acetaminophen in serum/plasma

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Indications

Reference interval

  • Male & Female: 10-200 ug/mL

Principle

The unique reagents in this methodology are the matched lots of acetaminophen antibody & acetaminophen-glucose-6-phosphate dehydrogenase conjugate. The reaction sequence, in two steps, is as shown:

               ACTM                Ab-ACTM
  • Ab + + -------> + + ACTM-G6PD
            ACTM-G6PD           Ab-ACTM-G6PD         (active)
                                 (inhibited)
   Glucose-6-phosphate    ACTM-G6PD      6-Phosphogluconolactone
  • + ---------------> +
         NAD+              (active)      NADH(absorbs at 340 nm)
Where:   Ab = Acetaminophen Antibody
       ACTM = Acetaminophen
 ACTM-G6PD = Acetaminophen-glucose-6-phosphate  dehydrogenase conjugate

The concentration of acetaminophen determines the amount of acetaminophen-glucose-6-phosphate dehydrogenase conjugate (ACTM- G6PD) that is bound to the anti-acetaminophen antibody. The unbound conjugate catalyzes the oxidation of glucose-6-phosphate with the simultaneous reduction of NAD+ to NADH more rapidly than does the bound conjugate. The rate of increasing absorbance at 340 nm due to the increase in NADH is related to acetaminophen concentration by means of a mathematical function

Clinical significance

Acetaminophen is a widely used analgesic that is available without prescription & is frequently recommended when aspirin may present problems to a patient, particularly in pediatrics or after surgery. It can produce liver toxicity when taken in overdose due to the conversion to a toxic metabolite. Normally, the metabolite is conjugated with glutathione & excreted. Analysis not only confirms a suspected overdosage but, by additional analysis of times specimens, can offer a means of estimating the half-life of the drug. A lengthened half-life of the drug indicates that liver toxicity may occur.

Specimen

Patient Preparation: No special patient preparation is required.

Minimum sample size required is .5 milliliter: with an optimum size of 1.0 milliliters or larger.

More general terms

More specific terms

Additional terms

References

  1. Kaplan, L., & Pesce, A., Clinical Chemistry:theory, analysis, & correlation, C. V. Mosby Co., St. Louis, MO., 1984, pp. 1330.
  2. Tietz, N., Fundamentals of Clinical Chemistry, 3rd edition W. B. Saunders Co., Philadelphia, 1987, pp. 899.
  3. Tietz, N., Textbook of Clinical Chemistry, W. B. Saunders Co., Philadelphia, 1986, pp. 1731-1732.
  4. ACA IV Discrete Clinical Analyzer Instrument Manual, Volume 1:Operation, DuPont Company, Wilmington, Delaware, 1984.
  5. ACA IV Discrete Clinical Analyzer Instrument Manual, Volume 3:Chemistry, DuPont Company, Wilmington, Delaware, 1984.
  6. Package Insert, DuPont ACTM Calibrators, DuPont Company, Medical Products, Wilmington, Delaware, 1989.
  7. Acetaminophen Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0090001.jsp