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


Plasma, frozen


1.0 mL

Minimum Volume

0.5 mL


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


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



Room temperature






Causes for Rejection

Thawed sample

Test Details


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.


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


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


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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