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Test Code HGEM Hydroxyglutaric Acids, Glutaric Acid, Ethylmalonic Acid, and Methylsuccinic Acid, Blood Spot

Reporting Name

HGEM, BS

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Evaluation of patients with an abnormal newborn screen showing elevations of glutarylcarnitine (C5-DC) using dried blood spot specimens

 

Evaluation of patients with abnormal newborn screens showing elevations of C4-acylcarnitine to aid in the differential diagnosis of short-chain acyl-CoA dehydrogenase and isobutyryl-CoA dehydrogenase deficiencies

 

Diagnosis of glutaric acidemia type 1

 

Aiding in diagnosis of glutaric acidemia type 2

Method Name

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


Necessary Information


Patient's age is required.



Specimen Required


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

Container/Tube:

Preferred: Card-Blood Spot Collection (Filter Paper) from heel or finger stick

Acceptable: PerkinElmer (formerly Ahlstrom 226) filter paper, Munktell filter paper, Whatman Protein Saver 903 paper, available newborn screening card, blood collected in tubes containing sodium heparin or EDTA and dried on filter paper

Specimen Volume: 2 Blood spots

Collection Instructions:

1. Do not use device or capillary tube containing ACD to collect specimen. Sodium heparin or EDTA are acceptable but must be spotted on card the same day as collected.

2. Completely fill at least 2 circles on the filter paper card (approximately 100 microliters blood per circle).

3. Let blood dry on filter paper at room temperature in a horizontal position for 3 or more hours.

4. Do not stack wet specimens.

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

6. 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) 123 days FILTER PAPER
  Frozen  123 days FILTER PAPER
  Refrigerated  123 days FILTER PAPER

Reject Due To

Shows serum rings
Insufficient specimen
Blood collected with ACD
Nonapproved filter paper		 Reject

Reference Values

2-OH Glutaric acid: ≤25 nmol/mL

3-OH Glutaric acid: ≤1.5 nmol/mL

Glutaric acid: ≤1.5 nmol/mL

Methylsuccinic acid: ≤0.45 nmol/mL

Ethylmalonic acid: ≤3.5 nmol/mL

Interpretation

Elevations of ethylmalonic acid (EMA) and methylsuccinic acid (MSA) are consistent with a diagnosis of short-chain acyl Co-A dehydrogenase (SCAD) deficiency.

 

Elevation of EMA is consistent with a diagnosis of ethylmalonic encephalopathy.

 

Normal levels of EMA in the context of elevated C4 is consistent with a diagnosis of isobutyryl-CoA dehydrogenase (IBDH) deficiency.

 

Elevation of glutaric acid (GA) and 3-hydroxyglutaric acid (3OH-GA) are consistent with a diagnosis of glutaric acidemia type I (GA1).

 

Elevation of GA, 2-hydroxyglutaric acid (2OH-GA), 3OH-GA, EMA, and MSA are consistent with a diagnosis of glutaric acidemia type II (GA2).

Day(s) Performed

Monday, Wednesday

Report Available

3 to 7 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

83918

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HGEM HGEM, BS 92672-5

 

Result ID Test Result Name Result LOINC Value
36048 2-OH Glutaric acid 75037-2
36049 3-OH Glutaric acid 82505-9
36050 Glutaric acid 82504-2
36051 Methylsuccinic acid 82503-4
36052 Ethylmalonic acid 82502-6
36053 Interpretation (HGEM) 59462-2
36054 Reviewed By 18771-6

Forms

1. Biochemical Genetics Patient Information (T602)

2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.