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Drugs interfere with blood gas sodium results

17 Dec 2023

Perhexiline maleate, atomoxetine hydrochloride may falsely elevate results

By: Amanda Jacobson, senior laboratory specialist, chemistry, and Andrew Judd, MD, laboratory medical director

Siemens Healthcare Diagnostics has determined that two drugs, perhexiline maleate and atomoxetine hydrochloride, may interfere with sodium results reported on the RAPIDPoint blood gas analyzers, which are used in the Salem Health operating room, Salem Health Laboratory – Building A and Salem Health Laboratory – Dallas.

Here’s the effect these drugs had on samples:


Concentration Tested (mg/dL)

Level of Interference on Sodium (mmol/L)

Perhexiline maleate



Atomoxetine hydrochloride



Please note that perhexiline maleate is not an approved drug in the United States. Siemens Healthcare is aware of two complaints associated with this issue. The complaints are from non-U.S. customers.  There have been no reports of adverse events.

What does this mean for providers?

The presence of perhexiline maleate and atomoxetine hydrochloride may cause erroneously elevated sodium results. This may lead to unrecognized hyponatremia and/or the inappropriate treatment of hypernatremia.

Mitigations include:

  • The geographically restricted use of perhexiline maleate (which is mostly used in Australia and New Zealand).
  • The short time interval testing needed after dosing atomoxetine hydrochloride, due to its short half-life.
  • Correlation of results with other electrolyte results, such as chloride.
  • Historical sodium results.
  • The clinical history of the patient.


Siemens Healthineers Urgent Medical Device Correction POC 23-018.A.US Sept. 2023.


Call Amanda Jacobson, senior laboratory specialist, chemistry, at 503-561-5113 or Andrew Judd, MD, laboratory medical director, at 503-814-1632.