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Diagnostic Services

Genetics Lab


Maple Syrup Urine Disease (MSUD) Monitoring

Maple syrup urine disease (MSUD) is a disorder of amino acid metabolism. Affected individuals can have repeated episodes of vomiting, lethargy, and encephalopathy. The disorder is named for the characteristic smell of burnt sugar or maple syrup in the urine and tissues. Disposable diapers and diaper creams are also known to cause a maple syrup odor in normal individuals. Typically, individuals with MSUD have elevated leucine, isoleucine, valine and alloleucine in their blood in a specific ratio.

MSUD affects approximately 1:300 000 individuals and is detected as part of the Washington State newborn screening program.

Test Name: MSUD Monitoring
Test Code:
Test Description:
Quantitative analysis of leucine, isoleucine, valine and alloisoleucine in plasma.
amino acid; leucine; isoleucine; valine; alloisoleucine
This test is used to monitor known MSUD patients. This test measures leucine, isoleucine, valine and alloiloleucine.
Related Tests: Amino Acids, Quantitative  
This test is for confirmation of newborn screening results, evaluating patients with episodes of lethary or vomiting suggestive of a metabolic disorder and for follow-up of known patients for assessment of management.

Clinical Links: MSUD GeneReview
Set up daily. Available STAT by special arrangement.
Turnaround Time:
1-2 days
Reference Range:
Reference ranges vary with age and accompany patient results
Consent Form:
Sample Requirements: Type
Whole blood: 2ml heparin (green). No gel separator tubes

Spin blood, freeze plasma.

Overnight shipping, keep frozen.
Samples Received:
Mon – Fri 8:00 am – 5:00 pm PST
Special Considerations:
Please e-mail Client Services or call at 206-987-2617 with any billing questions
CPT Code:
Please e-mail Client Services or call at 206-987-2617 with any billing questions