which billing modifiers are relevant for CPT 78122?

Are there related CPT codes that are commonly billed with 78122?

What is the typical clinical workflow and who orders or interprets the study?

Which payers are included in the analysis and are coverage details provided?

References