Generally effective therapeutic concentration:

10-30 mcg/mL

Toxic:

> 150 mcg/mL

If time of ingestion is unknown, samples taken 4 hours apart will give a better indication of whether toxicity exists. The concern in acetaminophen ingestion is whether:

     1. The blood concentration is increasing or decreasing

     2. The blood concentration is at a level which

         represents a threat of irreversible liver damage

     3. The potentially toxic antidote should be given.