Critical Care Nursing Cardiac Questions Related

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In determining the glomerular filtration rate (GFR) or creatinine clearance, a 24-hour urine is obtained. If a reliable 24-hour urine collection is not possible,

  • A. it is not possible to determine the GFR.
  • B. the BUN may be used to determine renal function.
  • C. an elevated BUN/creatinine ratio can be used.
  • D. a standardized formula may be used to calculate GFR.
Correct Answer: D

Rationale: The correct answer is D because when a reliable 24-hour urine collection is not possible, a standardized formula can be used to estimate GFR. The Cockcroft-Gault equation or the Modification of Diet in Renal Disease (MDRD) equation are commonly used formulas to estimate GFR based on serum creatinine levels, age, gender, and race. These formulas provide a reasonable estimation of kidney function in the absence of a 24-hour urine collection.

Choice A is incorrect because there are alternative methods available to estimate GFR. Choice B is incorrect because BUN alone is not sufficient to accurately determine renal function. Choice C is incorrect because an elevated BUN/creatinine ratio is not a direct measure of GFR and may be influenced by factors other than kidney function, such as hydration status or liver function.