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Blood Test Tracker

Amikacin (Trough)

Shows how much of the antibiotic amikacin is still in your blood just before the next dose, a check that it is not building up.

AI-verified against cited sources. Awaiting expert reviewLOINC 3321-7

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What it is

Amikacin is an antibiotic given by injection or IV drip for serious infections, including some that resist other antibiotics. A trough level is drawn right before your next dose, when the drug is at its lowest. Your care team uses it together with the peak level to check that amikacin is clearing from your body and not building up.

Why it matters

If amikacin clears slowly, levels can stay high between doses. Long exposure raises the chance of kidney and inner-ear damage, and hearing damage can be permanent and may not cause warning symptoms during treatment. The trough is one of the main safety checks during treatment.

If it’s low

A very low or undetectable trough is common and often expected, especially with once-daily dosing, because the drug clears out before the next dose. It is usually a sign the drug is not building up.

Common causes

  • Once-daily or extended-interval dosing, which is designed to leave a drug-free gap
  • Normal or fast kidney clearance
  • A sample drawn later than the true trough point

What can help

  • Ask your care team whether the peak level and the overall plan are on target

If it’s high

A trough above about 10 mcg/mL is higher than the FDA label recommends. It can mean the drug is not clearing as fast as expected, often because the kidneys are working less well. Your team may adjust the dose or the time between doses.

Common causes

  • Reduced kidney function, including kidney strain from the infection or other medicines
  • Dehydration
  • Older age
  • A sample drawn too early, before the lowest point
  • Other medicines that stress the kidneys, such as strong water pills (loop diuretics) or other aminoglycosides

What can help

  • Tell your care team right away about new hearing loss, ringing in the ears, dizziness, numbness or much less urine
  • Ask whether your kidney function is being checked during treatment
  • Ask your care team whether staying well hydrated is right for you while you are on this medicine

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: up to 10 mcg/mL. Source: U.S. FDA label via NLM DailyMed (Hikma Pharmaceuticals), BMC Infectious Diseases, Journal of Pharmaceutical Health Care and Sciences.

What can affect your result

  • Kidney function, because amikacin leaves the body almost entirely through the kidneys
  • How long before the next dose the sample was drawn
  • Age, hydration and body weight
  • Dosing schedule: several smaller doses a day or one larger daily dose
  • Other medicines that can also stress the kidneys or ears
  • A sample drawn well after the dose is not a trough and will read higher than a true trough.
  • Drawing from the same line or arm that was used for the infusion can contaminate the sample and give a falsely high result.
  • Penicillin- and cephalosporin-type antibiotics can slowly inactivate amikacin in a collected blood sample that sits before testing, which can lower the measured result (FDA label). Labs handle such samples promptly, freeze them or treat them.

Just before the next dose, per the drug label. Troughs reflect how quickly the kidneys clear the drug between doses. They can climb within days if kidney function drops.

When to talk to a clinician

Tell your care team right away about new hearing loss, ringing in the ears, dizziness or loss of balance, numbness or tingling, muscle twitching, or a big drop in urine. Do not wait for the next scheduled blood draw.

Questions you could ask

  • When will the next trough be drawn, and when will you review the results with me?
  • What symptoms should I report right away while I am on this medicine?
  • Is my kidney function being checked during treatment?
  • Should my hearing or balance be checked?
  • Is the low trough expected with my dosing schedule?

Questions people ask

Why is my trough so low or undetectable?

With once-daily dosing, the drug is meant to clear almost completely before the next dose, which gives your kidneys and ears a rest. A very low trough is usually expected, not a sign the dose is too small.

What does a high trough mean?

It usually means amikacin is leaving your body more slowly than expected, often because the kidneys are working less well. Your team may then change the dose or the time between doses.

How do I convert mcg/mL to µmol/L?

Multiply mcg/mL (the same as mg/L) by 1.71. For example, 10 mcg/mL is about 17 µmol/L.

Show the science and sources

Units

  • 1 mcg/mL = 1 mcg/mL
  • 1 mcg/mL = 1 mg/L
  • 1 mcg/mL = 1.708 µmol/L

Open the Amikacin trough unit converter

For clinicians and researchers

The trough is the pre-dose concentration; the FDA label advises avoiding troughs above 10 mcg/mL and peaks above 35 mcg/mL, and states that the risk of hearing loss rises with exposure to either high peaks or high troughs. Nephrotoxicity is more likely with pre-existing renal impairment, dehydration, advanced age and concurrent nephrotoxic or ototoxic drugs (including potent loop diuretics and other aminoglycosides), and the label advises kidney function assessment before and daily during therapy. About 98% of an intramuscular dose is excreted unchanged within 24 hours with normal renal function, so clearance tracks glomerular filtration. Published trough targets vary by indication and population (for example under 5 mcg/mL in a neonatal TDM study and under 10 mcg/mL in a dialysis case report). With extended-interval regimens troughs are often undetectable by design, and LOINC has separate codes for post extended-interval samples. Peak targets are higher than for gentamicin or tobramycin and should not be shared with them. Conversion: 1 mcg/mL = 1 mg/L = 1.71 µmol/L (free base, MW 585.6).

LOINC 3321-7 (primary), 50803-6, 31098-7. Specimen: serum-or-plasma.

Sources

  1. Amikacin Sulfate Injection prescribing information (Dosage and Administration, Boxed Warning, Clinical Pharmacology), U.S. FDA label via NLM DailyMed (Hikma Pharmaceuticals) (2024)
  2. Therapeutic drug monitoring of amikacin in Chinese premature infant: a population pharmacokinetic analysis and dosage optimization, BMC Infectious Diseases (2025)
  3. Therapeutic drug monitoring of intravenous amikacin during peritoneal dialysis for Mycobacterium abscessus exit-site infection: a case report, Journal of Pharmaceutical Health Care and Sciences (2026)
  4. Amikacin (PubChem CID 37768), PubChem, National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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