Laboratory Medicine Program

Thiocyanate

Clinical Decription:
Nitroprusside relaxes both arteriolar and venous smooth muscle, decreasing preload and afterload. By reducing preload, myocardial workload is decreased and the risk of ischemic changes including angina are reduced. The toxicity of nitroprusside is derived from the reaction of the ferrous ion in the nitroprusside with sulfhydryl-containing compounds in the red blood cell. Cyanide is produced and then subsequently reduced to thiocyanate in the liver. Thiocyanate is excreted in the urine with a half-life (t1/2) of 3-4 days. After prolonged administration thiocyanate may accumulate, causing nausea, vomiting, sweating, palpitations and acute toxic psychosis. Toxicity occurs at plasma concentrations > 1.7 mmol/L. Excessive concentrations may also interfere with thyroid function. Plasma thiocyanate levels should be monitored closely on patients with renal impairment.
<br/><em>Bowler RG. Determination of thiocyanate in blood serum. J. Biochem, 1944; 38:388</em>

Method: Spectrophotometry; Agilent

Component Tests Used: n/a

Reference Ranges Used:
< or = 1.7 mmol/L

Specimen Type: serum
Volume: 3 mL (minimum: 1 mL)

Shipping: 4C

Special Instructions: Optimum sampling time: samples should not be taken until after 48 h of I.V. therapy with nitroprusside has been completed in high-risk patients. Centrifuge and aliquot sample.

Testing Schedule(s): Monday through Friday 0900-1500 hrs.

Turnaround Time: As requested

For more information, call 416.340.5227 or 1.866.865.5227