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Test ID: Second-tier Methylmalonic Acid, 2-Methylcitric Acid Screening and Ethylmalonic acid Dried blood spot
Second-tier Methylmalonic Acid, 2-Methylcitric Acid Screening and Ethylmalonic acid Dried blood spot
Internal Reflex Test: Second-tier assay of newborn screening specimens when abnormal propionyl carnitine or methionine and Homocysteine (Total) concentrations are identified in a primary newborn screen.
Useful For

Internal Reflex Test: Second-tier assay of newborn screening specimens when abnormal Propionylcarnitine (C3), Total homocysteine or Butyryl/Isobutyrlcarnitine (C4) concentrations are identified in the primary newborn screening.

Method name and description

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

Reporting name

Methylmalonic acid (MMA)

Methylcitric acid (MCA)

Ethylmalonic acid (EMA)

Clinical information

Improve performance of newborn screening for propionylcarnitine-related disorders.  

Aliases
Specimen type / Specimen volume / Specimen container

Specimen type: Whole blood collected from heel prick with direct application onto special Whatman 903 filter paper.

Specimen Volume: 5 Circles(spot) if ordered with the whole screening panel. Minimum 3 spot if requested alone i.e., successive collection.                                  

Specimen container: Newborn screening Blood Spot Collection Card 

   

        

Collection instructions / Special Precautions / Timing of collection

Collection instructions:

1.Collect blood for newborn screening at 24 hours of age.

2.Complete the required patient information on the collection card and ensure that the expiration date of the collection card has not passed.

3.Collect blood from the most medial or lateral portion of the plantar surface of the heel; allow blood to soak through to completely fill each of the preprinted circles; do not apply layers of successive blood drops to the same printed circle; inspect both sides of the collection card to be sure blood is soaked through to the back of the card.

4.Allow blood specimen to air dry for a minimum of three hours on a horizontally level, nonabsorbent, open surface at an ambient temperature of 18 to 25 °C.

5. Fold-over cover provides protection from contamination before blood collection, during specimen transportation and during specimen storage after analysis. Blood spots must be thoroughly dry before the flap is closed over spots.

6.The collection card/dried blood specimen should be transported to the laboratory with the appropriate tracking documentation and within 24 hours of collection.

Special Precautions

1.Premature infants who are less than 32 weeks of gestational age, screening must be repeated after the infant completes 32 weeks.  

2.In case of immediate blood transfusion, exchange transfusion, treatment with corticosteroids or dopamine initial specimen must be collected even if the newborn less than 24 hrs of age and repeated after 5 days of discontinuation of drug or last transfusion.

 

Relevant clinical information to be provided

omplete the required demographic information on the blood spot collection card. 

Storage and transport instructions

Ambient.

The dried blood specimens must  be transported to the laboratory every working day with appropriate tracking documentation.

Specimen Rejection Criteria

Specimen collected 24 hours before newborn age

Insufficient quantity of blood.

Blood spots appear scratched or abraded.

Blood spots are wet and/or discolored/diluted.

Blood spots are supersaturated.

Blood spots exhibit serum rings.

Blood spots appear clotted or layered.

Blood spots were damaged or delayed in transit.

Utilizing expired blood cards.

Delayed (old) specimen > seven (7) days from collection.

Missing and/or inaccurate demographic information.

Anticoagulants (EDTA, citrate) will interfere with some newborn screening tests

Biological reference intervals and clinical decision values

Methylmalonic acid (MMA)    < 5.0 µmol/L

Methylcitric acid ( MCA)        < 3.0 µmol/L

Ethylmalonic acid (EMA)      < 4.00 µmol/L

Factors affecting test performance and result interpretation
Turnaround time / Days and times test performed / Specimen retention time

Turnaround time : 7 days 

Specimen retention time: 2-8°C for 2 years, long-term storage at ambient temperature for indefinitely.