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Test Code GENTP Gentamicin Level Peak, LAB28


Turbidimetric Inhibition Immunoassay

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements



Preferred:  Mint green-top (lithium heparin) tube

Acceptable:  Green-top tube, gold-top serum gel tube or plain, red-top tube

Specimen Volume: 0.1 mL serum or plasma

Stability:  Samples should be physically separated from cells as soon as possible with a maximum limit of 2 hours from the time of collection.  Separated specimens stored at 2 – 8°C and analyzed within 72 hours

Collection Instructions: Peak level should be drawn 1 hour post dose (intramuscular) or 30 to 60 minutes post dose (intravenous).  Specimens should not be drawn or stored in glass.

Note: Gentamicin time to steady state is after 2.5 to 75 hours of chronic dosing.


Reference Values

Therapeutic range: 5-10 mcg/mL

Critical value: >12 mcg/mL

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding


Useful For

Gentamicin is an aminoglycoside antibiotic which exhibits high potency and a broad spectrum bacterial action against both gram-negative and gram-positive organisms.  It exhibits a narrow therapeutic index which makes its use hazardous, especially in patients with impaired renal function.