Summary & Overview
CPT 82379: Total and Free Carnitine Measurement
CPT code 82379 represents measurement of both total and free carnitine in serum, plasma, urine, or tissue. Carnitine testing identifies abnormalities in cellular fatty acid transport and mitochondrial fuel utilization and is commonly used to follow up positive newborn screening results or to evaluate suspected metabolic disorders. Nationally, this lab test supports diagnostic pathways for inherited metabolic conditions and influences clinical management in neonates and patients with muscle weakness or hypoketotic hypoglycemia.
Key payers in the coverage landscape include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of the clinical context for ordering carnitine testing, typical sites where the service is delivered, and the common billing environment for laboratory biochemical analyses. The publication summarizes benchmarks and payer coverage patterns where available, outlines relevant coding considerations for the laboratory service line, and highlights policy updates that affect laboratory authorization and medical necessity evaluation. The material is intended to support billing, coding, and policy teams, as well as clinicians seeking concise context for CPT code 82379.
Billing Code Overview
CPT code 82379 describes laboratory measurement of total and free carnitine in serum, plasma, urine, or tissue specimens. Total carnitine comprises both free carnitine and acylcarnitines, which are carriers that transport long‑chain fatty acids into mitochondria for use as cellular fuel. This testing is clinically relevant for evaluation of suspected carnitine deficiency or disorders of fatty acid oxidation and is often ordered after a newborn screen returns a positive blood spot result.
Service Type: Clinical laboratory biochemical analysis
Typical Site of Service: Clinical laboratory, hospital lab, reference laboratory, or specialty testing facility
Clinical & Coding Specifications
Clinical Context
A newborn infant born at a community hospital has a positive newborn screening blood spot for possible carnitine deficiency. The pediatrician orders quantitative serum testing for both total and free carnitine to confirm the screen. The infant is brought to the hospital outpatient laboratory or the hospital clinical chemistry laboratory where a phlebotomy technician collects a serum or plasma specimen. The specimen is sent to the biochemical genetics or hospital chemistry lab where a laboratory analyst performs analysis for total and free carnitine (CPT 82379). Results are reviewed by the pediatrician or a metabolic specialist; abnormal results prompt confirmatory testing, metabolic consult, nutritional counseling, and potential initiation of carnitine supplementation. Typical workflow steps: order placement in the electronic health record, specimen collection (serum, plasma, or urine), specimen processing and testing in the lab, result verification by laboratory personnel, and clinician review with documentation in the infant’s chart. Typical sites of service include hospital outpatient laboratory, ambulatory clinic laboratory, reference laboratory, and inpatient hospital laboratory when performed on hospitalized infants or patients under metabolic workup.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional Component | Use when billing only the physician or pathologist interpretation component and the laboratory component is billed by another entity. |