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Test ID SORD Sorbitol and Xylitol, Quantitative, Random, Urine


Ordering Guidance


This is the preferred test for assessing sorbitol dehydrogenase (SORD) deficiency-related peripheral neuropathy. The preferred test for monitoring effectiveness of treatment in patients with phosphomannomutase 2 deficiency (PMM2-CDG) is SORBU / Sorbitol and Mannitol, Quantitative, Random, Urine



Necessary Information


1. Patient’s age is required.

2. 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


Supplies: Urine Tubes, 10mL (T068)

Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 2 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative needed.


Secondary ID

620920

Useful For

Screening for sorbitol dehydrogenase deficiency-related neuropathy

Method Name

Gas Chromatography Mass Spectrometry (GC-MS)

Reporting Name

Sorbitol and Xylitol, QN, U

Specimen Type

Urine

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 28 days
  Frozen  28 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, the urine polyols, sorbitol and xylitol, are elevated when compared to controls. Polyols are sugar alcohols that have been identified in blood, urine, and cerebrospinal fluid. An abnormal 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:

<35 mmol/mol creatinine

 

Xylitol:

<351 mmol/mol creatinine

Cautions

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 maybe required.

Day(s) Performed

Tuesday

Report Available

3 to 9 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

NY State Approved

Yes