Summary & Overview
CPT 84425: Thiamine (Vitamin B1) Blood Test
CPT code 84425 represents a laboratory assay for thiamine (vitamin B1) measurement in blood. This test is used to detect or monitor thiamine deficiency, guide nutritional management, and support diagnosis of related metabolic or neurologic conditions. As a clinical laboratory service, the code is relevant nationally for hospital and independent laboratories, outpatient collection sites, and clinicians managing patients at risk for deficiency.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical context for thiamine testing, typical sites of service, and the role of CPT code 84425 in billing workflows. The publication outlines common billing practices and modifiers associated with clinical laboratory services, summarizes expected clinical indications for ordering the test, and highlights benchmarking and policy considerations that affect reimbursement and claims processing.
This summary provides actionable reference material for coding professionals, laboratory managers, and clinicians seeking clarity on when and where CPT code 84425 applies and what to expect in payer interactions and administrative processes.
Billing Code Overview
CPT code 84425 describes a laboratory measurement of thiamine (vitamin B1), typically performed on a patient blood specimen. The service involves analysis by a laboratory analyst or technologist to quantify thiamine levels for clinical assessment of nutritional status or suspected deficiency.
-
Service type: Clinical laboratory testing
-
Typical site of service: Hospital laboratory, independent clinical laboratory, or outpatient phlebotomy collection site
Clinical & Coding Specifications
Clinical Context
A typical patient is an adult presenting to an outpatient clinic or emergency department with symptoms of peripheral neuropathy, unexplained anemia, chronic alcohol use, malnutrition, or postoperative malabsorption. The clinician orders a plasma or whole blood thiamine (vitamin B1) level to evaluate for deficiency as part of a metabolic and nutritional workup. A phlebotomy technician draws a blood specimen using standard venipuncture technique; the sample is processed and sent to the clinical laboratory. The clinical laboratory analyst performs CPT 84425 by measuring thiamine in the specimen, often using high-performance liquid chromatography (HPLC) or mass spectrometry. Results are reviewed by the laboratory and reported to the ordering clinician, who integrates the value with clinical findings and other laboratory tests (for example complete blood count, metabolic panel, and vitamin B12 and folate levels) to guide diagnosis and management. Typical sites of service include outpatient ambulatory clinics, hospital inpatient floors, emergency departments, and reference laboratories.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | When billing only the professional interpretation/reporting portion of a test performed by a separate laboratory |