Specimen Requirements

Preferred Collection Container: green top lithium heparin tube, SST 

Also Acceptable Collection Container: serum red top tube or EDTA purple top tube

Collection Information:

Patient should be on a constant dosage of phenytoin for at least 5 days before monitoring. Samples should be drawn just before the next dose. If toxicity is suspected, samples can be drawn at any time.

Collect 1 mL of Lithium heparinized plasma or serum.

Serum or plasma must be separated from cells within 2 hours of collection.