Monitor therapeutic drug level.
5 - 20 mcg/mL; Toxic > 25 mcg/mL
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Collect specimen in a red, green (heparin), or lavender (EDTA) top tube; do not use SST tube. Centrifuge, aliquot serum or plasma into a plastic vial and refrigerate.