Final answer:
Increased creatinine levels should be reported immediately to the provider, as they can suggest impaired kidney function or damage, which is a particular concern with nephrotoxic drugs like gentamicin.
Step-by-step explanation:
The nurse should report increased creatinine levels immediately to the provider. Elevated creatinine levels can indicate impaired kidney function or kidney damage, which is a concern as gentamicin is known to be nephrotoxic and can potentially worsen kidney function. Monitoring renal function is crucial while a patient is receiving gentamicin.
An elevated white blood cell count could relate to the infection for which the patient is being treated. A decreased blood glucose level may require adjustment in therapy but is not directly related to gentamicin treatment. A low platelet count could be concerning for drug-induced thrombocytopenia, but its immediate report is not as urgent as changes in kidney function when considering gentamicin's known side effects.