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Test ID: SORDB Sorbitol and Xylitol, Quantitative, 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


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.

Useful For

Screening and treatment monitoring for sorbitol dehydrogenase deficiency-related neuropathy.

Genetics Test Information

This test is used to aid in the diagnosis and treatment monitoring of patients with sorbitol dehydrogenase-related peripheral neuropathy.

Method Name

Gas Chromatography Mass Spectrometry (GC-MS) Stable Isotope Dilution Analysis

Reporting Name

Sorbitol and Xylitol, QN, WB

Specimen Type

Whole blood

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole blood Frozen (preferred) 90 days
  Refrigerated  31 days

Clinical Information

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

Sorbitol: ≤15.0 nmol/mL

Xylitol: ≤2.0 nmol/mL

Interpretation

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).

Clinical Reference

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

Day(s) Performed

Friday

Report Available

5 to 11 days

Test Classification

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

82542

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SORDB Sorbitol and Xylitol, QN, WB In Process

 

Result ID Test Result Name Result LOINC Value
623504 Interpretation 59462-2
623502 Sorbitol In Process
623503 Xylitol In Process
623505 Reviewed By 18771-6
Mayo Clinic Laboratories | Genetics and Genomics Additional Information:

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