Diagnosis

Establish or confirm diagnosis

Evaluation of patients with an abnormal newborn screen showing elevations of glutarylcarnitine (C5-DC). 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 … Evaluation of patients with an abnormal newborn screen showing elevations of glutarylcarnitine (C5-DC).   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. View more

Is research allowed on the sample after clinical testing is complete? Help
N/A

An aqueous internal standard is added to the plasma specimen. The supernatant is evaporated under heated nitrogen and the residue is then reconstituted prior to injection onto a liquid chromatography-tandem mass spectrometry (LC-MS/MS). The MS/MS is operated in the multiple reaction monitoring (MRM) negative mode to follow the precursor to … An aqueous internal standard is added to the plasma specimen. The supernatant is evaporated under heated nitrogen and the residue is then reconstituted prior to injection onto a liquid chromatography-tandem mass spectrometry (LC-MS/MS). The MS/MS is operated in the multiple reaction monitoring (MRM) negative mode to follow the precursor to product species transitions. Separation of the structural isomers 2-hydroxyglutaric acid (2OH-GA) and 3-hydroxyglutaric acid (3OH-GA) as well as glutaric acid (GA), ethylmalonic acid (EMA), and methylsuccinic acid (MSA) is accomplished by the optimization of the LC separation. The ratios of the extracted peak areas of GA, EMA, and MSA to their respective internal standards as determined by LC-MS/MS are used to calculate the concentration of each analyte in the sample.(Unpublished Mayo method) View more

Tests performed
Entire test performed in-house

Recovery was used to assess accuracy; mean recovery was 102%. Intra assay precision was performed at 2 levels: CVs (N=20 each) ranged from 3.9%-33.7% where higher CVs were obtained for physiologically low analyte concentrations. Inter assay precision was performed at 2 levels: CVs (N=20 each) ranged from 3.9%-118% where higher … Recovery was used to assess accuracy; mean recovery was 102%. Intra assay precision was performed at 2 levels: CVs (N=20 each) ranged from 3.9%-33.7% where higher CVs were obtained for physiologically low analyte concentrations. Inter assay precision was performed at 2 levels: CVs (N=20 each) ranged from 3.9%-118% where higher CVs were obtained for physiologically low analyte concentrations. The analytical measurement range is analyte dependent and ranges from 0.04 - 15µM. View more

No significant cautionary statements

Is proficiency testing performed for this test? Help
Yes

Method used for proficiency testing: Help
Intra-Laboratory

Description of PT method: Help
Intra-laboratory alternative assessment of performance through quality control or patient blind testing

Description of internal test validation method: Help
This test was laboratory developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements.