Most phenytoin in the blood is bound to albumin, with only the small free fraction biologically active. In patients with low albumin, kidney disease, or those taking interacting drugs, total phenytoin can be misleading — free phenytoin gives a more accurate picture of drug exposure.
This test is used in patients with hypoalbuminemia, end-stage renal disease, critical illness, and complex drug regimens where total phenytoin doesn't reliably reflect activity. Sample type is serum.
We are CLIA certified, the highest level of Medical industry compliance and standards.
Book an appointment