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Test Code ALLOI Allo-isoleucine, Blood Spot

Reporting Name

Allo-isoleucine, BS

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Evaluation of newborn screening specimens that test positive for branched-chain amino acids elevations

 

Follow-up of patients with maple syrup urine disease

Method Name

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

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


Specimen Required


Supplies: Card - Blood Spot Collection (Filter Paper) (T493)

Container/Tube:

Preferred: Blood Spot Collection (Filter Paper)

Acceptable: Local newborn screening card, Whatman Protein Saver 903 filter paper, PerkinElmer 226filter paper, Munktell filter paper, Postmortem Screening Card

Specimen Volume: 2 Blood spots

Collection Instructions:

1. Do not use device or capillary tube containing EDTA to collect specimen.

2. At least 1 spot should be complete and unpunched.

3. An alternative blood collection option for a patient older than 1 year is a fingerstick. For detailed instructions, see How to Collect Dried Blood Spot Samples.

4. Include type of feeding information on the collection card.

5. Let blood dry on filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.

6. Do not expose specimen to heat or direct sunlight.

7. Do not stack wet specimens.

8. Keep specimen dry.

Additional Information:

1. For collection instructions see Blood Spot Collection Instructions.

2. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777).

3. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800).


Specimen Type

Whole blood

Specimen 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 shows layering
Serum rings
Multiple applications
Insufficient specimen		 Reject

Reference Values

Allo-isoleucine: <2 nmol/mL

Leucine: 35-215 nmol/mL

Isoleucine: 13-130 nmol/mL

Valine: 51-325 nmol/mL

 

An interpretive report will also be provided.

Interpretation

Allo-isoleucine is nearly undetectable in individuals not affected by maple syrup urine disease (MSUD). Accordingly, its presence is diagnostic for MSUD, and its absence is sufficient to rule-out MSUD.

Day(s) Performed

Monday through Friday

Report Available

2 to 4 days

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

82136

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ALLOI Allo-isoleucine, BS 94571-7

 

Result ID Test Result Name Result LOINC Value
27453 Interpretation 46743-1
27457 Allo-isoleucine 94572-5
27458 Leucine 47679-6
27459 Isoleucine 47671-3
27460 Valine 47799-2
27455 Reviewed By 18771-6