Organic Acids, Urine
Urine organic acid (OA) analysis is indicated when following up infants with a positive newborn screening result, evaluating patients with symptoms of a possible metabolic condition (such as lethargy, vomiting, and failure to thrive), and monitoring individuals diagnosed with a metabolic condition. The assay is sensitive in detecting primary disorders of organic acid metabolism, including many inborn errors of intermediates of amino acids, purines, pyrimidines, and fatty acids. However, the urinary OA pattern can be influenced by age, diet, medication, fasting state, and overall metabolic status. Therefore, information regarding diet, nutrition, medication, and medical history should be provided with the sample for optimal interpretation.
Qualitative organic acid analysis is performed by gas chromatography and mass spectrometry with trimethylsilane derivatization after solvent extraction in urine sample. In many cases, diagnostic work up should also include other metabolic profiles such as plasma amino acids and/or plasma carnitine and acylcarnitine to compile a complete metabolic profile and reach an accurate diagnosis.
- Urine: 5-10 mL (random or preferably morning first void) in a clean container without preservatives, then freeze
- Ideally, specimens should be collected during the time of acute illness as abnormal metabolite levels often decrease, sometimes to near normal concentrations, when the patient is well
- Ship overnight frozen on dry ice
- Routine: 5 days
- Emergency: Same day results available on an emergency basis. Please call the laboratory prior to sending a sample for STAT analysis