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Procainamide Level (including NAPA)

Pronestyl, Acecainide, NAPA, Procainamide and N-Acetylprocainamide (NAPA)

Test Codes

EPIC: LAB6833, Beaker: XPRNA, Mayo: PA

Department

Send Outs

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tube.
Also acceptable: One gold-top Serum Separator (SST) tube.

Physician Office/Draw Specimen Preparation

Centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: 0.5 mL serum, refrigerated (2-8°C or 36-46°F). (Minimum: 0.25 mL)

Rejection Criteria

Specimens not collected and processed as indicated.

In-Lab Processing

Centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Transport: 0.5 mL serum, refrigerated (2-8°C or 36-46°F). (Minimum: 0.25 mL) 

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 14 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Mayo Clinic Laboratories in Rochester, MN.

Performed

Monday – Saturday.
Results available in 2-3 days.

Reference Range

By report.

Test Methodology

Homogeneous Enzyme Immunoassay.

Interpretation

The Procainamide/NAPA ratio is determined by the patient's acetylator phenotype. Fast acetylators tend to have NAPA levels twice that of Procainamide and are thought to have a lower risk of drug-induced lupus erythematosus syndrome. Slow acetylators have Procainamide levels greater than NAPA. Because NAPA is eliminated to a greater extent renally than Procainamide, the presence of renal disease will make the determination of acetylator phenotype more difficult. Approximately 50% of the population are fast acetylators and the remainder are slow acetylators.

Clinical Utility

This assay is used to monitor the therapeutic drug level and evaluate the toxicity of procainamide. Procainamide is an antiarrhythmic drug. It has a narrow therapeutic index and can produce serious side effects. The major active metabolite of procainamide is N-acetylprocainamide (NAPA). Usually its concentration is comparable to or greater than that of procainamide. It has been suggested that the concentrations of procainamide and NAPA should be monitored simultaneously in order to optimize therapy.

CPT Codes

80192
LOINC:  3834-9, 3982-6,3983-4

Contacts

Last Updated

9/18/2023