A male client has been receiving the antibiotic gentamicin sulfate, IV piggyback every 12 hours for several days. Which observation by the nurse indicates that the client may be experiencing an adverse effect of gentamicin? Reference Range: White Blood Cell 15,000 to 10,000/mm3 (5 to 10 x 10 L)]

A. White blood cell count of 6,000/mm³ (6 x 10³/µL): This WBC count is within the normal reference range and does not indicate an adverse effect of gentamicin. Neutropenia or leukopenia would be more concerning but are not typical gentamicin side effects. B. Reports of photophobia: Photophobia is not commonly associated with gentamicin toxicity. While it may indicate other issues, it is not a hallmark adverse effect of this antibiotic. C. Decreased blood urea nitrogen: Gentamicin toxicity is more often associated with increased BUN due to renal impairment. A decrease in BUN is not indicative of toxicity or adverse effects from gentamicin. D. Hearing has decreased: Ototoxicity is a well-known adverse effect of gentamicin, especially with prolonged use or higher doses. Hearing loss or tinnitus signals potential cochlear damage and requires immediate attention to prevent permanent hearing impairment.