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HelpTest Code 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 |
Reject Due To
| Blood spot specimen that shows serum rings or has multiple layers | Reject |
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.
Cautions
No significant cautionary statements
Method Description
This method quantifies valine (Val), allo-isoleucine (Allo-Ile), isoleucine (Ile), and leucine (Leu) using stable isotope-labeled internal standards (IS): d8-Val, d10-Allo-Ile, and d3-Leu. Branched-chain amino acids (BCAA) are extracted from a 3/16-inch dried blood spot (DBS) using a methanol:water (50:50) solution containing the IS. The filter plate containing the DBS and the IS are placed on an orbital shaker for 30 minutes at ambient temperature. The blood spot eluate is centrifuged into a 96-well round-bottom plate, dried under nitrogen, and reconstituted in aqueous mobile phase. BCAA are separated and detected by liquid chromatography-tandem mass spectrometry in positive selected reaction monitoring mode.(Oglesbee D, Kramer K, Lacey J, et al: Second-tier test for quantification of alloisoleucine and branched-chain amino acids in dried blood spots to improve newborn screening of maple syrup urine disease [MSUD]. Clin Chem. 2008 Mar;54(3):542-549. doi: 10.1373/clinchem.2007.098434; Stroek K, Boelen A, Bouva MJ, et al: Evaluation of 11 years of newborn screening for maple syrup urine disease in the Netherlands and a systematic review of the literature: Strategies for optimization. JIMD Rep. 2020 May 13;54(1):68-78. doi: 10.1002/jmd2.12124)
Day(s) Performed
Monday through Friday
Report Available
2 to 4 daysPerforming 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
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 |