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HelpTest ID: MSUSC Branched-Chain Amino Acids, Self-Collect, Blood Spot
Necessary Information
Patient's street address, city, state, ZIP (postal) code, country, and home phone are required (post-office [PO] boxes are not acceptable delivery locations).
Specimen Required
Supplies: Blood Spot Collection-Self Collect (T858)
Container/Tube: Blood Spot Self Collection Card
Specimen Volume: 2 Blood spots
Collection Instructions:
1. Order test each time the patient is to collect a dried blood specimen at home and mail the specimen directly to Mayo Clinic Laboratories.
2. Order should be placed a minimum of 3 days prior to desired date of collection.
3. Enter patient's address information for each order created, including street address (post-office [PO] boxes are not acceptable delivery locations), city, state abbreviation, ZIP (postal) code, country, and home phone number.
4. For each order, the Blood Spot Collection-Self Collect kit will be mailed directly to the patient for self-collection (delivery to a PO box will not occur).
5. For more information on how to collect blood spots, see the following:
-How to Collect Dried Blood Spot Samples via fingerstick.
-Blood Spot Collection Instructions-Fingerstick
-Blood Spot Collection Instructions-Fingerstick-Spanish
Useful For
Monitoring patients with maple syrup urine disease using specimens collected at home
Method Name
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Portions of this test are covered by patents held by Quest Diagnostics
Reporting Name
Branched-Chain Amino Acids, SC, BSSpecimen Type
Whole bloodSpecimen Minimum Volume
1 Blood spot
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Ambient (preferred) | 59 days | FILTER PAPER |
| Frozen | 59 days | FILTER PAPER | |
| Refrigerated | 59 days | FILTER PAPER |
Clinical Information
Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by the deficiency of the branched-chain-ketoacid dehydrogenase (BCKDH) complex. The BCKDH complex is involved in the metabolism of the branched-chain amino acids (BCAA): isoleucine (Ile), leucine (Leu), and valine (Val). Classic MSUD presents in the neonate with feeding intolerance, failure to thrive, vomiting, lethargy, and maple-syrup odor to urine and cerumen. If untreated, it progresses to irreversible intellectual disability, hyperactivity, failure to thrive, seizures, coma, cerebral edema, and possibly death.
Treatment of MSUD aims to normalize the concentration of BCAA by dietary restriction of these amino acids. BCAA are essential amino acids that require frequent adjustment of the dietary treatment. Dietary monitoring is accomplished by regular determination of BCAA and Allo-Ile concentrations.
Reference Values
Allo-isoleucine: <2 nmol/mL
Leucine: 35-215 nmol/mL
Isoleucine: 13-130 nmol/mL
Valine: 51-325 nmol/mL
Interpretation
Quantitative results of allo-isoleucine, leucine, isoleucine, and valine with reference values are reported without added interpretation.
Clinical Reference
1. Morton DH, Strauss KA, Robinson DL, Puffenberger EG, Kelley RI: Diagnosis and treatment of maple syrup disease: a study of 36 patients. Pediatrics. 2002 Jun;109(6):999-1008. doi: 10.1542/peds.109.6.999
2. Strauss KA, Puffenberger EG, Carson VJ: Maple syrup urine disease. In: Adam MP, Ardinger HH, Pagon RA, et al. eds. GeneReviews [Internet]. University of Washington, Seattle; 2006. Updated April 23, 2020. Accessed June 21, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK1319/
Day(s) Performed
Monday through Friday
Report Available
2 to 4 daysTest 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
0381U
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| MSUSC | Branched-Chain Amino Acids, SC, BS | 94571-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 618731 | Allo-isoleucine | 94572-5 |
| 618732 | Leucine | 47679-6 |
| 618733 | Isoleucine | 47671-3 |
| 618734 | Valine | 47799-2 |
| 618730 | Reviewed By | 18771-6 |
| BG775 | Patient Street Address (No PO Box) | 56799-0 |
| BG776 | Patient City | 68997-6 |
| BG777 | Patient State | 46499-0 |
| BG778 | Patient Zip Code | 45401-7 |
| BG779 | Patient Country | 77983-5 |
| BG780 | Patient Home Phone | 42077-8 |
Forms
If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
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