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Interpretive Handbook

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Test 81749:
Vancomycin, Random, Serum

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Vancomycin is an antibiotic used to treat infections caused by gram-

positive organisms that are resistant to beta-lactam antibiotics, such

as methicillin-resistant staphylococci (MRSA), Staphylococcus

viridans group, penicillin/cephalosporin-resistant Streptococcus

pneumoniae, and penicillin/ampicillin-resistant Enterococcus

species. The oral formulation, which is not absorbed, is used in the

treatment of  pseudomembranous colitis caused by Clostridium difficile.

Vancomycin is also used when patients are intolerant or allergic to beta

lactams.

 

Vancomycin has been associated with nephrotoxicity and ototoxicity,

although it appears that many of these reports reflected impurities in

early formulations. Monitoring of vancomycin-related nephrotoxicity

is recommended only for patients with reduced renal function, those

receiving aggressive or prolonged vancomycin regimens, or those at

high risk including patients comedicated with other nephrotoxic agents.

 

Trough concentrations are recommended for therapeutic monitoring of

vancomycin, preferably acquired at steady state (just before fourth

dose). To avoid development of resistance, vancomycin trough levels

should remain >10  mcg/mL. Complicated infections require higher target

levels, typically 15 to 20 mcg/mL. Peak concentrations do not correlate

well to efficacy or nephrotoxicity, but may be useful for

pharmacokinetic studies or for select patients.

Useful For Suggests clinical disorders or settings where the test may be helpful

Monitoring adequacy of drug concentration during vancomycin

therapy

 

This unit code is used whenever a specimen is submitted

or collected without collection timing information. Random levels

may be ordered when attempting to determine when to dose

vancomycin in patients with renal impairment or those undergoing

dialysis.

Interpretation Provides information to assist in interpretation of the test results

Trough levels correlate better with efficacy than peak levels, with

target trough levels of 10 mcg/mL to 20 mcg/mL, depending on the

type of infection.

 

Peak levels are not recommended for monitoring, except in

select circumstances such as when performing pharmacokinetic

analyses (eg, area under the curve [AUC] determinations).

Typical peak levels are between 25 to 50 mcg/mL.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

VANCOMYCIN, TROUGH

Therapeutic concentration: 10.0-20.0 mcg/mL

Complicated infections: 15.0-20.0 mcg/mL

 

VANCOMYCIN, PEAK

Therapeutic concentration: 25.0-50.0 mcg/mL

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1.   Rybak M, Lomaestro B, Rotschafer JC, et al:  Therapeutic drug

      monitoring of vancomycin in adult patients: A consensus review

      of the American Society of Health-System Pharmacists, the

      Infectious Diseases Society of America, and the Society of

      Infectious Diseases Pharmacists.  Am J Health Syst Pharm

      2009;66:82-98

 

2.   Estes L, Wilson J:  Mayo Guide to Antimicrobial Therapy,

      Mayo Clinic, 2005-2008