The most common cause of acute kidney injury in critically ill patients is
- A. sepsis.
- B. fluid overload.
- C. medications.
- D. hemodynamic instability.
Correct Answer: A
Rationale: The correct answer is A: sepsis. Sepsis is a leading cause of acute kidney injury in critically ill patients due to the systemic inflammatory response leading to kidney damage. Fluid overload (B) can contribute but is not the primary cause. Medications (C) and hemodynamic instability (D) can also lead to acute kidney injury but are not as common as sepsis in critically ill patients.
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Renin plays a role in blood pressure regulation by
- A. activating the renin-angiotensin-aldosterone cascade.
- B. suppressing angiotensin production.
- C. decreasing sodium reabsorption.
- D. inhibiting aldosterone release.
Correct Answer: A
Rationale: The correct answer is A because renin activates the renin-angiotensin-aldosterone cascade. Renin is released by the kidneys in response to low blood pressure or low sodium levels. It acts on angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme. Angiotensin II causes vasoconstriction, leading to increased blood pressure, and stimulates aldosterone release, promoting sodium and water retention.
Choice B is incorrect because renin does not suppress angiotensin production; it actually initiates the process. Choice C is incorrect because renin's action leads to increased sodium reabsorption by stimulating aldosterone release. Choice D is incorrect because renin does not inhibit aldosterone release; it promotes it as part of the renin-angiotensin-aldosterone cascade.
The nurse is caring for a patient with a diagnosis of head trauma. The nurse notes that the patient’s urine output has increased tremendously over the past 18 hours. The nurse suspects that the patient may be developing
- A. diabetes insipidus.
- B. diabetic ketoacidosis.
- C. hyperosmolar hyperglycemic syndrome.
- D. syndrome of inappropriate secretion of antidiuretic hormone.
Correct Answer: A
Rationale: Rationale: A patient with head trauma may develop diabetes insipidus due to damage to the hypothalamus or pituitary gland, leading to decreased secretion of antidiuretic hormone (ADH). This results in excessive urine output and thirst. Other options are incorrect because:
B: Diabetic ketoacidosis is associated with high blood sugar and ketones, not increased urine output.
C: Hyperosmolar hyperglycemic syndrome is characterized by extreme hyperglycemia, not increased urine output.
D: Syndrome of inappropriate secretion of antidiuretic hormone results in decreased urine output due to excess ADH.
Conditions that produce acute kidney injury by directly acting on functioning kidney tissue are classified as intrarenal. The most common intrarenal condition is
- A. prolonged ischemia.
- B. exposure to nephrotoxic substances.
- C. acute tubular necrosis (ATN).
- D. hypotension for several hours.
Correct Answer: C
Rationale: Rationale: Acute tubular necrosis (ATN) is the most common intrarenal condition causing acute kidney injury. ATN is characterized by damage to the renal tubules due to ischemia or nephrotoxic substances. Prolonged ischemia (choice A) and exposure to nephrotoxic substances (choice B) can lead to ATN. Hypotension for several hours (choice D) can result in ischemic injury, which may lead to ATN but is not the direct cause. Therefore, choice C is correct as it directly relates to the primary intrarenal condition of ATN.
The patient is complaining of severe flank pain when he tries to urinate. His urinalysis shows sediment and crystals along with a few bacteria. Using this information along with the clinical picture, the nurse realizes that the patient’s condition is
- A. prerenal.
- B. postrenal.
- C. intrarenal.
- D. not renal related.
Correct Answer: C
Rationale: The correct answer is C: intrarenal. The presence of sediment, crystals, and bacteria in the urinalysis indicates an issue within the kidneys themselves. The flank pain suggests renal involvement. Prerenal would involve issues before the kidneys, such as inadequate blood flow. Postrenal would involve issues after the kidneys, such as urinary tract obstruction. Not renal related is incorrect as the symptoms and urinalysis findings clearly point to a renal issue.
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 if a reliable 24-hour urine collection is not possible, a standardized formula can be used to estimate the GFR. This is typically done using the patient's serum creatinine level, age, sex, and race. It is a validated method when direct measurement is not feasible.
A: Incorrect. It is still possible to estimate GFR using formulas when 24-hour urine collection is not possible.
B: Incorrect. BUN alone is not sufficient to accurately determine renal function.
C: Incorrect. BUN/Creatinine ratio is not a direct measure of GFR and may be influenced by other factors.