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Blood concentrations may indicate tolerance in normally functioning individuals being prescribed high-dose medications

In the case of tolerant pain patients, routine blood testing to determine steady-state blood ranges may provide crucial information in the event of a patient’s unexpected death. Tolerant pain patients are often able to function with opioid blood concentrations well above what is considered “therapeutic,” “toxic” or even “lethal” in naïve, non-tolerant patients. To compare therapeutic and toxic blood levels, see the chart^1-4 below.

* Transdermal fentanyl produces concentrations of 1-3 ng/mL. Concentrations significantly higher than this range suggest oral or parenteral administration.
 
Unfortunately, the issue of tolerance may not always be considered in postmortem investigations, and elevated concentrations of opioids in postmortem specimens can be misleading when evaluating the cause of death. Periodic blood draws on all opioid patients for the purpose of documenting tolerance could help to protect physicians from possible investigation in the unfortunate event of a patient’s death.

Click here to read our article on the benefits of blood testing in Practical Pain Management. 

Click here to learn more about our DetectiMed® Panel for blood testing. 

References 

1. Baselt RC. Disposition of Toxic Drugs and Chemicals in Man, 5th Ed. Chemical Toxicology Institute. Foster City, California, 2000.
2. Goldman L and Ausiiells D. Reference Intervals and Laboratory Values in Cecil Textbook of Medicine, 22nd Ed. Eds, Saunders, Philadelphia, 2004.
3. Tennant F. Tennant Blood Study: Preliminary Report. Pract Pain Manage, 2005.
4. Data on file at AIT Laboratories for results recorded between 6/1/2008 and 6/1/2010.