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Test Code GTOL or LAB27 Gentamicin Level, Serum or Plasma

Specimen Requirements

Container Type:

Optimal: Gold or Mint*

*For STAT requests

Acceptable: Red or Green
Optimal Collection Volume: 

4.5mL; full tube
Minimum Volume:

1 mL whole blood
Collection Instructions:

Gently invert the sample 5-6 times after collection.
Specimen Transport:

Refrigerate
Processing Instructions: 

1. If serum, allow the specimen to clot for 30 minutes.

2. Centrifuge specimen within 2 hours of collection.

3. After centrifugation, specimen tubes without a gel barrier should have the serum or plasma aliquoted to a false bottom container.

4. Keep the serum or plasma refrigerated until testing can be performed.

Specimen Stability

Specimen Type Temperature Time
Serum* Refrigerated 7 days
Frozen 4 weeks

*Note: Heparinized plasma in gel separator tubes is less stable than serum and is only suitable for add-on testing up to 2 days following sample collection.

Specimen Rejection Criteria

Hemolysis Mild OK; Moderate OK; Gross Reject
Lipemia Milk OK; Moderate OK; Gross Reject
Icterus Mild OK; Moderate OK; Gross Reject
Other Quantity not sufficient

Useful For

Monitoring peak and trough levels of gentamicin.

Methodology

Roche Cobas - Homogeneous enzyme immunoassay

Reference Ranges

The therapeutic range of gentamicin should be measured at peak and trough concentrations.

  • Equivalent diagnostic technologies have shown that in most adults, a peak therapeutic response is achieved with concentrations between 6 and 10 ug/mL.
  • Trough levels should be between 0.5 and 2.0 ug/mL.

Interpretive

Peak: GENPA - Clinical & Interpretive: Gentamicin, Peak, Serum (mayocliniclabs.com)

 

Trough: GENTA - Clinical & Interpretive: Gentamicin, Trough, Serum (mayocliniclabs.com)

Day(s) Performed

24/7

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Chemistry - Kalamazoo

Sample Retention Time

7 days

CPT Code

80170

LOINC Code

35668-3