Gentamicin, Single Daily Dose

Abbrev Code:GENTSD   
Order Code:LAB4569Order Name:Gentamicin Single Dose
Methodology:Turbidimetric rate
CPT Codes: 80170 x1
Turnaround Time:Performed and reported 24 hours/day
Special Instructions:Order when single daily dose is given. Comment last dose information on request form.

Collection Instructions

Optimal Volume:2.5 mL
Minimum\Peds Volume:0.6 mL, 0.4 pediatric patients only.
Container:Red (no gel), St Johns/St Joseph/Woodwinds-Green (lithium heparin, no gel)
Alternate Containers: Green (lithium heparin, no gel), St Johns/St Joseph/Woodwinds - Red (no gel)
Collection Instructions:Trough levels: Collect immediately prior to the next dose. Peak levels: Collect 60 minutes after the end of IV infusion; 1-2 hours if decreased renal function.
Causes for Rejection:Processed >2 hours after collection and patient is receiving beta-lactam antibiotics structurally similar to gentamicin (e.g. netilmicin, sagamicin and sisomicin) or cephalosporin; collection in a gel tube

Processing and Shipping

Specimen Processing:Centrifuge and assay immediately. If assaying is delayed more than 2 hours, then aliquot 1.25 mL, 0.2 mL minimum (adult) 0.1 mL minimum (peds) and freeze the sample.
Shipping Instructions:Ship on dry ice.
Stability:If specimen is received >2 hrs after collection, check with PCU/Clinic to see if patient is receiving beta-lactam antibiotics or cephalosporins. If so, cancel the test. Beta-lactam antibiotics and cephalosporins will inactivate aminoglycosides causing falsely low results.
Test Performed at or Referral Lab Chemistry  (UMMC-East Bank, Lakes, Northland, Southdale, UMMC/UMMCH-West Bank)


Critical Range:Greater than 35 mg/L for single daily dosing.
Therapeutic Range:Trough: Approaching zero. Peak: 17-24 mg/L
Use:Monitor therapeutic dosing and evaluate toxicity. Half-life is 1.5-3 h (adult: less than 30 y); 3-6 h (adult: 30 y or greater); 4-8 h (neonate).

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