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Order Code LABGOR, SORBU Sorbitol and Mannitol, Quantitative, Random, Urine

Additional Codes

Order EPIC Test Code: LABGOR with Mayo Test ID: SORBU


Ordering Guidance


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



Necessary Information


Patient's age is required.



Specimen Required


Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 2 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.


Forms

If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.

Useful For

Monitoring effectiveness of treatment in patients with phosphomannomutase 2 deficiency (PMM2-CDG)

 

Establishing a baseline level prior to initiating treatment for PMM2-CDG

 

This test is not useful for diagnosing congenital disorders of glycosylation (CDG) in general or PMM2-CDG in particular

Method Name

Gas Chromatography Mass Spectrometry (GC-MS)

Reporting Name

Sorbitol and Mannitol, QN, U

Specimen Type

Urine

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 28 days
  Frozen  28 days

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

Mannitol: <97 mmol/mol creatinine

Sorbitol: <35 mmol/mol creatinine

Method Description

A total of 200 mcL of urine is spiked with a mixture of labeled internal standards, allowed to equilibrate, and evaporated. The dry residue is derivatized to form trimethylsilyl esters, then extracted with hexane. Specimens are analyzed by gas chromatography mass spectrometry, selected ion monitoring using ammonia chemical ionization and a stable isotope dilution method.(Jansen G, Muskiet F, Schierbeek H, et al. Capillary gas chromatography profiling of urinary, plasma, and erythrocyte sugars and polyols as their trimethylsilyl derivatives, preceded by a simple and rapid prepurification method. Clin Chim Acta. 1986;157[3]:277-294; Marolt G, Kolar M. Analytical methods for determination of phytic acid and other inositol phosphates: A review. Molecules. 2020;26[1]:174)

Day(s) Performed

Tuesday, Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82542