A nurse in a clinic is planning care for a child who has ADHD and is taking atomoxetine.
Which of the following laboratory values should the nurse monitor?

The correct answer is Choice b: New onset of hearing loss.

Gentamicin, a potent aminoglycoside antibiotic, is renowned for its propensity to cause ototoxicity, particularly manifesting as new-onset hearing loss. Ototoxicity refers to damage to the inner ear structures responsible for hearing and balance, primarily the cochlea and vestibular apparatus. The mechanism of gentamicin-induced ototoxicity involves its accumulation in the endolymphatic fluid of the inner ear, leading to direct toxicity to the sensory hair cells and subsequent hearing impairment.

Manifestations of gentamicin-induced ototoxicity can vary, ranging from subtle high-frequency hearing loss to profound sensorineural deafness. Patients may experience tinnitus (ringing in the ears), difficulty hearing in noisy environments, and imbalance or vertigo. Notably, gentamicin-induced hearing loss is often irreversible and may progress even after discontinuation of the medication.

Now, let's delve into the rationales for the other choices:

Choice a: Hypotension Gentamicin administration is not typically associated with hypotension. However, systemic side effects such as nephrotoxicity and neurotoxicity can occur, particularly with prolonged or high-dose therapy. Nephrotoxicity may manifest as acute kidney injury, characterized by a rise in serum creatinine and blood urea nitrogen levels, oliguria, and fluid-electrolyte imbalances. Neurotoxicity, on the other hand, can lead to symptoms like muscle weakness, paresthesia, and confusion. Monitoring of blood pressure is essential in patients receiving gentamicin, but hypotension is not a direct adverse effect of the medication.

Choice c: Hyperthermia Gentamicin therapy is aimed at treating bacterial infections, such as pyelonephritis, and does not typically induce hyperthermia. Pyelonephritis itself is associated with fever, chills, and flank pain due to the inflammatory response to the urinary tract infection. Administration of gentamicin aims to eradicate the causative bacteria and resolve the underlying infection, which should, in turn, alleviate fever. However, persistent or worsening fever despite antibiotic therapy may indicate treatment failure or the presence of complicating factors, warranting further evaluation and management.

Choice d: Slurred speech Slurred speech is not a recognized adverse effect of gentamicin. Instead, it may suggest central nervous system involvement, such as cerebrovascular accidents (strokes), intoxication, or neurological disorders affecting speech production. Gentamicin primarily exerts its toxic effects on the inner ear structures, leading to auditory dysfunction rather than impairments in speech articulation. Therefore, the presence of slurred speech would prompt an assessment for alternative etiologies unrelated to gentamicin therapy.

In conclusion, while gentamicin is an effective antibiotic for treating infections, it carries the risk of ototoxicity, particularly manifested as new-onset hearing loss. Careful monitoring for this adverse effect is crucial to promptly identify and manage potential complications.