The nurse prepares to administer vancomycin (Vancocin) to an older adult. Which laboratory test should the nurse review before administering this medication?

Question

a. Stool culture c. Creatinine clearance
b. Serum potassium d. Alkaline phospha-tase

Answer 1

C
Antibiotics, as a group of drugs, are hard on the kidneys; thus the nurse should check the creati-nine clearance of this individual. Although approximately 30% of absorbed vancomycin is pro-tein bound, it is cleared by the kidneys, and creatinine clearance is the best index available of renal function. Because approximately 70% of vancomycin circulates in the bloodstream in the active form, the dose must be reduced or the dosing intervals increased to maintain the desired drug level and to prevent toxicity in the older adult who has renal dysfunction. The pathogen is already identified; however, some value can be obtained from subsequent stool cultures to de-termine whether the infection is eradicated. Serum potassium is a reasonable parameter to check in an older adult; however, if used as a measure of renal function, then the creatinine clearance is a better choice. Alkaline phosphatase is a measure of hepatic function and a reasonable parameter to check when administering medications; hepatic clearance is important in the metabolism of many medications.