Test Code GENT Gentamicin Levels

Important Note

High concentrations of penicillins or cephalosporins have been shown to inactivate Gentamicin (an aminoglycoside) in vitro. Therefore, these specimens should be placed immediately on ice after collection and run within ½ hour of collection or the plasma removed from the cells and frozen until analysis. If a specimen is received that has not been on ice, call the Pharmacy or physician to see if the patient has been taking penicillin or a cephalosporin, if not, the Gentamicin may be run as soon as possible.

Additional Codes

Cerner	NextGen
Gentamicin Level Random	Gentamicin Level Random
Gentamicin Level Trough	Gentamicin Level Trough
Gentamicin Level Post Dose	Gentamicin Level Post Dose
Gentamicin Level 12 Hr Post Dose	Gentamicin Level 12 Hr Post Dose

Alternate Name(s)

Gentamicin Level Random

Gentamicin Level Trough

Gentamicin Level Post Dose

Gentamicin Level 12 Hr Post Dose

Useful For

Gentamicin is used in the treatment of serious infections caused by susceptible strains of gram-negative microorganisms and particular gram-positive organisms that are resistant to less toxic antibiotics. Gentamicin is safe and effective only in a narrow range of concentrations for a given indication. Exposure to high gentamicin concentrations for a prolonged period may cause renal impairment or ototoxicity. Serum or plasma gentamicin measurements are used in the diagnosis and treatment of gentamicin overdose and in monitoring levels of gentamicin to ensure appropriate therapy.

Methodology

Enzymatic Homogenous CIA, Two-point rate

Patient Preparation

None

Collection Instructions

Standard phlebotomy practices.
High concentrations of penicillins or cephalosporins have been shown to inactivate Gentamicin (an aminoglycoside) in vitro. Therefore, these specimens should be placed immediately on ice after collection and run within ½ hour of collection or the plasma removed from the cells and frozen until analysis.

Specimen Requirements

Container

Specimen Type	Tube
Lithium Heparin Plasma
Serum	or
SST Up to 24 hours	or or

Stability

Storage	Temperature	Stability
Room Temperature	18-28°C	≤ 2 hours If separated within 1 hour
Refrigerated	2-8°C	≤ 7 days If separated within 1 hour
Frozen	≤-18 °C	≤ 14 days If separated within 1 hour

Rejection Criteria

Gross Hemolysis

Result Reporting and Reference Values

Reported in µg/mL

	Therapeutic Range	Low Critical	High Critical
Trough	<2.0	N/A	>4.0
Random	<2.0	N/A	>10
Peak	4-10	<0.6	>10.5
12 hr	<2.0	N/A	>4

Reflex Testing