Test Id : SORDB
Sorbitol and Xylitol, Quantitative, Whole Blood
Useful For
Suggests clinical disorders or settings where the test may be helpful
Screening and treatment monitoring for sorbitol dehydrogenase deficiency-related neuropathy.
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
This test is used to aid in the diagnosis and treatment monitoring of patients with sorbitol dehydrogenase-related peripheral neuropathy.
Method Name
A short description of the method used to perform the test
Gas Chromatography Mass Spectrometry (GC-MS) Stable Isotope Dilution Analysis
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
Peripheral neuropathy
Sorbitol
Sorbitol dehydrogenase
Sorbitol dehydrogenase deficiency
SORD
SORD deficiency
SORD deficiency-related neuropathy
SORD-related neuropathy
SORD-related peripheral neuropathy
Xylitol
CMT-SORD
Specimen Type
Describes the specimen type validated for testing
Whole blood
Ordering Guidance
This is a test for diagnosis and treatment monitoring for sorbitol dehydrogenase deficiency-related peripheral neuropathy.
Necessary Information
Biochemical Genetics Patient Information (T602) is recommended, but not required, to be filled out and sent with the specimen to aid in the interpretation of test results.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Patient Preparation:
Fasting: 8 hours, required
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Green top (sodium heparin)
Specimen Volume: 1 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Freeze whole blood specimens in the original tube. Frozen aliquots from well-mixed specimens are also acceptable.
3. Send frozen.
Forms
Biochemical Genetics Patient Information (T602) is recommended, but not required, to be filled out and sent with the specimen to aid in the interpretation of test results.
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.
0.5 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
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 |
|---|---|---|---|
| Whole blood | Frozen (preferred) | 90 days | |
| Refrigerated | 31 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Screening and treatment monitoring for sorbitol dehydrogenase deficiency-related neuropathy.
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
This test is used to aid in the diagnosis and treatment monitoring of patients with sorbitol dehydrogenase-related peripheral neuropathy.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Sorbitol dehydrogenase (SORD) deficiency is an autosomal recessive condition caused by biallelic variants in the SORD gene resulting in peripheral neuropathy, which may present as clinically similar to Charcot-Marie-Tooth disease type 2 or distal hereditary motor neuropathy. The SORD enzyme catalyzes the breakdown of sorbitol to fructose. In patients with SORD deficiency-related peripheral neuropathy, two urine polyols, sorbitol and xylitol, are elevated in both blood and urine when compared to controls. Polyols are sugar alcohols that have been identified in blood, urine, and cerebrospinal fluid. An abnormal blood and urine polyol result suggestive of SORD deficiency-related peripheral neuropathy should be confirmed with molecular genetic analysis. For molecular confirmation, genetic testing for SORD can be performed (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify gene list ID: NEUROLOGY-S3NL4H).
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.
Sorbitol: < or =15.0 nmol/mL
Xylitol: < or =2.0 nmol/mL
Interpretation
Provides information to assist in interpretation of the test results
An interpretive report will be provided.
All profiles are reviewed by the laboratory director and interpretation is based on pattern recognition. A detailed interpretation is given, including an overview of the results and of their significance, a correlation to available clinical information, and recommendations for in vitro confirmatory studies (molecular analysis).
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
A positive test result is diagnostic of sorbitol dehydrogenase (SORD) deficiency-related neuropathy; however, it is strongly recommended to follow-up with molecular analysis. Molecular analysis of the SORD gene is complicated by the SORD2P pseudogene and specific molecular testing approaches may be required to identify both causative variants.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Cortese A, Zhu Y, Rebelo AP, et al. Biallelic mutations in SORD cause a common and potentially treatable hereditary neuropathy with implications for diabetes. Nat Genet. 2020;52(5):473-481. doi:10.1038/s41588-020-0615-4
2. Lassuthova P, Mazanec R, Stanek D, et al. Biallelic variants in the SORD gene are one of the most common causes of hereditary neuropathy among Czech patients. Sci Rep. 2021;11(1):8443. doi:10.1038/s41598-021-86857-0
3. Pons N, Fernandez-Eulate G, Pegat A, et al. SORD-related peripheral neuropathy in a French and Swiss cohort: Clinical features, genetic analyses, and sorbitol dosages. Eur J Neurol. 2023;30(7):2001-2011. doi:10.1111/ene.15793
4. Zhu Y, Lobato AG, Rebelo AP, et al. Sorbitol reduction via govorestat ameliorates synaptic dysfunction and neurodegeneration in sorbitol dehydrogenase deficiency. JCI Insight. 2023;8(10):e164954. Published 2023 May 22. doi:10.1172/jci.insight.164954.
5. Bontrager JE, White AL, Brigatti KW, et al. Urine Sorbitol and Xylitol for the Diagnosis of Sorbitol Dehydrogenase Deficiency-Related Neuropathy. Neurology. 2025;105(11):e214425. doi:10.1212/WNL.0000000000214425
Method Description
Describes how the test is performed and provides a method-specific reference
Fifty microliters of lysed whole blood are spiked with a mixture of labeled internal standards and evaporated. The dry residue is derivatized to form trimethylsilyl ethers, then extracted with hexane. Specimens are analyzed by gas chromatography mass spectrometry, selected ion monitoring using positive ammonia chemical ionization and stable isotope dilution.(Unpublished Mayo method)
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.
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 :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
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 was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
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.
82542
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 |
|---|---|---|
| SORDB | Sorbitol and Xylitol, QN, WB | In Process |
| 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.
|
|---|---|---|
| 623504 | Interpretation | 59462-2 |
| 623502 | Sorbitol | In Process |
| 623503 | Xylitol | In Process |
| 623505 | Reviewed By | 18771-6 |