Measurement of thiocyanate levels is used to monitor patients who are receiving continuous infusions of nitroprusside (Nipride), a vasodilator used in the ICU setting. Nitroprusside is metabolized to cyanide and thiocyanate. Published literature indicates that thiocyanate toxicity is very rare unless patients are given nitroprusside at high dose for an extended duration of time. A detailed analysis of UIHC patients (pediatric and adult) over the last 18 months found no instances of thiocyanate concentrations near the toxic range of 10 mg/dL. After discussion with adult and pediatric ICU physicians, it was decided that there was no longer justification to maintain thiocyanate as an in-house assay.

While there are no published consensus guidelines on when to obtain thiocyanate levels, thiocyanate levels should be considered for patients receiving > 2 mcg/Kg/min nitroprusside for > 48 hrs. Obtaining thiocyanate levels daily as a routine practice for every patient receiving nitroprusside is not justified by the published literature or the experience at UIHC. Checking thiocyanate levels twice weekly may be prudent for patients with renal failure who receive nitroprusside for > 48 hrs.

On October 8, 2009, thiocyanate levels will be mailed to a referral laboratory. The specimen requirements will change to:

Adult:  5 mLs whole blood in green top (sodium heparin) tube
Peds:  2 mLs whole blood in green top (sodium heparin) tube

Questions can be directed to Matthew Krasowski M.D., Ph.D. (Medical Director, Clinical Chemistry Laboratory) at 384-9380.