Hydroxyglutaric Acids, Glutaric Acid, Ethylmalonic Acid, and Methylsuccinic Acid, Blood Spot
Use
This test is useful for evaluating patients with abnormal newborn screens showing elevations of glutarylcarnitine (C5-DC) using dried blood spot specimens. It aids in the differential diagnosis of short-chain acyl-CoA dehydrogenase and isobutyryl-CoA dehydrogenase deficiencies. The test is also used for diagnosing glutaric acidemia type 1 and aiding in the diagnosis of glutaric acidemia type 2. It provides second-tier newborn screening for follow-up of C4-acylcarnitine and glutarylcarnitine (C5DC) elevations, differentiating diagnoses of short-chain Co-A dehydrogenase (SCAD) deficiency, isobutyryl-CoA dehydrogenase (IBDH) deficiency, and ethylmalonic encephalopathy, as well as differentiating diagnoses of glutaric acidemia type I (GA-1) and glutaric acidemia type II (GA-2).
Special Instructions
Patient's age is required for this test. Collection must use sodium heparin or EDTA tubes, and the specimen must be spotted on card the same day as collected. Blood must dry on filter paper at room temperature in a horizontal position for a minimum of 3 hours. Do not stack wet specimens or expose them to heat or direct sunlight; keep specimen dry. Additional instructions are available in English, Spanish, and Chinese.
Limitations
Acylcarnitine analysis cannot differentiate between several isomers. Additional testing of 2-hydroxyglutaric acid, 3-hydroxyglutaric acid, glutaric acid, methylsuccinic acid, and ethylmalonic acid by LC-MS/MS is required for better differentiation among C4-acylcarnitine and glutarylcarnitine/C10-OH isomers. The test also indicates potential results that may show elevated levels of certain acids associated with specific conditions, but may have limitations in individuals who do not present symptoms or those who are low excretors.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 92672-5
- 75037-2
- 82505-9
- 82504-2
- 82503-4
- 82502-6
- 59462-2
- 18771-6
Result Turnaround Time
3-7 days
Related Documents
For more information, please review the documents below
Specimen
Dried Blood Spot
Volume
2 Blood spots
Minimum Volume
1 Blood spot
Container
Card-Blood Spot Collection (Filter Paper)
Collection Instructions
Do not use device or capillary tube containing ACD. Sodium heparin or EDTA are acceptable but must be spotted on card the same day as collected. Completely fill at least 2 circles on the filter paper card (approximately 100 microliters blood per circle). Let blood dry on filter paper at room temperature in a horizontal position for a minimum of 3 hours. Do not stack wet specimens. Do not expose specimen to heat or direct sunlight. Keep specimen dry. For collection instructions, see provided documents in multiple languages.
Causes for Rejection
Blood collected with ACD, nonapproved filter paper, shows serum rings, insufficient specimen.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 123 days |
| Refrigerated | 123 days |
| Frozen | 123 days |