Test Catalog

Test Id : MSUSC

Branched-Chain Amino Acids, Self-Collect, Blood Spot

Useful For
Suggests clinical disorders or settings where the test may be helpful

Monitoring patients with maple syrup urine disease using specimens collected at home


This test is intended for dietary monitoring and follow-up of patients with maple syrup urine disease.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Portions of this test are covered by patents held by Quest Diagnostics

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Branched-Chain Amino Acids, SC, BS

Lists additional common names for a test, as an aid in searching

Branched-Chain Amino Acids (BCAA) Elevations

Maple Syrup Disease

Maple Syrup Urine Disease (MSUD)

Newborn Screen

Newborn Screening

Specimen Type
Describes the specimen type validated for testing

Whole blood

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).


Question ID Description Answers
BG775 Patient Street Address (No PO Box)
BG776 Patient City
BG777 Patient State
BG778 Patient Zip Code
BG779 Patient Country
BG780 Patient Home Phone

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

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

-Dried Blood Spot Collection Tutorial (video)

-Blood Spot Collection Instructions-Fingerstick

-Blood Spot Collection Instructions-Fingerstick-Spanish

Special Instructions
Library of PDFs including pertinent information and forms related to the test


Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1 Blood spot

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Blood spot specimen that shows serum rings or has multiple layers Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Whole blood Ambient (preferred) 59 days FILTER PAPER
Frozen 59 days FILTER PAPER
Refrigerated 59 days FILTER PAPER

Useful For
Suggests clinical disorders or settings where the test may be helpful

Monitoring patients with maple syrup urine disease using specimens collected at home

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Allo-isoleucine: <2 nmol/mL

Leucine: 35-215 nmol/mL

Isoleucine: 13-130 nmol/mL

Valine: 51-325 nmol/mL

Provides information to assist in interpretation of the test results

Quantitative results of allo-isoleucine, leucine, isoleucine, and valine with reference values are reported without added interpretation.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference
Recommendations for in-depth reading of a clinical nature

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/

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

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)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

2 to 4 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 year

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

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
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
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

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
File Definition - Algorithm 2022-12-20
New Test 2022-09-13