Laboratory Medicine

Test catalogue

Gentamicin
Test Name Gentamicin (Pre-Dose, Post-Dose, Random)
Specimen Type / Requirements Container Type = 1 Red Top Minimum Testing Volume = 0.5 mL serum Tube must fill to at least ½ or greater of its vacuum capacity
Specimen Handling Collection Instructions: Serum collected in red top tube. Avoid gold top (SST). For pre-dose measurement, collect immediately before next dose. Wait until the 3rd dose before collecting samples for therapeutic monitoring. For traditional dosing (post-dose), collect sample 30 minutes after end of dose infusion. Wait until the 3rd dose before collecting samples for therapeutic monitoring. For extended dosing (post-dose), after the 3rd dose collect a sample 8-12 hours after end of dose infusion. Record the exact time of sample and use nomogram for dosage adjustment if necessary. For further assistance with interpretation contact unit pharmacist. Write your initials, date and time of collection on the collection label or requisition. Special Instructions Serum free from hemolysis collected without gel separator. Separate samples from cells as soon as possible. Repeated freezing and thawing of samples should be avoided Rejection Criteria: Gel separator, Unlabeled or Not Sufficient Quantity samples will be rejected. Stability: Stable at room temperature for 3 days, refrigerated for 6 weeks, frozen for 6 months (avoid repeat freeze/thaw cycles). Transportation: Send sample to core lab as soon as possible.
Required Documentation
Turnaround Time STAT: 1 hour Routine: 4 hours	Test Utilization N/A
Reference Value For traditional ("conventional") dosing method: Pre-dose: < 2.0 mg/L for adults and pediatrics ½ hour post-dose: 4.0 - 10.0 mg/L (pediatrics 5.0 - 10.0 mg/L) When used for synergy in the treatment of gram positive endocarditis in adults: Pre-dose: < 1.0 mg/L ½ hour post-dose: 3.0 - 4.0 mg/L For extended interval (“once daily”) dosing method. Pre-dose: < 1.0 mg/L for adults 8 - 12 hours post-dose for adults: use nomogram for interpretation; 3 and 6 hours post-dose for pediatrics: use nomogram for interpretation. Critical Values Pre-dose: >2.0 mg/L ½ hour post-dose: >10.0 mg/L
Test Code LAB26, LAB27, LAB28	Methodology Enzyme Immunoassay
Testing Location SMH-Biochemistry	Other Information Last Updated: June 22, 2026

Gentamicin

Test Name

Gentamicin (Pre-Dose, Post-Dose, Random)

Specimen Type / Requirements

Container Type = 1 Red Top

Minimum Testing Volume = 0.5 mL serum

Tube must fill to at least ½ or greater of its vacuum capacity

Specimen Handling

Collection Instructions: Serum collected in red top tube. Avoid gold top (SST).

For pre-dose measurement, collect immediately before next dose. Wait until the 3rd dose before collecting samples for therapeutic monitoring.

For traditional dosing (post-dose), collect sample 30 minutes after end of dose infusion. Wait until the 3rd dose before collecting samples for therapeutic monitoring.

For extended dosing (post-dose), after the 3rd dose collect a sample 8-12 hours after end of dose infusion. Record the exact time of sample and use nomogram for dosage adjustment if necessary.

For further assistance with interpretation contact unit pharmacist.

Write your initials, date and time of collection on the collection label or requisition.

Special Instructions Serum free from hemolysis collected without gel separator. Separate samples from cells as soon as possible. Repeated freezing and thawing of samples should be avoided

Rejection Criteria: Gel separator, Unlabeled or Not Sufficient Quantity samples will be rejected.

Stability: Stable at room temperature for 3 days, refrigerated for 6 weeks, frozen for 6 months (avoid repeat freeze/thaw cycles).

Transportation: Send sample to core lab as soon as possible.

Required Documentation

Turnaround Time

STAT: 1 hour

Routine: 4 hours

Test Utilization

N/A

Reference Value

For traditional ("conventional") dosing method:

Pre-dose: < 2.0 mg/L for adults and pediatrics

½ hour post-dose: 4.0 - 10.0 mg/L (pediatrics 5.0 - 10.0 mg/L)

When used for synergy in the treatment of gram positive endocarditis in adults:

Pre-dose: < 1.0 mg/L

½ hour post-dose: 3.0 - 4.0 mg/L

For extended interval (“once daily”) dosing method.

Pre-dose: < 1.0 mg/L for adults

8 - 12 hours post-dose for adults: use nomogram for interpretation;

3 and 6 hours post-dose for pediatrics: use nomogram for interpretation.

Critical Values

Pre-dose: >2.0 mg/L

½ hour post-dose: >10.0 mg/L

Test Code

LAB26, LAB27, LAB28

Methodology

Enzyme Immunoassay

Testing Location

SMH-Biochemistry

Other Information

Last Updated: June 22, 2026