Lab Test

Procainamide Level (including NAPA)

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

Test Codes

ARUP # 90151, EPIC: LAB6833, SOFT: XPRNA

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tube.
Also acceptable: One Dark Green-top Sodium Heparin tube.

Do not use Serum Separator Tubes.
Time of Collection: Trough, just prior to the next dose.
Record the exact time of specimen collection on the tube or in the computer system.

Physician Office/Draw Specimen Preparation

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

Preparation for Courier Transport

Transport: 1.0 mL serum or plasma, refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL)

Rejection Criteria

Serum Separator (SST) tubes.

Specimens not collected and processed as indicated.

In-Lab Processing

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

Transport: 1.0 mL serum or plasma, refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL) 

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 7 days
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 6 months

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 ARUP Laboratories, Salt Lake City, UT.

Performed

Sunday – Saturday.
Results available in 2-4 days.

Reference Range

Procainamide Therapeutic Range: 4-10 mcg/mL.
Procainamide Critical Range: Greater than 12 mcg/mL.
N-Acetylprocainamide Therapeutic Range: 6-20mcg/mL.
N-Acetylprocainamide Critical Range: Greater than 35 mcg/mL.

Test Methodology

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

Contacts

Last Updated

4/1/2020

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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.