Chemical Pathology

Notes

• Vancomycin levels can be taken at any time of day but the collection time should be convenient for the patient and for the testing laboratory – sampling and testing between 12 midnight and 6 am should be avoided – see "when to test"
• Most vancomycin levels are a planned non-urgent investigation
• Vancomycin levels are performed at Chemical Pathology on the GRH site – please send requests using a Chemical Pathology request form to avoid delays in sample receipt and analysis
• For requests out of hours please contact the on call biomedical scientist in Chemical Pathology to inform them that a sample is being sent

When to test

• Monitoring is required for patients receiving iv vancomycin but not po
• Only pre-dose (trough) levels are required.
• For adults, samples should be collected just before the 4th or 5th dose - earlier if there is renal compromise or the patient is on other nephrotoxic drugs

CrCl (ml/min)	Dose
>70	1 g bd. Check pre-dose level before fourth or fifth dose
50 - 70	750 mg bd. Check pre-dose level before fourth or fifth dose
20 - 50	500 mg bd. Check pre-dose level before third dose
10 - 20	500 mg od. Check pre-dose level before second dose
<10	500 mg every 48 hours. Check pre-dose level before second dose

 

• For paediatric patients, samples should be collected just before the 4th dose - earlier if there is renal compromise
• Normally levels can be monitored every 3 - 4 days if the initial level was satisfactory and renal function is stable
• For routine monitoring of pre-dose levels the patient should continue receiving subsequent dose(s) of vancomycin pending getting the results of the vancomycin levels back. Doses of vancomycin should not be omitted in these circumstances.
• When a patient is having a random vancomycin level checked to see if a high previous level has dropped to an acceptable level it is reasonable to withhold further doses of vancomycin until the results of the random vancomycin level are known. Circumstances when vancomycin should be withheld should be discussed with a specialist clinician.
• Different monitoring arrangements are required for the DCC vancomycin regime (see separate protocol) and for renal patients on haemodialysis receiving vancomycin.

Result interpretation

Normal levels:

• Pre-dose levels should be 10 - 15 mg/L routinely *
• Post-dose levels are NOT required

* Except where advised otherwise by a Consultant Microbiologist (eg pre-dose levels in staphylococcal endocarditis should be 15-20 mg/L)

The Consultant Microbiologist can advise on dose adjustment for abnormal levels, and repeat sampling, if necessary.

Normally levels can be monitored every 3 - 4 days if the initial level was satisfactory and renal function is stable.

 Sample Requirements

Samples must NOT be taken via lines

For Adults

• 5.0 mL of blood taken into a narrow gold top gel tube

For Small Children and Neonates

• A minimum of 1 mL of whole blood taken into a plain tube

Storage/transport

Store at fridge temperature

Transport as soon as possible at ambient temperature

Required information

Relevant clinical details

Information regarding time of sampling, dosing regime and start date of vancomycin must be included on the request form - this information is crucial for result interpretation

Turnaround time

Within 4 hours of receipt of the sample.

Results are made available on the computer as soon as they are approved.

Additional comments may be added later by the Consultant Microbiologist when results are reviewed.