Sign in →

Epic Test Code LAB27 Gentamicin, Random




Quantitative analysis for Gentamycin

Specimen Type

Serum or Plasma

Preferred Container

Gold or Red Top

Alternate Container

Green top

Volume Required

0.5 mL (Serum or Plasma)

Storage Requirements

Normal procedures for collecting and storing serum and plasma may be used for samples to be analyzed by this method.

Sample tubes should be centrifuged within 2 hours of collection followed by transfer of the serum (red or gold top) or plasma (green top) to a labeled plastic, aliquot tube.

Transportation Needs

Deliver specimens to the laboratory within 1 hour of collection.

Causes for Rejection

Mislabeled or unlabeled specimen

Hemolysis ≥ (1000 mg/dL HgB)

Lipemia ≥ (1300+- 75 mg/dL Trig)

Bilirubin ≥ (60 mg/dL Bili)

Serum > 3 days refrigerated

Plasma > 24 hours room temperature

Days of Analysis


Additional Information

Collection Guideline:

Obtain a baseline creatinine and repeat at 1-3 day intervals.
Begin monitoring after steady state is achieved (usually 3-4 doses).

Monitor at least one peak (60-90 min after IM or 30-60 min IV) and one trough (within 30 min of next dose).

Repeat trough measurements at 3-4 day intervals or sooner if warranted by clinical status.
Base frequency of monitoring on changes in dose and patient symptoms

Perform urinalysis by day 3 and repeat as necessary to assess early proximal tubular dysfunction.

Available STAT



Siemens Dimension

Reference Values

Level Units Therapeutic Range High Critical Value
Random ug/mL 2 - 8 >18
Peak ug/mL 4 - 8 > 18
Trough ug/mL < 2 > 2


Therapeutic gentamicin concentrations vary significantly depending on the individual patient. A range of 4.0-8.0 µg/mL [8.64-17.28 µmol/L] for peak drug levels indicates effective plasma or serum levels for many patients; however, some individuals are best treated at concentrations outside this range. Although it has not yet been established exactly what specimen concentration is toxic, minimal values in excess of 2 µg/mL [4.32 µmol/L] for longer than 10 days have been associated with toxicity.

CPT Code


Last Updated



Aminoglycosides structurally similar to gentamicin (e.g. netilmicin, sagamicin, and sisomicin) may significantly cross-react with this method. Therefore, GENT cannot reliably be used for patients receiving these antibiotics separately or in combination with gentamicin.

LIS Code


Minimum Volume

0.1 mL (Serum or Plasma)