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acetaminophen in serum/plasma

Indications: - evaluation of acetaminophen toxicity Reference values: - Male & Female: 10-200 ug/mL 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. 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 1) Ab + + -------> + + ACTM-G6PD ACTM-G6PD Ab-ACTM-G6PD (active) (inhibited) Glucose-6-phosphate ACTM-G6PD 6-Phosphogluconolactone 2) + ---------------> + 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. Specimen: Patient Preparation: No special patient preparation is required. 1) Serum is the specimen of choice. Specimens are collected by venipuncture in a red top vacutainer. Specimen is stable for at least one week at room temperature & 1 year if frozen at -20C. 2) Plasma samples are also acceptable. These samples are collected by venipuncture in a green top tube. Hemolysis, icterus, & lipemia do not interfere with the ACTM method. Minimum sample size required is .5 milliliter: with an optimum size of 1.0 milliliters or larger.

Related

acetaminophen (Tylenol, Paracematol, Panadol, Tempra, Datril, APAP, non-Aspirin) acetaminophen poisoning

Specific

acetaminophen free in serum/plasma acetaminophen+codeine in serum/plasma acetaminophen+oxycodone in serum/plasma

General

acetaminophen in body fluid therapeutic drug measurement

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: 90001