Test Id : CRTHS
Double-Stranded DNA (dsDNA) IgG Antibodies, Crithidia luciliae Immunofluorescence Screen, Serum
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluation and management of anti-double-stranded DNA IgG antibodies in patients with clinical features of systemic lupus erythematosus (SLE) or at-risk for disease
This test should not be used independently for the diagnosis and management of patients with SLE.
Reflex Tests
Lists tests that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial tests.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CRTHT | dsDNA Ab IFA Titer, IgG, S | No | No |
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If the double-stranded DNA (dsDNA) IgG antibodies Crithidia luciliae immunofluorescence screen is positive, then the dsDNA IgG antibodies Crithidia luciliae immunofluorescence titer will be performed at an additional charge.
Method Name
A short description of the method used to perform the test
CRTHS, CRTHT: Indirect Immunofluorescence Assay (IFA)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Anti-DNA
Anti ds-DNA
Anti-dsDNA
Anti-double stranded DNA
Antibody to ds-DNA
Antibody to dsDNA
Antibody to double stranded DNA
Connective Tissue Disease
CRITH
Crithidia
CRTHS
CRTHT
DNA Double Stranded
DNA Antibodies
Double Stranded DNA
ds-DNA
ds-DNA Antibodies
ds-DNA by IFA
dsDNA
dsDNA Antibodies
dsDNA by IFA
dsDNA Panel
Lupus
Native Anti-DNA
Native DNA
Native ds-DNA
Native dsDNA
SLE
Systemic Lupus Erythematosus
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If the double-stranded DNA (dsDNA) IgG antibodies Crithidia luciliae immunofluorescence screen is positive, then the dsDNA IgG antibodies Crithidia luciliae immunofluorescence titer will be performed at an additional charge.
Specimen Type
Describes the specimen type validated for testing
Serum
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.8 mL Serum
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
See Specimen Required
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | OK |
| Heat-treated | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 21 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluation and management of anti-double-stranded DNA IgG antibodies in patients with clinical features of systemic lupus erythematosus (SLE) or at-risk for disease
This test should not be used independently for the diagnosis and management of patients with SLE.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If the double-stranded DNA (dsDNA) IgG antibodies Crithidia luciliae immunofluorescence screen is positive, then the dsDNA IgG antibodies Crithidia luciliae immunofluorescence titer will be performed at an additional charge.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Anti-double-stranded DNA (anti-dsDNA) antibodies are a hallmark serological marker for systemic lupus erythematosus (SLE), with high specificity that makes them crucial for diagnosing and classifying the disease, particularly under the 2012 Systemic Lupus International Collaborating Clinics and 2019 European Alliance of Associations for Rheumatology/American College of Rheumatology criteria.(1-3) Clinically, these antibodies are not just diagnostic but are strongly associated with disease activity and the pathogenesis of severe complications, most notably lupus nephritis (LN), as their titers often rise just before or during clinical flares.(4-7)
The frequently used methods for detection and quantification of anti-dsDNA antibody in the clinical laboratory include the solid-phase immunoassays (SPAs) such as the enzyme linked immunosorbent assay (ELISA), fluoro-enzyme immunoassay, chemiluminescence immunoassay, multiplexed bead-based assays and indirect immunofluorescence test using Crithidia luciliae (CLIFT) as substrate.(8) The Farr radioimmunoassay (RIA) is traditionally considered a "gold standard" for detecting anti-dsDNA antibody testing as it selectively detects high avidity antibodies, uses native antigen, and has high specificity. However, the Farr-RIA has largely been replaced by manual or automated solid-phase immunoassays and CLIFT.
The CLIFT is a highly specific diagnostic tool used primarily for the confirmation of medium-to-high avidity and medium-to-high affinity anti-dsDNA IgG antibodies.(3) By utilizing the kinetoplast of the non-pathogenic hemoflagellate Crithidia luciliae, which contains a dense, pure concentration of circular double-stranded DNA (dsDNA), the assay provides a unique substrate free from contaminating nuclear antigens like histones or single-stranded DNA.(8) While its sensitivity is moderate (approximately 42%-76%), its specificity for SLE is nearly 98% to 100%, making it an essential "rule-in" test after an initial positive result from more sensitive but less specific SPAs like ELISA.
Beyond its role in SLE diagnosis, the CLIFT carries significant clinical weight in assessing disease activity and organ involvement.(4,6,7) Positive results are strongly linked to active SLE and LN, and associated with complement consumption.(9,10) Because the CLIFT preferentially detects medium-to-high avidity and medium-to-high affinity IgG antibodies, a positive titer is frequently associated with periods of disease flare, whereas a negative result may occur during remission even if other assays remain positive. Consequently, clinicians use the CLIFT to assess risk for disease remission and specific clinical manifestations, as high titers often drop in response to successful immunosuppressive therapy. However, due to its high specificity but low sensitivity, the CLIFT is widely used as a confirmatory test following a positive anti-dsDNA IgG result obtained in a SPA.(4-8)
Discordant results between SPAs as well as SPAs and CLIFT for anti-dsDNA antibodies is relatively common (3-5,7-8), occurring in a fifth of patients overall and a third of visits.(7)
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
DOUBLE-STRANDED DNA (dsDNA) IgG ANTIBODIES, CRITHIDIA LUCILIAE IMMUNOFLUORESCENCE SCREEN
Negative (<1:10)
Reference values apply to all ages.
DOUBLE-STRANDED DNA (dsDNA) IgG ANTIBODIES, CRITHIDIA LUCILIAE IMMUNOFLUORESCENCE TITER
Negative (<1:10)
Interpretation
Provides information to assist in interpretation of the test results
The presence of IgG antibodies to double-stranded DNA detected using the Crithidia luciliae indirect immunofluorescence test is highly specific for systemic lupus erythematosus (SLE) with moderate sensitivity.
A negative result does not exclude a diagnosis of SLE.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
IgG antibodies to double-stranded DNA (dsDNA) using the Crithidia luciliae by indirect immunofluorescence test (CLIFT) should not be relied upon exclusively to diagnose and manage patients with systemic lupus erythematosus (SLE).
Compared to some solid-phase immunoassays, CLIFT is specific but lacks diagnostic sensitivity for SLE. A more sensitive semi-quantitative enzyme linked immunosorbent assay for assessing IgG antibodies to dsDNA is also available, see test ADNA1 / Double-Stranded DNA (dsDNA) Antibodies, IgG, Serum.
A negative result does not exclude a diagnosis of SLE.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Petri M, Orbai AM, Alarcon GS, et al. Derivation and validation of the Systemic Lupus International Collaborating Clinics classification criteria for systemic lupus erythematosus. Arthritis Rheum. 2012;64(8):2677-2686
2. Aringer M, Costenbader K, Daikh D, et al. 2019 European League Against Rheumatism/American College of Rheumatology Classification Criteria for systemic lupus erythematosus. Arthritis Rheumatol. 2019;71(9):1400-1412
3. Orme ME, Voreck A, Aksouh R, Schreurs MWJ. Anti-dsDNA Testing Specificity for Systemic Lupus Erythematosus: A systematic review. J Appl Lab Med. 2022;7(1):221-239. doi:10.1093/jalm/jfab146
4. Enocsson H, Sjowall C, Wirestam L, et al. Four anti-dsDNA antibody assays in relation to systemic lupus erythematosus disease specificity and activity. J Rheumatol. 2015;42(5):817-825
5. Sarbu MI, Salman-Monte TC, Rubio Munoz P, Lisbona MP, Almirall Bernabe M, Carbonell J. Differences between clinical and laboratory findings in patients with recent diagnosis of SLE according to the positivity of anti-dsDNA by the Crithidia luciliae method. Lupus. 2015;24(11):1198-1203
6. Bragazzi NL, Watad A, Damiani G, Adawi M, Amital H, Shoenfeld Y. Role of anti-DNA auto-antibodies as biomarkers of response to treatment in systemic lupus erythematosus patients: hypes and hopes. Insights and implications from a comprehensive review of the literature. Expert Rev Mol Diagn. 2019;19(11):969-978
7. Zaminski D, Saxena A, Izmirly P, Buyon JP, Belmont HM. Clinical implications of discordance between anti-dsDNA antibodies by multiplex flow immunoassay and Crithidia luciliae assay in a multiethnic racial cohort of patients with SLE. Lupus Sci Med. 2023;10(2):e001012
8. Cockx M, Van Hoovels L, De Langhe E, et al. Laboratory evaluation of anti-dsDNA antibodies. Clin Chim Acta. 2022;528:34-43
Method Description
Describes how the test is performed and provides a method-specific reference
Crithidia luciliae Immunofluorescence Test Screen:
Patient serum is diluted 1:10 and allowed bind to the kinetoplast of the non-pathogenic hemoflagellate Crithidia luciliae adhered to the slide. The Crithidia luciliae contains a dense, pure concentration of circular double-stranded DNA that provides a unique substrate free from contaminating nuclear antigens like histones or single-stranded DNA. Following binding, unbound diluted patient serum is washed off the slide and fluorescent-conjugated antiserum added to the substrate on the slide and incubated. A second washing step is performed to remove excess conjugate. The substrate is cover slipped and reviewed for fluorescent patterns with a fluorescent microscope. Observation of specific fluorescent patterns on the substrate indicate the presence of autoantibodies in the test sample.(Package insert: Immuno Concepts IgG ANTI-nDNA Fluorescent Test System. Immuno Concepts; Rev 4.0, 2023)
Crithidia luciliae Immunofluorescence Test Titer:
Patient serum with a positive screen at the 1:10 dilution is titered up to 1:640 and allowed to bind to the kinetoplast of the non-pathogenic hemoflagellate Crithidia luciliae adhered to the slide. The Crithidia luciliae contains a dense, pure concentration of circular double-stranded DNA that provides a unique substrate free from contaminating nuclear antigens like histones or single-stranded DNA. Following binding, unbound diluted patient serum is washed off the slide and fluorescent-conjugated antiserum added to the substrate on the slide and incubated. A second washing step is performed to remove excess conjugate. The substrate is cover slipped and reviewed for fluorescent patterns with a fluorescent microscope. Observation of specific fluorescent patterns on the substrate indicate the presence of autoantibodies in the test sample. Positive results are reported with an end point titer up to 1:640. Results higher than 1:640 are reported as greater than 1:640.(Package Insert: Immuno Concepts IgG ANTI-nDNA Fluorescent Test System, Immuno Concepts, Rev 4.0 2023)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Friday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees
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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
86255
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| CRTHS | dsDNA Ab IFA Screen, IgG, S | 6457-6 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 623426 | dsDNA Ab IFA Screen, IgG, S | 6457-6 |
| 623463 | dsDNA Interpretation | 69048-7 |