Acute Renal Failure & Chronic Kidney Disease Practice Questions

Acute tubular necrosis is a type of acute renal failure the results primarily from____ and_____.
-renal ischemia

-nephrotoxic injury

Renal ischemia leads to acute tubular necrosis by disrupting the ________and causing patchy destruction of the_________
-basement membrane

-tubular epithelium

Nephrotoxic agents cause necrosis of the ______________that sloughs off and blocks the ______.
-tubular epithelium

-tubules

Acute tubular necrosis from nephrotoxic injury is more likely to be reversible because the
________________is usually not initially destroyed.
basement membrane

The nurse determines that a patient with oliguria has prerenal oliguria when:

a. urine testing reveals a low specific gravity.
b. the causative factor is malignant hypertension.
c. urine testing reveals a high sodium concentration.
d. reversal of the oliguria occurs with fluid replacement.

d. reversal of the oliguria occurs with fluid replacement.

Rationale: In prerenal oliguria, the oliguria is caused by a decrease in circulating blood volume, and there is no damage yet to the renal tissue. It can potentially be reversed by correcting the precipitating factor, such as fluid replacement for hypovolemia. Prerenal oliguria is characterized by urine with a high specific gravity and a low sodium concentration, whereas oliguria of intrarenal failure is characterized by urine with a low specific gravity and a high sodium concentration. Malignant hypertension causes damage to renal tissue and intrarenal oliguria.

Tubular damage is indicated in the patient with acute renal failure by a urinalysis finding of:

a. hematuria.
b. specific gravity fixed at 1.010.
c. urine sodium of 12 meq/l (12mmol/L).
d. osmolality of 1000 mOsm/kg (1000 mmol/kg).

b. specific gravity fixed at 1.010.

Rationale: A urine specific gravity that is consistently 1.010 and a urine osmolality of about 300 mOsm/kg is the same specific gravity and osmolality as plasma and indicates that tubules are damaged and unable to concentrate urine. Hematuria is more common with postrenal damage, and tubular damage is associated with a high sodium concentration (>40 mEq/L).

Metabolic acidosis occurs in the oliguric phase of acute renal failure as a result of impaired:

a. ammonia synthesis.
b. excretion of sodium.
c. excretion of bicarbonate.
d. conservation of potassium.

a. ammonia synthesis.

Rationale: Metabolic acidosis occurs in ARF because the kidneys cannot excrete H+, resulting in an increased acid load. Sodium is lost in urine because the kidneys cannot conserve sodium, and impaired excretion of potassium results in hyperkalemia. Bicarbonate is normally generated and reabsorbed by the functioning kidney to maintain acid-base balance.

Although both BUN and serum creatinine levels are increased in renal failure, a bun of 85 mg/dl (30.3 mmol/L) and a serum creatinine of 3.8 mg/dl (336 µmol/L) would most likely occur in a patient with acute renal failure caused by:

a. massive trauma.
b. bladder obstruction.
c. decompensated heart failure.
d. acute glomerulonephritis.

a. massive trauma.

Rationale: The normal BUN/creatinine ratio of 10:1 is increased in renal failure caused by conditions in which there is markedly increased catabolism, or breakdown of tissue, such as in severe injury, infections, or GI bleeding. The BUN is quite high in this case compared with the mild elevation of serum creatinine.

The nurse determines that a patient with acute renal failure is in the recovery phase when the patient experiences:

a. a return to normal weight.
b. a urine output of 3700 ml/day.
c. decreasing BUN and creatinine levels.
d. decreasing sodium and potassium levels.

c. decreasing BUN and creatinine levels.

Rationale: The BUN and creatinine levels remain high during the oliguric and diuretic phases of ARF. The recovery phase begins when the glomerular filtration returns to a rate at which BUN and creatinine stabilize and then decrease. Urinary output of 3 to 5 L/day, decreasing sodium and potassium levels, and fluid weight loss are characteristic of the diuretic phase of ARF.

While caring for the patient in the oliguric phase of acute renal failure, the nurse monitors the patient for associated collaborative problems, notifying the health care provider when:

a. urine output is 300 ml/24 hr.
b. edema occurs in the feet, legs, and sacral area.
c. the cardiac monitor reveals a depressed T wave and a sagging ST segment.
d. the patient experiences increasing muscle weakness and abdominal cramping.

d. the patient experiences increasing muscle weakness and abdominal cramping.

Rationale: Hyperkalemia is a potentially life-threatening complication of ARF in the oliguric phase. Muscle weakness and abdominal cramping are signs of the neuromuscular impairment that occurs with hyperkalemia, in addition to cardiac conduction abnormalities of peaked T wave, prolonged PR interval, prolonged QRS interval, and depressed ST segment. Urine output of 300 ml/day is expected during the oilguric phase, as is the development of peripheral edema.

true or false

The most common cause of death in acute renal failure is irreversible metabolic acidosis. (infection)

False

(infection)

true or false

Serum potassium and urea are increased during catabolism of body protein.

True

true or false

During the oliguric phase of acute renal failure, daily fluid intake is limited to 1000 ml plus the prior day’s measurable fluid loss.

False

600ml plus previous days total output

true or false

One of the most important nursing measures in managing fluid balance in the patient in acute renal failure is taking accurate daily weights.

True

true or false

Dietary sodium and potassium during the oliguric phase of acute renal failure are managed according to the patient’s urinary output.

False

(sodium and potassium serum levels)

A 68-year-old man with a history of heart failure secondary to hypertension has acute renal failure resulting from the effects of nephrotoxic diuretics. Currently his serum potassium is 6.2 mEq/L (6.2 mmol/L) with cardiac changes, his BUN is 108 mg/dl (38.6 mmol/L), his creatinine is 4.1 mg/dl (362 µmol/L), and his serum HCO3- is 14 mEq/L (14 mmol/L). He is somnolent and disoriented. What three criteria for treatment with dialysis does he meet?
a. Potassium above 6 mEq/L with cardiac changes

b. Bicarbonate level of 14 mEq/L, indicating metabolic acidosis

c. Change in mental status

A patient with acute renal failure has a serum potassium level of 6.8 mEq/L (6.8 mmol/L) and the following arterial blood gas results: pH 7.28, PaCO2 30 mm Hg, PaO2 86 mm Hg, HCO3- 18 mEq/L (18 mmol/L). The nurse recognizes that treatment of the acid-base problem would cause a decrease in the:

a. pH.
b. potassium level.
c. bicarbonate level.
d. the carbon dioxide level.

b. potassium level.

Rationale: During acidosis, potassium moves out of the cell in exchange for H+ ions, increasing the serum potassium level. Correction of the acidosis with sodium bicarbonate will help lower the potassium levels. A decrease in pH and the bicarbonate and PaCO2 levels would indicate worsening acidosis.

In replying to a patient’s questions about the seriousness of her chronic kidney disease, the nurse knows that the stage of chronic kidney disease is based on:

a. the total daily urine output.
b. the GFR.
c. serum creatinine and urea levels.
d. the degree of altered mental status.

b. the GFR.

Rationale: Stages of chronic kidney disease are based on the GFR or the presence of kidney damage over a period of 3 months. No specific markers of urinary output, azotemia, or urine output classify the degree of chronic kidney disease.

The nurse identifies a nursing diagnosis of risk for injury: fracture related to alterations in calcium and phosphorus metabolism for a patient with chronic renal disease. The pathologic process directly related to the risk for fractures is:

a. loss of aluminum through the impaired kidneys.
b. deposition of calcium phosphate in soft tissues if the body.
c. impaired vitamin D activation resulting in decreased GI absorption of calcium.
d. increased release of parathyroid hormone in response to decreased calcium levels.

c. impaired vitamin D activation resulting in decreased GI absorption of calcium.

Rationale: The calcium-phosphorus imbalances that occur in chronic kidney disease result in osteomalacia, osteitis fibrosa, and metatastic deposits of calcium phosphate, but pathologic fractures are most likely to occur from the osteomalacia resulting from hypocalcemia, which occurs from a deficiency of active vitamin D. Aluminum accumulation is also believed to contribute to the osteomalacia. Osteitis fibrosa involves replacement of calcium in the bone with fibrous tissue and is primarily a result of elevated levels of parathyroid hormone resulting from hypocalcemia.

A patient with chronic renal insufficiency weighs 70 kg and has the following laboratory results: creatinine clearance 18 ml/min; potassium 6.2 mEq/L (6.2 mmol/L); BUN 75 mg/dl (26.8 mmol/L), serum creatinine 6.3 mg/dl (557 µmol/L). An appropriate dietary modification for the patient is:

a. a protein restriction of 70 g/day.
b. a potassium restriction of 2 to 3 g/day.
c. a sodium restriction of 1000 mg/day.
d. unlimited intake of breads and cereals.

b. a potassium restriction of 2 to 3 g/day.

Rationale: Conservative management of the patient with renal insufficiency with an elevated potassium level would include a dietary potassium restriction of 2 to 3 g (51 – 76 mEq), a protein restriction of 0.6 to 0.8 g/kg (42 – 56 g for this patient), and moderate (2 – 3 g) restriction of sodium unless there is marked edema or hypertension. Breads and cereals are not allowed in unrestricted amounts because they contain protein.

The most appropriate snack/treat for the nurse to offer the patient with chronic renal disease is:

a. raisins.
b. ice cream.
c. dill pickles.
d. hard candy.

d. hard candy.

Rationale: A patient with chronic kidney disease may have unlimited intake of sugars and starches (unless the patient is diabetic), and hard candy is an appropriate snack/treat and may help relieve the metallic and urine taste common in the mouth. Raisins are a high-potassium food, pickled foods have high sodium content, and ice cream contains protein.