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Aminoglycosides Blood Test

Last updated May 31, 2018

Approved by: Maulik P. Purohit MD, MPH

The Aminoglycosides Blood Test determines the levels of aminoglycosides in blood. It is used to ensure that aminoglycoside levels stay within a safe yet effective range.

What are other Names for this Test? (Equivalent Terms)

  • Amikacin Blood Test
  • Gentamicin Blood Test
  • Tobramycin Blood Test

What is Aminoglycosides Blood Test? (Background Information)

  • An aminoglycoside is an antibiotic that targets bacteria. It prevents bacteria from making proteins, which is essential for their survival. The commonly prescribed aminoglycosides include gentamicin (Garamycin), amikacin (Amikin), and tobramycin (Nebcin).
  • Aminoglycosides work by binding to the molecular machines in bacteria that make proteins. This prevents the bacteria from growing, but does not necessarily kill them. Thus, gentamicin is a bacteriostatic
  • In contrast, antibiotics that bind to the cell wall, such as glycopeptides (like vancomycin), rapidly kill bacteria by causing them to swell and burst. The downside to killing the bacteria is that bacterial components may flood the body and cause a massive immune response, which can be fatal. Aminoglycosides do not cause widespread bacterial death, so they may be safer
  • However, bacteria that are especially resilient may simply wait out the bacteriostatic. When therapy is stopped, protein production once again resumes, and the bacteria may again cause disease
  • This is one of the reasons that aminoglycoside levels need to be carefully monitored and an effective dose needs to be maintained at all times
  • Aminoglycosides are not well absorbed by the intestinal walls. Thus, they need to be given through injection. Aminoglycoside levels peak between ½ and 1½ hours after injection. The half-life for aminoglycosides is about 2 hours, which means they remain detectable in blood for around 4 hours. Aminoglycosides are then removed via urine
  • Aminoglycosides circulate for longer periods in individuals with damaged kidneys. In these individuals, the half-life for aminoglycosides may be as high as 1 to 4 days
  • The Aminoglycosides Blood Test determines the levels of aminoglycosides in blood. It is used to ensure that aminoglycoside levels stay within a safe yet effective range

What are the Clinical indications for performing the Aminoglycosides Blood Test?

The clinical indications for performing the Aminoglycosides Blood Test include monitoring aminoglycosides antibiotic therapy.

How is the Specimen Collected for Aminoglycosides Blood Test?

Following is the specimen collection process for Aminoglycosides Blood Test:

Sample required: Blood

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Aminoglycosides Blood Test Result?

The significance of the Aminoglycosides Blood Test result is explained:

  • A high Aminoglycosides Blood Test value may indicate aminoglycoside toxicity, which is marked by:
    • Lower back pain
    • Discolored urine
    • Frequent urination
    • Painful urination
    • Fatigue
    • Nausea
    • Vomiting
    • Diarrhea 
  • A low Aminoglycosides Blood Test value may indicate that more aminoglycoside is necessary to achieve a therapeutic dose

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Antibiotics, such as aminoglycosides, disrupt the natural bacterial balance in the intestines. This may contribute to digestive side effects. Ironically, it may also cause bacterial infections, such as those by C. difficile. Probiotics and other therapies may be used to repopulate the gut with healthy bacteria in such cases

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

The following DoveMed website link is a useful resource for additional information:


Please visit our Laboratory Procedures Center for more physician-approved health information:


References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Oct. 30, 2015
Last updated: May 31, 2018