Phenytoin

Department

Core Biochemistry

Delphic Registration Code

PHTN

Synonyms

Dilantin
diphenylhydantoin

Turnaround Time

3 hours

Test Code

4760

Specimen Type

• Serum
• Plasma

Specimen Requirements

Tube/Container Type:

Preferred

• Lithium Heparin - Non-gel (Green Cap)

Acceptable

• Serum (Red Cap)
• SST II (Gold Cap)
• Lithium Heparin - Gel (Green Cap)

Preferred Sample Volume (ml)

4.5

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• Lithium Heparin - Non-gel (Green Cap)

Minimum Sample Volume (ml)

0.6

Additional Specimen Information

Specimen should be collected immediately pre-dose.

Aliquot Instructions

Sample Type

• Serum
• Plasma

Minimum Volume (ml)

0.2

Transport to Lab

Ambient (8 - 24 degrees Celsius)
If overnight - Chilled (2 - 8 degrees Celsius)

Interpretation

The standard half-life of phenytoin is 24 hours, with time to steady-state of 5 days.

Reference Intervals

Total phenytoin: 40 – 80 umol/L

Unbound (free) phenytoin: 4 – 9 umol/L

Test Method

Homogenous enzyme immunoassay performed on Beckman Coulter AU5822 analysers using Beckman Coulter reagents

Non-Funded Test Cost

$25.61 (Exclusive of GST)

Billing Code

4760

Contact Information

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