Specimen Requirements

Collection Instructions:

1. Serum and Plasma gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.

Submit only 1 of the following specimens:

Preferred:

Serum

Draw blood in a gold-top serum gel tube(s). Spin down and send 1 mL of serum refrigerated.    Specimen is usually drawn just prior to next oral dose. 

Note:

1.A speckled-top serum gel tube (s) or a plain, red-top tube(s) is also acceptable.

2. Two weeks of therapy may be necessary to achieve steady-state.

3. Coadministration of barbiturates, benzodiazepines, phenytoin, succinimides, or valproic acid may induce lower serum levels but better seizure control. Patients may become toxic at lower levels. Carbamazepine may decrease levels of phenytoin and warfarin.
4. Date and time of draw is required on request form and specimen for processing.

5. Indicate serum on request form.

6. Label specimen appropriately (serum).

Alternate: Preferred for VWH Lab

Plasma

Draw blood in a green-top (heparin) tube(s). Spin down and send 1 mL of heparinized plasma refrigerated. Specimen is usually drawn just prior to next oral dose. 

Note: 

1. Two weeks of therapy may be necessary to achieve steady-state.

2. Coadministration of barbiturates, benzodiazepines, phenytoin, succinimides, or valproic acid may induce lower serum levels but better seizure control. Patients may become toxic at lower levels. Carbamazepine may decrease levels of phenytoin and warfarin.

3. Date and time of draw is required on request form and specimen for processing.

4. Indicate plasma on request form.

5. Label specimen appropriately (plasma).

VWH Lab: 

6. Tubes of blood are to be kept closed at all times and in a vertical position. It is recommended that the serum or plasma be physically separated from contact with cells within two hours from the time of collection.

7. Separated serum or plasma should not remain at room temperature longer than 8 hours. If assays are not completed within 8 hours, serum or plasma should be stored at +2°C to +8°C for up to 48 hrs. 

Roche Specimen Stability Information