Vancomycin (Random)
A vancomycin level drawn at any time, not tied to the dose schedule, which only makes sense along with when your last dose was given.
AI-verified against cited sources. Awaiting expert reviewLOINC 20578-1
Check your result
The usual range for Vancomycin random depends on age. Add your age above to see where you stand.
Nothing you type here leaves your browser.
What it is
Vancomycin is an antibiotic given by IV for serious infections, including MRSA. A random level is a blood sample taken at a time that is not specifically right before or right after a dose. On its own, the number has no fixed range. Your care team reads it with the dose time, the infusion end time and your kidney function. Dosing software can use one or two levels like this to estimate your total exposure over a day (the AUC).
Why it matters
Vancomycin needs enough exposure to treat the infection, and too much can harm the kidneys. Teams use random levels when kidney function is changing, when a timed trough is hard to get, or to see how fast the drug is leaving the body. A revised 2020 guideline recommends dosing serious MRSA infections by AUC, and a random level can be one of the inputs.
If it’s low
A low level soon after an infusion may mean the dose is smaller than your body needs. A low level many hours after a dose can be expected. Teams read it with the timing, so a single low number does not tell you much on its own.
Common causes
- A sample drawn long after the previous dose
- Fast kidney clearance, which can happen in younger or critically ill people
- Missed or delayed doses
- A larger volume of body fluid, for example after large IV fluid volumes
What can help
- Ask your team whether the level is being used to estimate your AUC
- Ask whether the timing of the draw was right
If it’s high
What counts as high depends on how long it has been since the dose. A level soon after an infusion is expected to be well above one drawn later. A level that is still high many hours after an infusion ended suggests the drug is leaving slowly, often because of reduced kidney function. Your team will read it with your dose times and your creatinine.
Common causes
- A sample drawn soon after the infusion ended
- Reduced kidney function or dehydration
- A recent dose increase
- A sample drawn from the IV line the drug runs through
- Other medicines that can strain the kidneys, such as aminoglycoside antibiotics or amphotericin B
What can help
- Ask your care team to record the exact times of your last dose and your blood draw
- Ask how your kidney function is being tracked
- Make sure the blood draw was not taken from the infusion line
What can affect your result
- Time between the end of the infusion and the blood draw
- Kidney function, hydration, age and body weight
- Whether the sample came from the infusion line
- Other medicines that affect the kidneys
- Without the time of the last dose, the number cannot be read: a level an hour after an infusion and a level before the next dose are expected to be very different.
- Drawing blood from the same IV line used for the infusion can falsely raise the result.
- Changing kidney function changes levels quickly.
- ARUP asks for a plain red-top serum tube separated from the cells within 2 hours.
Any time, but the exact time the sample was drawn and the time the last dose started and ended must be recorded. The half-life is 4 to 6 hours with normal kidney function (FDA labeling), so a level reflects the last dose or two. Much longer with poor kidney function.
When to talk to a clinician
Tell your care team promptly about much less urine, new swelling, ringing in the ears or hearing changes, or a new rash while you are on vancomycin. A typical hospital list asks the care team to call about random levels above 50 µg/mL, but limits vary widely. Call 911 or your local emergency number for trouble breathing, swelling of the face or throat, or fainting during or after an infusion.
Questions you could ask
- Are you using an AUC calculation to dose my vancomycin?
- How often will my levels and kidney tests be checked?
- Why was a random level chosen instead of a trough?
- How long after my dose was this level drawn?
- Should we check my kidney function again soon?
- Does this change my dose or the time between doses?
Questions people ask
Why is there no normal range for a random vancomycin level?
Because the number changes a lot with time. A level one hour after an infusion and a level just before the next dose are expected to be very different. Your care team compares your result with the dose time and often uses dosing software to estimate your overall exposure.
What is the difference between random, peak and trough levels?
A peak is drawn about an hour after an infusion ends, a trough is drawn right before the next dose, and a random level is drawn at some other time. A random level is useful when the exact times are recorded.
Show the science and sources
Units
- 1 µg/mL = 1 µg/mL
- 1 µg/mL = 1 mg/L
- 1 µg/mL = 0.69 µmol/L
Open the Vancomycin random unit converter
For clinicians and researchers
A random vancomycin concentration has no generic reference interval because it depends on the time since the dose and the infusion end time. Under the 2020 ASHP/IDSA/PIDS/SIDP guideline, AUC24 of 400–600 mg·h/L (assuming a MIC of 1 mg/L) is recommended for serious MRSA infections, and Bayesian software can estimate AUC from one or two levels at steady state or not. Vancomycin is eliminated almost entirely by glomerular filtration (half-life 4 to 6 hours with normal renal function), is about 55% protein bound and is not metabolized (FDA labeling). ARUP uses a KIMS immunoassay for its random test and lists no interval. A 2026 survey of US hospital critical limits found random limits listed by 30.9% of hospitals, with a median of 50 µg/mL and a range of 20–90, and described random limits as inconsistent with peak and trough limits. mg/L and µg/mL are the same unit.
LOINC 20578-1 (primary), 4091-5, 31012-8. Specimen: serum-or-plasma.
Sources
- Drug Critical Limits for Urgent Physician Notification, Clinical Pharmacology & Therapeutics (Kuang, Ibrahim, Cheng, Kost) (2026)
- Therapeutic monitoring of vancomycin for serious methicillin-resistant Staphylococcus aureus infections: A revised consensus guideline and review by the ASHP, IDSA, PIDS and SIDP, American Journal of Health-System Pharmacy (2020)
- Vancomycin Level, Random, Serum (test 3018771), ARUP Laboratories
- Vancomycin hydrochloride for injection prescribing information, DailyMed, National Library of Medicine
- Vancomycin (PubChem compound 14969), 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.