Sign in →

Order Code ALLOI Allo-isoleucine, Blood Spot

Reporting Name

Allo-isoleucine, BS

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

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Whole blood


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 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

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.

Day(s) Performed

Monday through Friday

CPT Code Information

82136

Genetics Test Information

Second-tier test for abnormal newborn screen and follow-up of patients with maple syrup urine disease.

Method Description

This method quantifies valine (Val), allo-isoleucine (Allo-Ile), leucine (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;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;54(1):68-78. doi:10.1002/jmd2.12124)

Reject Due To

Blood spot shows layering
Serum rings
Multiple applications
Insufficient specimen		 Reject

Method Name

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

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