RT Journal Article
SR Electronic
T1 Interpretation of serum phenytoin concentrations in uremia is assay‐dependent
JF Neurology
JO Neurology
FD Lippincott Williams & Wilkins
SP 1250
OP 1250
DO 10.1212/WNL.34.9.1250
VO 34
IS 9
A1 Sirgo, Mark A.
A1 Green, Paul J.
A1 Rocci, Mario L.
A1 Vlasses, Peter H.
YR 1984
UL http://n.neurology.org/content/34/9/1250.abstract
AB A 25-year-old man with sickle cell disease and chronic renal insufficiency had tonic-clonic seizures treated with phenytoin. Serum phenytoin concentrations, total and free, measured by two homogenous enzyme immunoassays (EMIT®, ACA®) were reported to be within the therapeutic range, yet the patient experienced seizures. Values on discharge exceeded the therapeutic range but were not associated with signs or symptoms of toxicity. Reanalysis of serum samples by a more specific, high performance liquid chromatographic (HPLC) method revealed the previous values were spurious, apparently due to phenytoin metabolite cross-reactivity. Values by fluorescence polarization immunoassay (TDX®,) correlated well with those by HPLC, as well as with the patient's clinical course.