3-O-Methyldopa (Plasma)

CPT: 82131
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Special Instructions

This assay is not currently available in New York state.


Expected Turnaround Time

10 - 14 days



Specimen Requirements


Specimen

Plasma, frozen


Volume

1.0 mL


Minimum Volume

0.5 mL


Container

Lavender-top (EDTA) tube, green-top (sodium heparin) tube


Collection

Collect 2-4 mL blood in sodium heparin (green-top) or EDTA (purple-top) tube.


Storage Instructions

Remove plasma and freeze at -20°C. Store frozen at -20°C and ship frozen.


Stability Requirements

Temperature

Period

Room temperature

Unstable

Refrigerated

Unstable

Frozen

Indefinitely


Causes for Rejection

Thawed sample


Test Details


Use

Aromatic L-amino acid decarboxylase (AADC) is a pyridoxal 5'-phosphate dependent enzyme responsible for the formation of dopamine and serotonin. AADC deficiency is a congenital autosomal recessive metabolic disorder that causes hypotonia, hypokinesia, oculogyric crises, and signs of autonomic dysfunction beginning in infancy. In AADC deficiency, L-dopa accumulates and can be methylated by catechol O-methyltransferase using S-adenosylmethionine as the methyl donor to form 3-O-methyldopa (3-OMD). 3-OMD is more stable than L-dopa and can be detected in blood.


Limitations

This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.


Methodology

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


LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
620176 3-O-Methyldopa Plasma 50141-1 230163 Specimen Status N/A
620176 3-O-Methyldopa Plasma 50141-1 620177 Result 50141-1
620176 3-O-Methyldopa Plasma 50141-1 620178 Interpretation N/A

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The LOINC® codes are copyright © 1994-2018, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf