Overview: Argininosuccinic Acid TestIntroduction: The Argininosuccinic Acid Test tests for high levels of a substance indicating Argininosuccinic Aciduria, a rare disorder causing developmental delays, seizures, or liver problems in children, aiding early diagnosis. Affecting 1 in 100,000 newborns, this metabolic disorder poses diagnostic challenges due to its nonspecific symptoms. Following 2023 Society for Inherited Metabolic Disorders (SIMD) guidelines, it uses LC-MS/MS for high accuracy, supporting biochemistry screening. This test is vital for diagnosis, treatment planning, and improving outcomes in pediatrics.
Other Names: ASA Level Test, Argininosuccinic Aciduria Assay.
FDA Status: Laboratory-developed test (LDT), meeting biochemistry standards for diagnostic reliability.
Historical Milestone: Metabolic testing began in the 1960s with research by Brusilow, who identified ASA in urea cycle disorders. LC-MS/MS advancements in the 2000s by companies like Waters improved detection, surpassing earlier amino acid analysis methods.
Purpose: Measures argininosuccinic acid levels to diagnose Argininosuccinic Aciduria, guides ammonia-lowering therapy, and evaluates children with developmental delays or seizures, aiming to prevent neurological damage.
Test Parameters: Argininosuccinic acid levels
Pretest Condition: No special preparation required. Collect plasma or urine. Report history of developmental issues.
Specimen: Plasma (NaHep, 2-4 mL), Urine (sterile container, 5-20 mL); 10 mL urine in sterile container or 2 mL plasma in Na Heparin tube. Transport in a biohazard container.
Sample Stability at Room Temperature: 4 hours
Sample Stability at Refrigeration: 48 hours
Sample Stability at Frozen: 1 month
Medical History: Document developmental delays or seizures. Include current medications or family history of metabolic disorders.
Consent: Written consent required, detailing the test's purpose, disease risks (e.g., coma), and sample collection risks.
Procedural Considerations: Uses LC-MS/MS to measure ASA, requiring labs with mass spectrometers. Results available in 2-3 days. Performed in labs with strict handling.
Factors Affecting Result Accuracy: Sample degradation or contamination can affect results. Medications may alter levels, requiring correlation.
Clinical Significance: Elevated ASA confirms Argininosuccinic Aciduria, guiding therapy. Early treatment might prevent coma, while untreated cases lead to death. Normal levels may require ammonia tests.
Specialist Consultation: Consult a pediatrician or metabolic specialist for interpretation.
Additional Supporting Tests: Ammonia level, urine orotic acid, or genetic testing to confirm diagnosis.
Test Limitations: Non-specific for severity; correlation needed. False negatives possible with sample issues.
References: SIMD Guidelines, 2023; Journal of Inherited Metabolic Disease, Brusilow SW, 2022.
