Overview: Threonine (Urine) TestIntroduction: The Threonine (Urine) Test tests threonine in urine to diagnose metabolic disorders, helping identify causes of developmental delays or kidney issues. Affecting 1 in 50,000 people, metabolic disorders pose diagnostic challenges due to diverse symptoms. Following 2023 Clinical and Laboratory Standards Institute (CLSI) guidelines, it uses LC-MS/MS for high accuracy, supporting biochemistry screening. This test is vital for diagnosis, treatment planning, and improving outcomes in metabolism.
Other Names: Urine Threonine Test, Amino Acid Excretion Assay.
FDA Status: Laboratory-developed test (LDT), meeting biochemistry standards for diagnostic reliability.
Historical Milestone: Threonine urine testing began in the 1970s with research by Scriver, who linked it to metabolism. LC-MS/MS advancements by Agilent improved detection, surpassing earlier HPLC methods.
Purpose: Tests threonine levels in urine to diagnose metabolic disorders, guides dietary or supportive therapy, and evaluates patients with developmental delays, aiming to manage symptoms.
Test Parameters: Threonine levels
Pretest Condition: No special preparation required. Collect urine. Report history of metabolic issues.
Specimen: Urine (sterile container, 5-20 mL); 10 mL urine in sterile container. 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 kidney issues. Include current medications or family history.
Consent: Written consent required, detailing the test's purpose, disease risks (e.g., kidney failure), and sample collection risks.
Procedural Considerations: Uses LC-MS/MS to measure levels, 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: Abnormal levels suggest metabolic disorders, guiding therapy. Early treatment might prevent complications, while untreated cases lead to worsening. Normal levels may require other tests.
Specialist Consultation: Consult a metabolic specialist for interpretation.
Additional Supporting Tests: Plasma amino acids, urine organic acids, or genetic panel to confirm diagnosis.
Test Limitations: Non-specific for cause; correlation with clinical status needed. False results possible with improper collection.
References: CLSI Guidelines, 2023; Journal of Pediatrics, Scriver CR, 2022.
