A 65-year-old patient with pneumonia is receiving Gentamicin. It would be most important for a nurse to monitor which of the following laboratory values in this patient?

Appeared in: GMCH Chandigarh - 2019

Explanation

Gentamicin is an aminoglycoside antibiotic, a class of drugs known for causing significant nephrotoxicity (kidney damage) and ototoxicity (damage to the ear and hearing).
Blood Urea Nitrogen (BUN) and serum creatinine are the most direct and sensitive laboratory indicators of renal function.
An increase in BUN and creatinine levels is an early sign that the drug is affecting the kidneys, allowing for timely intervention to prevent irreversible damage.
Older adult patients, like the 65-year-old in the scenario, are at a higher risk for developing nephrotoxicity, making vigilant monitoring essential.

Option A: Gentamicin does not directly affect red blood cell production or volume. Monitoring hemoglobin and hematocrit is not a priority for detecting this drug's specific toxicities.
Option C: Gentamicin does not have a significant effect on platelets or the body's clotting cascade. This monitoring is not standard for aminoglycoside therapy.
Option D: While electrolyte imbalances (especially of potassium and magnesium) can occur with aminoglycoside-induced kidney damage, they are typically later signs. BUN and creatinine are earlier and more direct indicators of nephrotoxicity.

Clinical Relevance

Nursing practice connection: Use the key finding related to Monitoring for Adverse Effects of Aminoglycosides to guide bedside assessment, documentation, and the next nursing action.
Nurses must obtain baseline renal function tests (BUN, creatinine) before the first dose of Gentamicin and monitor these values throughout therapy, often daily or every 3 days.
It is a critical patient safety intervention to promptly report any rise in creatinine or BUN, a decrease in urine output, or patient complaints of tinnitus (ringing in ears) or vertigo to the provider.
Ensuring the patient is well-hydrated can help reduce the concentration of the drug in the kidneys, potentially lowering the risk of nephrotoxicity.

How to Approach the Question

First, identify the key drug in the question: Gentamicin.
Recall the drug's class and its major associated adverse effects. Gentamicin is an aminoglycoside, which is well-known for causing nephrotoxicity (kidney damage) and ototoxicity (ear damage).
Analyze the options provided. Each option represents a different set of laboratory tests that monitor different body systems.
Connect the drug's most common and serious adverse effect (nephrotoxicity) to the corresponding laboratory test. Kidney function is primarily measured by BUN and creatinine.
Select the option that directly monitors for this primary toxicity, as this represents the most important nursing action in this context.

Concept Tested & Keywords

Concept Tested: Monitoring for Adverse Effects of Aminoglycosides
Stem keywords: Gentamicin, 65-year-old, pneumonia, monitor, laboratory values
Lead-in keywords: most important
Clinical cues: Drug administered (Gentamicin) is known for specific toxicities (nephrotoxicity, ototoxicity).
Clinical cues: Patient age (65-year-old) increases the risk for drug-induced toxicity.

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E6 Pharmacology Katzung 16e p. 1286-1288

E6 Pharmacology Nursing Lilley 11e Part 2 p. 316-318

Practise the full GMCH Chandigarh - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.