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|Test Update Information||Acetaminophen assay changed from the Abbott Axsym method to the Beckman DxC method on 6/25/2012.|
|Performed by||Parnassus Chemistry|
|In House Availability||Test available 24 hours per day 7 days per week|
|Method||Turbidimetric inhibition immunoassay (Beckman DxC800)|
|Container type||Gold top or Light Green top|
|Amount to Collect||1 mL blood|
|Preferred volume||0.5 mL serum|
|Min. Volume||0.2 mL serum|
|Critical value||> 50 mg/L|
|Stability||Room temperature 8 hours, refrigerated 2 days, frozen 1 week|
|Turn around times||STAT 1 hour, Routine 1-3 days|
|Additional information||In suspected intoxication, at least 4 hours must have elapsed post-ingestion before a serum level can assist in determining the need to initiate N-acetylcysteine therapy; earlier levels are uninterpretable for this purpose. For additional emergency information, you may call the San Francisco regional poison center, 1-800-876-4766 (from UCSF dial 47-28600)
Note: some monoclonal proteins may cause falsely low acetaminophen results. The presence of human anti-mouse antibodies or heterophile antibodies may also interfere with the acetaminophen assay in some cases. Testing for acetaminophen levels in parallel dilution studies and with a different assay may be useful in cases where interference by a monoclonal protein or abnormal immunoglobulin is suspected.
|Last Updated||6/20/2012 1:50:19 PM|
|Image caption||Nomogram: acetaminophen plasma concentration vs. time after acetaminophen ingestion (adapted from Rumack BH, Matthew H. Acetaminophen poisoning and toxicity. Pediatrics. 1975;55;871-876, with permission). The nomogram has been developed to estimate the probability of whether a plasma acetaminophen concentration in relation to the interval post ingestion will result in hepatotoxicity and, therefore, whether N-acetylcysteine therapy should be administered.
CAUTIONS FOR USE OF THIS CHART:
Time coordinates refer to time post ingestion. Graph relates only to plasma concentrations following a single, acute overdose ingestion. The Treatment Line is plotted 25% below the Rumack-Matthew Line to allow for potential errors in plasma acetaminophen assays and estimated time from ingestion of an overdose.