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    v1.0.31
    OpenPayerBilling CodesProprietary Laboratory AnalysesCPT cpt-0399u-folate-receptor-antibody-test-frat
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    CPT 0399U: FRAT® Folate Receptor Antibody Test (ELISA)

    CPT code 0399U is a Proprietary Laboratory Analyses (PLA) code for the FRAT® (Folate Receptor Antibody Test) from Religen Inc., a laboratory ELISA that detects anti-human folate receptor IgG binding antibodies and blocking autoantibodies associated with folate metabolism; service type: specialized laboratory diagnostic immunoassay; typical site of service: outpatient clinical laboratory or pathology service performing proprietary testing.

    For related coverage guidance, see recent payer policy updates: Minimal Residual Disease (MRD) Testing for Cancer, Biomarker Testing Mandate, Prenatal (Fetal) Diagnostic Testing.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A pediatric neurology or developmental-behavioral clinic evaluates a 4–8 year-old child with global developmental delay, language regression, and social communication deficits concerning for autism spectrum disorder (ASD). The clinician documents a history of regression and possible response to folinic acid reported in family history. After clinical assessment, the clinician orders the FRAT® (Folate Receptor Antibody Test) to detect anti–human folate receptor IgG binding and blocking autoantibodies that may affect cerebral folate transport. Blood is drawn in the outpatient laboratory; the specimen is sent to Religen Inc. for Proprietary Laboratory Analysis. Results are returned as positive/negative for binding and blocking antibodies with titers, and are reviewed by the ordering clinician to inform discussion of folate metabolism implications in the child’s neurodevelopmental assessment and potential targeted interventions.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    0399UFRAT® (Folate Receptor Antibody Test) — enzyme–linked immunoassay for anti–human folate receptor IgG binding and blocking autoantibodiesPrimary proprietary laboratory analysis described; report when Religen Inc. performs the FRAT® assay.
    80053Comprehensive metabolic panelOften ordered concurrently to assess metabolic baseline and folate-related chemistries during neurodevelopmental evaluation.
    82746Folate; serumComplementary laboratory measurement of serum folate level that may be ordered alongside antibody testing to evaluate folate status.
    81325CYP2D6 gene analysis (example pharmacogenomic test)Example of other specialized laboratory tests that may be ordered in complex neurodevelopmental workups; illustrates laboratory coordination with PLA testing.

    Related Modifiers

    5 rows

    ModifierDescriptionWhen to Use
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    90Modifier ‑90 (Reference/Outside Laboratory) indicates that a laboratory test was performed by an entity other than the treating or reporting provider. The American Medical Association defines…- Use CPT modifier -90 when a laboratory test is performed by an outside/reference laboratory (an entity other than the treating or reporting physician or qualified professional) and the claim needs…

    Related Provider Taxonomies

    8 rows

    Taxonomy Code
    2084P0800X
    2084N0400X
    207Q00000X
    405300000X
    246ZC0007X
    207YX0007X
    1835G0000X
    163WC2100X

    Related ICD-10-CM Codes

    28 rows

    ICD-10-CM CodeDescription
    E53.8Deficiency of other specified B group vitamins
    E53.9Vitamin B deficiency, unspecified
    E55.9Vitamin D deficiency, unspecified
    E63.9Nutritional deficiency, unspecified
    E64.9Sequelae of unspecified nutritional deficiency
    F70Mild intellectual disabilities
    F71Moderate intellectual disabilities
    F72Severe intellectual disabilities
    F73Profound intellectual disabilities
    F80.0Phonological disorder

    Showing 1–10 of 28

    Related Payer Policy Updates

    Specialty: Genetic & Molecular Testing1 / 3

    10 rows

    PolicyPayerEffective Date
    Minimal Residual Disease (MRD) Testing for Cancerregence2027-01-01
    Biomarker Testing MandateBlue Cross Blue Shield - Rhode Island2027-01-01
    Prenatal (Fetal) Diagnostic TestingBlue Cross Blue Shield - Rhode Island2027-01-01
    Oral Cancer Screening and TestingOscar Health2027-01-01
    RTM Testing for Alpha-1 Antitrypsin DeficiencyOscar Health2027-01-01
    Cytochrome P450 Genotype-Guided Treatment Strategy Corporate Medical Policybcbsvermont2027-01-01
    Polygenic Risk ScoreBlue Cross Blue Shield - Rhode Island2026-12-01
    Gene Expression Profiling for Cutaneous MelanomaBlue Cross Blue Shield - Rhode Island2026-12-01
    Genetic Testing for Macular Degenerationregence2026-11-01
    Pharmacogenetic Panel Testing (for Ohio Only)Colorado Rocky Mountain Health Plans2026-11-01

    Related Codes

    CPT-0001U-PRECISETYPE-HEA-MULTIPLEX-RBC-ANTIGEN-GENOTYPING

    CPT 0001U: PreciseType HEA Erythrocyte Antigen Genotyping

    CPT-0002U-POLYPDX-URINE-METABOLOMIC-ASSAY-ADENOMATOUS-POLYP-RISK

    CPT 0002U: PolypDX™ Urine Metabolomic Risk Assay

    CPT-0003U-OVAR-A-NEXT-GENERATION-OVARIAN-CANCER-RISK-ASSAY

    CPT 0003U: Overa (MIA2G) Ovarian Cancer Risk Assay

    CPT-0005U-PROSTATE-EXOSOMEDX-INTELLISCORE-GENE-EXPRESSION-URINE-TEST

    CPT 0005U: ExosomeDx Prostate (IntelliScore) urine gene expression test

    CPT-0007U-TOXPROTECT-URINE-DRUG-SCREEN-WITH-DNA-AUTHENTICATION

    CPT 0007U: ToxProtect Urine Drug Screen With DNA Authentication

    CPT-0008U-H-PYLORI-ANTIBIOTIC-RESISTANCE-SEQUENCING-PANEL

    CPT 0008U: H. pylori Antibiotic Resistance Gene Panel

    CPT-0009U-DEPARRAY-HER2-FISH-TUMOR-CELL-ISOLATION

    CPT 0009U: DEPArray HER2 Tumor‑Cell Isolation with FISH Analysis

    CPT-0010U-BACTERIAL-TYPING-WHOLE-GENOME-SEQUENCING-MAYO-CLINIC

    CPT 0010U: Bacterial Typing by Whole Genome Sequencing, Mayo Clinic

    CPT-0011U-CORDANT-CORE-ALGORITHMIC-ORAL-FLUID-DRUG-TEST

    CPT 0011U: Oral Fluid Drug Test with Algorithmic Steady‑State Comparison

    CPT-0016U-BCR-ABL1-MAJOR-MINOR-FUSION-TRANSCRIPT-TESTING

    CPT 0016U: BCR–ABL1 Major and Minor Breakpoint Fusion Transcripts

    Showing 1–10 of 536

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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