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HelpOrder Code SAU Sialic Acid, Free and Total, Random, Urine
Ordering Guidance
This is a recommended screening test for patients suspected to have a diagnosis of free sialic acid storage disease.
Urine oligosaccharides are also recommended for patients with a suspected diagnosis of sialidosis or galactosialidosis.
Necessary Information
Patient's age is required.
Specimen Required
Supplies: Sarstedt 5 mL Aliquot Tube (T914)
Container/Tube: Plastic, 5-mL urine tube
Specimen Volume: 1 mL
Pediatric Volume: 0.5 mL
Collection Instructions: Collect a random urine specimen (early morning preferred).
Forms
1. Biochemical Genetics Patient Information (T602)
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
Useful For
Screening for sialic acid disorders
Genetics Test Information
This is a screening test to detect patients with sialic acid disorders such as free sialic acid storage disorder, sialidosis and galactosialidosis.
Quantitation of free and total sialic acid and the ratio of these are provided.
Special Instructions
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Reporting Name
Sialic Acid, Free and Total, USpecimen Type
UrineSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 90 days |
| Frozen | 90 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
Free Sialic Acid:
≤4 weeks: ≤208 mmol/mol creatinine
5 weeks-12 months: ≤104 mmol/mol creatinine
13 months-18 years: ≤100 mmol/mol creatinine
≥19 years: ≤38 mmol/mol creatinine
Total Sialic Acid
≤4 weeks: ≤852 mmol/mol creatinine
5 weeks-12 months: ≤656 mmol/mol creatinine
13 months-18 years: ≤335 mmol/mol creatinine
≥19 years: ≤262 mmol/mol creatinine
Total/Free Ratio:
≤4 weeks: 1.94-18.68
5 weeks-12 months: 2.34-13.85
13 months-18 years: 2.63-9.18
≥19 years: 3.35-15.81
An interpretive report will also be provided.
Method Description
Sialic acid is measured twice to give a free sialic acid and a total sialic acid value.
Free sialic acid is measured by drying down a 10 mcL aliquot from a random urine collection, reconstitution in 3M hydrochloric acid (HCl) in butanol to give the respective butyl ester. The butyl-ester sialic acid is reconstituted in eluent and submitted for liquid chromatography tandem mass spectrometry analysis.
Total sialic acid is measured by hydrolyzing a 10 mcL aliquot from a random urine collection with HCl. The hydrolyzed sialic acid is then converted to the respective butyl ester with 3M HCl in butanol. The butyl ester sialic acid is reconstituted in eluent and submitted for liquid chromatography tandem mass spectrometry analysis.
Both free and total sialic acid is quantitated using a commercially available stable isotope labeled internal standard from calibration over a concentration range 2.0 to 2000 mcM.(Tebani A, Schlemmer D, Imbard A, Rigal O, Porquet D, Benoist JF. Measurement of free and total sialic acid by isotopic dilution liquid chromatography tandem mass spectrometry method. J Chromatogr B Analyt Technol Biomed Life Sci. 2011;879(31):3694-3699. doi:10.1016/j.jchromb.2011.10.009; Li J, Wu T, Zhang X, Du Y, Wei B, Wang J. Clinical application of liver diseases diagnosis using ultrahigh-sensitive liquid chromatography-mass spectrometry for sialic acids detection. J Chromatogr A. 2022;1666:462837. doi:10.1016/j.chroma.2022.462837)
Day(s) Performed
Friday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
84275