Specimen:

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

2 ml; light green top tube or one 0.4 ml microtubes.  (Sufficient for 
one or more anticonvulsant drugs).

Testing Schedule:

24 hrs/day, 7 days a week, including holidays.

Analytic Time:

3 hours (upon receipt in laboratory)

Reference Range:

15-40 mcg/ml

Critical value: >60 mcg/ml

Test
Limitations:

Criterion: recovery plus or minus 1.2 ug/ml of initial value at 
concentrations less than 12 ug/ml or plus or minus 10% of initial value 
at concentrations greater than 12 ug/ml.

Icterus: No significant interference up to an I index of 60 
(approximate bilirubin concentration: 60 mg/dl).

Hemolysis: No significant interference up to an H index of 1000 
(approximate hemoglobin concentration: 1000 mg/dl).

Lipemia (Intralipid): No significant interference up to an L index of 
1000 (approximate triglyceride concentration: 2000 mg/dl). There is 
poor correlation between turbidity and triglycerides concentration.

Total Protein: No significant interference up to a concentration of
12.8 g/dl.

Rheumatoid factor: No significant interference up to a concentration of 
180 IU/ml.

Mephobarbital (greater than 100%) and amobarbital (greater than 20%) 
show significant cross-reactivity.

As with any assay employing mouse antibodies, the possibility exists 
for interference by human anti-mouse antibodies (HAMA) in the sample, 
which could cause falsely elevated results.

The incidence of patients with antibodies to E. coli beta 
-galactosidase is extremely low. However, some samples containing such 
antibodies can result in artificially high phenobarbital results that 
do not fit the clinical profile.

Methodology:

EIA (Enzymatic ImmunoAssay)

CPT Code:

82205

See Additional Information:
Chemistry Critical Lab Values