The practical nurse (PN) is caring for an older client who is receiving chemotherapy for lung cancer. Which finding is the highest priority for the PN to report to the charge nurse? Reference ranges: Blood urea nitrogen (BUN): [Adult: 10 to 20 mg/dL or 3.6 to 7.1 mmol/L] Platelets: [150,000 to 400,000/mm3 or 150 to 400 x 10^9/L]