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Test Code QUIN Quinidine, Serum


Specimen Required


Collection Container/Tube: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Red-top tubes should be centrifuged and the serum aliquoted into a plastic vial within 2 hours of collection.


Useful For

Assessing and adjusting quinidine dosage for optimal therapeutic level

 

Assessing quinidine toxicity

Method Name

Kinetic Interaction of Microparticles in Solution (KIMS)

Reporting Name

Quinidine, S

Specimen Type

Serum Red

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Refrigerated (preferred) 14 days
  Frozen  28 days
  Ambient  14 days

Reject Due To

Gross hemolysis Reject

Clinical Information

Quinidine is indicated for atrial fibrillation and flutter, and life-threatening ventricular arrhythmia. Optimal serum concentrations are in the range of 2.0 to 5.0 mcg/mL, with toxicity apparent at levels of 6.0 mcg/mL or higher. Symptoms of toxicity (cinchonism) include tinnitus, light-headedness, premature ventricular contractions, and atrioventricular block. Gastrointestinal distress is a frequent side effect, which becomes more severe and is associated with nausea and vomiting at higher drug concentrations.

 

The half-life of quinidine is 6 to 8 hours, and the drug lacks any significant active metabolites. Physiologic processes that generally reduce hepatic metabolism and renal clearance increase serum quinidine levels, while comedication with cytochrome p450 (CYP)-enzyme inducers enhances clearance and results in lower blood concentrations.

Reference Values

Therapeutic: 2.0-5.0 mcg/mL

Critical value: ≥6.0 mcg/mL

Interpretation

Optimal response to quinidine occurs when the serum level is between 2.0 to 5.0 mcg/mL.

Cautions

No significant cautionary statements

Method Description

Kinetic interaction of microparticles in solution (KIMS) as measured by changes in light transmission. The assay is a homogeneous immunoassay based on the principle of measuring changes in scattered light or absorbance which result when activated microparticles aggregate. The microparticles are coated with quinidine and rapidly aggregate in the presence of a quinidine antibody solution. When a sample containing quinidine is introduced, the aggregation reaction is partially inhibited, slowing the rate of the aggregation process. Antibody bound to sample drug is no longer available to promote microparticle aggregation, and subsequent particle lattice formation is inhibited. Thus, a classic inhibition curve with respect to quinidine concentration is obtained, with the maximum rate of aggregation at the lowest quinidine concentration. By monitoring the change in scattered light or absorbance, a concentration-dependent curve is obtained.(Package insert: Roche Quinidine reagent, Roche Diagnostic Corp, Indianapolis, IN; 08/2015)

Day(s) and Time(s) Performed

Monday through Saturday

Analytic Time

Same day/1 day

Specimen Retention Time

2 weeks

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

80194

LOINC Code Information

Test ID Test Order Name Order LOINC Value
QUIN Quinidine, S 6694-4

 

Result ID Test Result Name Result LOINC Value
8302 Quinidine, S 6694-4

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.