Amino Acid Analysis, Cerebral Spinal Fluid (CSF) (Test 1300)

CPT Code(s): 82139

Ordering Recommendation: This test is intended to be used in the detection of multiple different inborn errors of metabolism including those affecting amino acid metabolism/transport, creatine metabolism, sulfite intoxication, and peroxisomal biogenesis. A common indication for cerebral spinal fluid (CSF) amino acid testing is suspected nonketotic hyperglycinemia (OMIM 605899). In this case, it is critical to also draw plasma concurrently with the CSF collection. This plasma should also be submitted for amino acid analysis to allow a calculation of CSF glycine to plasma glycine ratio. Plasma samples drawn separately (> 1 hour apart) from CSF collection can NOT be used for ratio calculations.

Synonyms: CSF-AA

Methodology: Liquid chromatography tandem mass spectrometry (LC-MS/MS)

Performed: Monday through Friday

Reported: 2-7 days

Patient Preparation: When collecting specimens for CSF amino acid analysis, it is generally a good idea in all cases to concurrently collect a plasma specimen for plasma amino acid analysis.

When non-ketotic hyperglycinemia (OMIM 605899) is suspected, a ratio of glycine in plasma vs CSF can be important for diagnosis. In this case, it is required that plasma and CSF are collected concurrently.

Specimen Type: CSF

Collection Tube (preferred): tube free of preservatives or other additives

Collection Tube (other acceptable): none

Processing: CSF should be stored at -20°C as soon as possible after collection. CSF should appear clear and free of pink/yellow/red coloration that would indicate contamination with blood. Contaminated CSF samples will be analyzed by the lab and charged to the client, but results will most likely be uninterpretable.

Specimen Volume: 0.5 mL (minimum of 0.1 mL)

Storage: -20°C

Shipment: Ship frozen samples on 3-5 lbs of dry ice in an insulated container using an overnight courier.

Unacceptable Conditions:

• Specimen requirements listed above are not met.
• Sample has fully thawed during shipment.
• Discolored CSF specimens are a common issue indicating specimen contamination with blood or plasma. CSF-AA results from contaminated samples are often falsely elevated and therefore uninterpretable. Avoid sending discolored CSF specimens.

Stability: 30 days in freezer (-20°C) 

Interpretation: A brief interpretation of results is provided with each test.

Limitations: False negative results can occur in rare situations when diet and/or clinical condition masks or normalizes disease relevant analyte perturbations.  In addition, false negatives may occur when disease presentation is intermittent or the result of a mild defect.

Results should be viewed in the context of clinical presentation and concurrent laboratory studies. In the case of a new diagnosis, results should be confirmed with additional biochemical or molecular genetic testing.

This test was developed and its performance characteristics determined by Indiana University Biochemical Genetics Laboratory. It has not been cleared or approved by the U.S. Food and Drug Administration. This test is used for clinical purposes. It should not be regarded as investigational or for research. The laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA ’88) as qualified to perform high complexity clinical laboratory testing. CLIA # 15D0647198, CAP# 1678930 

Reference Range:

Scroll/swipe this table left and right to see more information.

*All values in micromoles/L

References:

1. Prinsen H.C.M.T, B.G.M. Schiebergen-Bronkhorst, M.W. Roeleveld, J.J.M. Jans,M.G.M de Sain-van der Velden, G. Visser, P.M. van Hasselt, N.M Verhoeven-Duif. “Rapid quantification of underivatized amino acids in plasma by hydrophilic interaction liquid chromatography (HILIC) coupled with tandem massspectrometry”. J Inherit Metab Dis 39(5):651-660
2. Griffin, C., Z. Ammous, G. H. Vance, B. H. Graham and M. J. Miller (2019). "Rapid quantification of underivatized alloisoleucine and argininosuccinate using mixed-mode chromatography with tandem mass spectrometry." J Chromatogr B Analyt Technol Biomed Life Sci 1128: 121786.