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BONENT CHN practice questions

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Question 1Clinical Practice of Hemodialysis Nursing

Which finding best indicates that a new arteriovenous fistula has matured enough to be cannulated?

  1. A cool, pale hand distal to the access
  2. A palpable thrill with an audible bruit Correct answer.
  3. Blanching of the fingertips when the arm is raised
  4. Absence of any pulse over the vein

Explanation

A thrill on palpation and a bruit on auscultation reflect turbulent flow through a dilated outflow vein, the hallmark of maturation; most fistulas need several weeks of remodeling. Distal coolness, pallor, or absent pulsation point to ischemia or thrombosis rather than maturation.

Question 2Clinical Practice of Hemodialysis Nursing

During a hemodialysis treatment, which setting directly determines the volume of fluid removed from the patient?

  1. The ultrafiltration goal entered into the machine Correct answer.
  2. Blood flow rate
  3. The heparin bolus dose
  4. Dialysate temperature

Explanation

Ultrafiltration is the machine-controlled removal of plasma water, and the total volume removed equals the ultrafiltration goal plus any saline or fluid given during treatment. Blood flow, dialysate temperature, and heparin affect clearance, comfort, and clotting but not net fluid removal.

Question 3Clinical Practice of Hemodialysis Nursing

A patient becomes diaphoretic and keeps yawning 90 minutes into treatment, and the blood pressure is 82/48 mmHg. Which action should the nurse take first?

  1. Increase the ultrafiltration rate
  2. Administer an additional heparin bolus
  3. Document the finding and continue at the current settings
  4. Reduce or stop ultrafiltration and place the patient in Trendelenburg position Correct answer.

Explanation

Yawning, sweating, and a falling blood pressure are classic early signs of intradialytic hypotension caused by rapid volume removal. Decreasing or stopping ultrafiltration and improving venous return corrects the underlying problem promptly.

Question 4Clinical Practice of Hemodialysis Nursing

In a standard dialysate bath, which electrolyte is deliberately kept below the patient's plasma level so that it is removed during treatment?

  1. Bicarbonate
  2. Calcium
  3. Potassium Correct answer.
  4. Sodium

Explanation

Dialysate potassium is usually 1 to 3 mEq/L while plasma potassium is roughly 4 to 5 mEq/L, creating the gradient that drives diffusive removal. Sodium and bicarbonate are set near or above plasma levels, and calcium is set to match or slightly exceed the patient's level.

Question 5Clinical Practice of Hemodialysis Nursing

Which needle gauge is typically used to cannulate a mature arteriovenous fistula in an adult?

  1. 8 to 10 gauge
  2. 20 to 22 gauge
  3. 15 to 17 gauge Correct answer.
  4. 23 to 25 gauge

Explanation

Fistula needles are large bore, generally 15 to 17 gauge, so that blood flows of 300 to 450 mL/min can be delivered without excessive pressure. Smaller gauges cannot support these flows, and extremely large bore sizes are not manufactured for this purpose.

Question 6Clinical Practice of Hemodialysis Nursing

Which statement best describes a hemodialysis patient's estimated dry weight?

  1. The weight gained between two consecutive treatments
  2. The weight recorded before the very first dialysis treatment
  3. The weight measured immediately after a meal
  4. The weight at which the patient has no edema and tolerates the end of treatment without hypotension Correct answer.

Explanation

Estimated dry weight is the target post-treatment weight at which the patient is euvolemic, free of edema and pulmonary congestion, and stable hemodynamically. It is reassessed over time as appetite, residual function, and cardiac status change.

Question 7Clinical Practice of Hemodialysis Nursing

Which action best reduces the risk of an access-related bloodstream infection when cannulating an arteriovenous graft?

  1. Applying antibiotic ointment over the puncture sites after needle removal
  2. Wearing gloves without performing hand hygiene first
  3. Cleansing the site with an antiseptic and allowing it to dry completely before puncture Correct answer.
  4. Reusing the same tourniquet for the patient without cleaning it

Explanation

Antisepsis with friction followed by full air drying maximizes bacterial kill on the skin surface before the needle breaches it. Hand hygiene with gloves and single-use supplies are also required, and ointment at needle sites does not substitute for proper skin preparation.

Question 8Clinical Practice of Hemodialysis Nursing

Which laboratory test is used at the chairside to monitor the effect of unfractionated heparin during a dialysis treatment?

  1. Serum potassium
  2. Activated clotting time Correct answer.
  3. Hemoglobin
  4. Platelet count

Explanation

The activated clotting time reflects the intrinsic pathway and rises with heparin effect, so it is used to confirm adequate circuit anticoagulation. Hemoglobin, potassium, and platelets are monitored for anemia, electrolyte balance, and heparin-induced thrombocytopenia but do not measure acute heparin effect.

Question 9Clinical Practice of Hemodialysis Nursing

Thirty minutes before the end of treatment, a patient with a 4 kg ultrafiltration goal develops severe cramping in both calves. Which action is most appropriate?

  1. Give a hypotonic saline infusion
  2. Reduce the ultrafiltration rate and give a bolus of isotonic saline per protocol Correct answer.
  3. Massage the legs and continue the current settings
  4. Increase the ultrafiltration rate so the goal is met sooner

Explanation

Cramping near the end of treatment usually reflects rapid extracellular volume loss with vascular refilling lagging behind. Slowing ultrafiltration and giving isotonic saline restores intravascular volume while still permitting a safe completion of treatment.

Question 10Clinical Practice of Hemodialysis Nursing

Air is suspected in the venous blood line and the patient reports sudden dyspnea. In which position should the patient be placed?

  1. Prone position with the head turned
  2. High Fowler position with legs dependent
  3. Right lateral position with the head elevated
  4. Trendelenburg position, lying on the left side Correct answer.

Explanation

Trendelenburg positioning with the left lateral decubitus position traps air in the right ventricular apex away from the pulmonary outflow tract. The head-down tilt also promotes venous return while help is summoned and the pump is stopped.

Question 11Clinical Practice of Hemodialysis Nursing

A patient arrives for dialysis with a serum potassium of 6.9 mEq/L and peaked T waves on the ECG. Which dialysate potassium concentration is most appropriate for this treatment?

  1. 1.0 to 2.0 mEq/L Correct answer.
  2. A potassium-free bath for the entire treatment
  3. 3.0 mEq/L
  4. 4.0 mEq/L

Explanation

A low-potassium bath of about 1 to 2 mEq/L creates a steep gradient for rapid potassium removal in hyperkalemia with ECG changes. A completely potassium-free bath is generally avoided because it can produce rebound hypokalemia and arrhythmias later in the treatment.

Question 12Clinical Practice of Hemodialysis Nursing

Twenty minutes after needle removal, a patient's arteriovenous graft site is still oozing blood despite firm direct pressure. Which action should the nurse take?

  1. Massage the site to disperse the clot
  2. Continue direct pressure and notify the provider if bleeding persists Correct answer.
  3. Apply a light dressing and discharge the patient
  4. Reinsert a needle into the graft to tamponade the bleeding

Explanation

Prolonged post-cannulation bleeding may reflect excessive heparin, graft outflow problems, or a coagulopathy, so pressure is maintained while the provider is informed. Discharging a patient who is still bleeding risks significant blood loss outside the unit.

Question 13Clinical Practice of Hemodialysis Nursing

A patient's hemoglobin is 9.2 g/dL, ferritin is 45 ng/mL, and transferrin saturation is 12%. Which intervention is the priority?

  1. Increasing the erythropoiesis-stimulating agent dose alone
  2. Taking no action because the hemoglobin is acceptable
  3. Giving intravenous iron per protocol Correct answer.
  4. Transfusing two units of packed red blood cells

Explanation

A ferritin below 100 ng/mL with transferrin saturation under 20% indicates absolute iron deficiency, which blunts the response to erythropoiesis-stimulating agents. Iron repletion is therefore the priority before escalating the stimulating agent dose.

Question 14Clinical Practice of Hemodialysis Nursing

Midway through treatment the machine alarms for low dialysate conductivity and the patient reports nausea and headache. Which action is most appropriate?

  1. Give an antiemetic and continue the treatment
  2. Stop the pump, do not return the blood, and notify the team Correct answer.
  3. Increase the blood flow rate to improve clearance
  4. Decrease the dialysate temperature

Explanation

Abnormally low conductivity suggests a diluted or incorrectly mixed bath, which can cause hypotonic hemolysis with nausea, headache, chest or back pain, and dark plasma. The circuit is stopped and the blood is not returned because it may be hemolyzed, and the team must be notified immediately.

Question 15Clinical Practice of Hemodialysis Nursing

Five minutes after starting dialysis with a new dialyzer, a patient develops chest pain, dyspnea, and hypotension. Which cause is most likely?

  1. First-use (membrane bioincompatibility) reaction Correct answer.
  2. Dialyzer fiber leak
  3. Heparin-induced thrombocytopenia
  4. Air embolism

Explanation

A first-use reaction results from complement activation and bradykinin release when blood contacts a new membrane, producing symptoms within minutes of starting. The blood is not returned, the treatment is stopped, and the patient is supported while the reaction is reported.

Question 16Clinical Practice of Hemodialysis Nursing

How should a tunneled cuffed central venous dialysis catheter be cared for between treatments?

  1. Use the catheter routinely for drawing blood cultures
  2. Instill the prescribed locking solution into each lumen and keep the clamps closed Correct answer.
  3. Change the dressing daily with dry gauze
  4. Leave both lumens uncapped to allow drainage

Explanation

Each lumen is filled with the prescribed volume of locking solution (usually heparin or citrate per protocol) and clamped to prevent clotting and air entry. Strict aseptic technique at the hub and dressing per protocol limits catheter-related bloodstream infection.

Question 17Clinical Practice of Hemodialysis Nursing

Before cannulation, the nurse cannot palpate a thrill and hears only a faint bruit over the fistula. Which action is most appropriate?

  1. Notify the vascular access team and arrange alternative access for the treatment Correct answer.
  2. Cannulate the fistula as usual but at a lower blood flow
  3. Give an additional dose of heparin and reassess
  4. Apply a warm compress and proceed with cannulation

Explanation

Loss of thrill with a diminished bruit suggests failing flow or thrombosis, and cannulating such an access can destroy remaining vessels. Treatment proceeds through an alternative access while the access team evaluates the fistula urgently.

Question 18Clinical Practice of Hemodialysis Nursing

Which assessment finding best suggests that a patient has dropped below the estimated dry weight?

  1. A 2 kg weight gain since the previous treatment
  2. Bibasilar crackles on auscultation
  3. Postural hypotension with cramping near the end of treatment Correct answer.
  4. Periorbital edema

Explanation

Falling pressure on standing plus cramping late in treatment indicates that too much volume has been removed relative to the patient's true dry weight. Crackles, edema, and interdialytic weight gain all indicate the opposite problem of volume excess.

Question 19Clinical Practice of Hemodialysis Nursing

While inserting the arterial needle, the patient reports sharp pain and the site swells rapidly; the blood pump has not been started. What should the nurse do first?

  1. Start the pump at a low rate and observe the site
  2. Advance the needle farther to reach the vessel
  3. Stop, withdraw the needle, and hold pressure over the site Correct answer.
  4. Apply a tourniquet above the site and continue

Explanation

Rapid swelling with sharp pain indicates infiltration or penetration through the vessel wall, and the needle must be withdrawn promptly with sustained pressure to limit hematoma formation. A second needle or another site is then selected per protocol rather than pushing deeper.

Question 20Clinical Practice of Hemodialysis Nursing

A patient becomes unresponsive during dialysis and has no palpable pulse. What is the nurse's first priority?

  1. Finish the treatment quickly and then call for help
  2. Administer the next scheduled medication
  3. Call for help, start CPR, and disconnect the patient from the circuit Correct answer.
  4. Return the extracorporeal blood and give a heparin bolus

Explanation

Cardiac arrest requires activation of the emergency response and immediate high-quality chest compressions. The patient is separated from the extracorporeal circuit per unit protocol so resuscitation can proceed unimpeded.

Question 21Clinical Practice of Hemodialysis Nursing

A patient with a pre-dialysis BUN of 130 mg/dL begins a first-ever treatment. Two hours in, the patient reports headache, nausea, and confusion. Which is the most likely cause and initial action?

  1. Disequilibrium syndrome; reduce blood flow and stop or shorten the treatment Correct answer.
  2. Hypoglycemia; administer oral glucose
  3. Hypocalcemia; give intravenous calcium
  4. A seizure disorder; give the scheduled anticonvulsant

Explanation

Rapid urea removal from the blood creates an osmotic gradient that draws water into the brain, producing headache, nausea, confusion, and possibly seizures. Slowing or stopping the treatment reduces the osmotic shift and the provider is notified.

Question 22Clinical Practice of Hemodialysis Nursing

After six days of heparin exposure, a patient's platelet count falls from 250,000 to 78,000/µL and the arteriovenous graft clots. Which action is most appropriate?

  1. Stop all heparin exposure and notify the provider Correct answer.
  2. Switch to low-molecular-weight heparin and continue as before
  3. Transfuse platelets and continue the current heparin regimen
  4. Continue heparin and increase the dose

Explanation

A greater than 50% platelet drop with new thrombosis after several days of heparin strongly suggests heparin-induced thrombocytopenia, an antibody-mediated prothrombotic state. All heparin products are stopped and a non-heparin anticoagulant is ordered by the provider.

Question 23Clinical Practice of Hemodialysis Nursing

A patient's pre-dialysis BUN is 70 mg/dL and post-dialysis BUN is 21 mg/dL. What is the urea reduction ratio?

  1. 88%
  2. 49%
  3. 30%
  4. 70% Correct answer.

Explanation

Urea reduction ratio equals the pre-dialysis BUN minus the post-dialysis BUN, divided by the pre-dialysis BUN, times 100. Here 49 divided by 70 equals 0.70, or 70%, which meets the usual minimum adequacy target of 65%.

Question 24Clinical Practice of Hemodialysis Nursing

Which problem is most associated with routine use of a dialysate sodium concentration higher than the patient's serum sodium?

  1. Metabolic acidosis
  2. Increased thirst, greater interdialytic weight gain, and hypertension Correct answer.
  3. Intradialytic hypotension and cramping
  4. Hyperkalemia with peaked T waves

Explanation

A high-sodium bath limits the fall in serum osmolality and improves hemodynamic stability, but the resulting sodium load drives thirst and fluid intake between treatments. Over time this produces larger interdialytic gains, hypertension, and greater ultrafiltration demands.

Question 25Clinical Practice of Hemodialysis Nursing

Which set of findings most suggests acute hemolysis during a hemodialysis treatment?

  1. Clear plasma, hypertension, and bradycardia
  2. Fever, chills, and cloudy dialysate
  3. Frothy pink sputum with a rising hematocrit
  4. Port-wine colored plasma, back pain, and a falling hematocrit Correct answer.

Explanation

When red cells are destroyed in the circuit, free hemoglobin stains the plasma dark red, and the patient develops back or chest pain with a dropping hematocrit. The blood is not returned, the circuit is stopped, and the cause such as a hypotonic bath, overheated dialysate, or kinked line is investigated.

Question 26Clinical Practice of Hemodialysis Nursing

A patient is prescribed calcium acetate as a phosphate binder. When should the nurse teach the patient to take it?

  1. Once each morning one hour before breakfast
  2. At bedtime on an empty stomach
  3. With each meal and snack Correct answer.
  4. Only on days when the serum phosphorus exceeds 5.5 mg/dL

Explanation

Phosphate binders work by binding dietary phosphate within the intestinal lumen, so they must be present in the gut at the same time as food. Dosing is therefore linked to meals and snacks rather than to the clock or to a laboratory value.

Question 27Clinical Practice of Hemodialysis Nursing

Which set of findings indicates that an arteriovenous fistula meets the criteria for safe cannulation?

  1. A palpable thrill with a diameter of 3 mm and a depth of 10 mm below the skin
  2. Flow of 300 mL/min, diameter of 4 mm, and depth of 8 mm below the skin
  3. A bruit with a flow of 450 mL/min and a diameter of 5 mm at four weeks after creation
  4. Flow above 600 mL/min, diameter above 6 mm, and depth under 6 mm Correct answer.

Explanation

The commonly used rule of sixes describes a fistula that is at least six weeks mature, with flow above 600 mL/min, a diameter above 6 mm, a depth of 6 mm or less, and a straight cannulation segment of at least 6 cm. Fistulas that fall short are more likely to infiltrate or fail to deliver adequate blood flow.

Question 28Clinical Practice of Hemodialysis Nursing

How should the nurse obtain a valid post-dialysis BUN specimen from the arterial line?

  1. Draw the sample from the arterial line immediately after the blood pump stops
  2. Draw the sample from a peripheral vein 30 minutes after the treatment ends
  3. Draw the sample from the venous return line at the end of the treatment
  4. Slow flow for 15 seconds, then draw from the arterial line Correct answer.

Explanation

Slowing the blood flow to roughly 50 to 100 mL/min for about 15 seconds before sampling clears the line and access of recirculated, already-cleansed blood, which would falsely lower the BUN. An accurate post-treatment value is essential for calculating urea kinetics.

Question 29Clinical Practice of Hemodialysis Nursing

Midway through a treatment a patient becomes diaphoretic and nauseated with a blood pressure of 82/50 mmHg. What is the nurse's first action?

  1. Stop ultrafiltration, place in Trendelenburg, and give a saline bolus Correct answer.
  2. Give oral fluids and continue the treatment at the same blood flow and UF rate
  3. Increase the ultrafiltration rate so the treatment finishes on schedule
  4. Place the patient in reverse Trendelenburg and reduce the blood flow rate

Explanation

Symptomatic hypotension during dialysis reflects excessive intravascular volume removal, so the first priorities are to stop further volume loss, improve venous return to the heart, and restore circulating volume with isotonic saline. Treatment settings are then adjusted once the patient is stable.

Question 30Clinical Practice of Hemodialysis Nursing

A patient has recurrent intradialytic hypotension with no identifiable cause and tolerates the prescribed ultrafiltration poorly. Which dialysate change is most appropriate to request?

  1. Raise the dialysate sodium above 145 mEq/L
  2. Raise the dialysate calcium to 4.0 mEq/L
  3. Lower the dialysate temperature to 35 to 36 °C Correct answer.
  4. Raise the dialysate temperature to 39 °C

Explanation

Cooling the dialysate produces peripheral vasoconstriction, increases systemic vascular resistance, and helps maintain blood pressure during volume removal. It is a standard, low-risk intervention for patients with recurrent intradialytic hypotension.

Question 31Clinical Practice of Hemodialysis Nursing

A patient treated with a dialysate calcium of 2.0 mEq/L reports tingling around the mouth and in the fingers and now has a blood pressure of 88/54 mmHg. Which cause is most likely?

  1. Hypoglycemia
  2. Hypercalcemia
  3. Hypernatremia
  4. Hypocalcemia Correct answer.

Explanation

A low dialysate calcium creates a gradient that removes calcium from the patient, and perioral and acral paresthesias, cramps, and hypotension are classic features of hypocalcemia. Raising the dialysate calcium toward the patient's serum level corrects the problem.

Question 32Clinical Practice of Hemodialysis Nursing

A peripheral BUN is 90 mg/dL, the arterial line BUN is 84 mg/dL, and the venous line BUN is 30 mg/dL. What is the access recirculation percentage?

  1. 4%
  2. 6%
  3. 25%
  4. 10% Correct answer.

Explanation

Recirculation is calculated as (peripheral BUN minus arterial line BUN) divided by (peripheral BUN minus venous BUN), multiplied by 100. Using these values, (90 − 84) ÷ (90 − 30) × 100 equals 10%, which exceeds the acceptable threshold and suggests access dysfunction.

Question 33Clinical Practice of Hemodialysis Nursing

Which statement best describes transmembranous pressure during hemodialysis?

  1. TMP is fixed by the manufacturer and cannot be adjusted during a treatment
  2. TMP is the pressure generated by the dialysate pump alone during the treatment
  3. TMP equals the venous pressure reading minus the arterial pressure reading at the machine
  4. TMP is the blood-to-dialysate pressure gradient that drives ultrafiltration Correct answer.

Explanation

Transmembranous pressure is the difference in pressure across the dialyzer membrane between the blood compartment and the dialysate compartment. This gradient is the force that moves water and small solutes out of the blood, so it directly determines the ultrafiltration rate.

Question 34Clinical Practice of Hemodialysis Nursing

Thirty minutes into a treatment a patient develops chills, rigors, and a temperature of 38.9 °C without chest pain, dyspnea, or urticaria. Which cause is most likely?

  1. Pyrogen reaction from contaminated dialysate Correct answer.
  2. Air embolism through the venous line
  3. Disequilibrium syndrome
  4. First-use hypersensitivity to the dialyzer membrane

Explanation

Fever with rigors developing during treatment, without the chest or back pain and dyspnea of a hypersensitivity reaction, points to pyrogens or bacteria entering through the dialysate. The treatment should be stopped, the blood not returned to the patient, and the water and dialysate systems investigated.

Question 35Clinical Practice of Hemodialysis Nursing

A patient dialyzed against a bicarbonate concentration of 40 mEq/L becomes confused and drowsy, and the arterial blood gas shows a pH of 7.52 with an elevated bicarbonate. Which problem is most likely?

  1. Metabolic acidosis from inadequate dialysate bicarbonate
  2. Metabolic alkalosis from excessive dialysate bicarbonate Correct answer.
  3. Respiratory acidosis from hypoventilation during treatment
  4. High anion gap acidosis from retained uremic acids

Explanation

An elevated pH with a high serum bicarbonate defines metabolic alkalosis, which in dialysis usually results from a dialysate bicarbonate set higher than the patient needs. Consequences include hypoventilation, hypokalemia, hypocalcemic symptoms, and arrhythmias.

Question 36Clinical Practice of Hemodialysis Nursing

A patient is receiving heparin-free dialysis with periodic saline flushes. Which finding should the nurse monitor most closely to detect circuit clotting?

  1. Rising venous pressure with visible clot in the fibers Correct answer.
  2. The ultrafiltration goal achieved each hour
  3. Dialysate conductivity and pH measured at the machine
  4. Serum potassium trend across the treatment

Explanation

Without anticoagulation, clot formation in the dialyzer and venous chamber raises resistance and therefore venous pressure. Visual inspection of the fiber bundle and chambers, along with falling fiber volume and darkening blood, confirms developing clotting so the circuit can be replaced before it fails.

Question 37Clinical Practice of Hemodialysis Nursing

How should a heparin lock be instilled into a tunneled cuffed dialysis catheter after treatment?

  1. Fill each lumen with the marked volume plus an additional 0.5 mL
  2. Use the same volume for both lumens regardless of their length
  3. Instill 5 mL of heparin into each lumen regardless of catheter size
  4. Instill the priming volume marked on each lumen Correct answer.

Explanation

Each lumen has a stated priming volume, and the lock should exactly fill that volume to prevent clotting without injecting heparin into the systemic circulation. Overfilling risks bleeding and systemic anticoagulation, while underfilling leaves a dead space where thrombus can form.

Question 38Clinical Practice of Hemodialysis Nursing

A patient on maintenance hemodialysis reports pleuritic chest pain that eases when leaning forward, and a pericardial friction rub is heard. Which action is most appropriate?

  1. Give a rapid saline bolus and raise the blood flow rate
  2. Notify the provider and hold ultrafiltration pending evaluation Correct answer.
  3. Continue the treatment without changes and reassess at the next session
  4. Increase the ultrafiltration goal so the pericardial fluid is removed

Explanation

Uremic pericarditis is a serious complication that requires prompt evaluation for effusion and tamponade, and aggressive volume removal can precipitate cardiovascular collapse if tamponade is developing. The provider should be notified and fluid removal deferred while the patient is assessed.

Question 39Clinical Practice of Hemodialysis Nursing

A patient with an arteriovenous graft is treated at a blood flow of 350 mL/min. The pre-pump arterial pressure is now −240 mmHg, compared with −120 mmHg one week ago, the venous pressure is unchanged, and the arterial alarm keeps sounding. Which problem is most likely?

  1. Dialysate conductivity error
  2. Needle infiltration
  3. Arterial inflow stenosis Correct answer.
  4. Venous outflow stenosis

Explanation

A progressively more negative pre-pump pressure at an unchanged blood flow means the pump must generate greater suction to draw blood, indicating resistance on the arterial side such as inflow stenosis. Outflow problems instead raise venous pressure, and a normal venous pressure makes that unlikely.

Question 40Clinical Practice of Hemodialysis Nursing

During reprocessing, a dialyzer's total cell volume measures 78% of its original value. What is the appropriate action?

  1. Use it only for patients with a small body surface area
  2. Rinse it once more with dialysate and re-measure the total cell volume
  3. Return it to the reuse rack because 75% is the minimum accepted value
  4. Discard the dialyzer; it has failed the total cell volume criterion Correct answer.

Explanation

Total cell volume must remain at least 80% of the original value to ensure the fiber bundle retains enough surface area for adequate clearance. A value of 78% signals fiber loss and the dialyzer must be discarded rather than reused.

Question 41Renal Anatomy, Physiology, and Pathophysiology

The kidneys are best described as lying in which position?

  1. Intraperitoneal
  2. Intrathoracic
  3. Retroperitoneal Correct answer.
  4. Pelvic

Explanation

The kidneys sit behind the peritoneal cavity against the posterior abdominal wall, cushioned by perinephric fat. This retroperitoneal location explains why they can be biopsied or operated on without opening the peritoneum.

Question 42Renal Anatomy, Physiology, and Pathophysiology

What is the functional unit of the kidney?

  1. Nephron Correct answer.
  2. Glomerulus
  3. Renal corpuscle
  4. Collecting duct

Explanation

The nephron is the kidney's functional unit and consists of a renal corpuscle plus its tubule, where filtration and reabsorption occur. Each kidney contains roughly one million nephrons.

Question 43Renal Anatomy, Physiology, and Pathophysiology

Which hormone is produced by the kidney and stimulates red blood cell production?

  1. Aldosterone
  2. Natriuretic peptide
  3. Renin
  4. Erythropoietin Correct answer.

Explanation

Peritubular interstitial cells of the kidney release erythropoietin in response to tissue hypoxia, and it drives erythroid maturation in the bone marrow. Loss of this signal is a major cause of anemia in chronic kidney disease.

Question 44Renal Anatomy, Physiology, and Pathophysiology

What is the approximate normal glomerular filtration rate in a healthy adult?

  1. 90 mL/min
  2. 20 mL/min
  3. 125 mL/min Correct answer.
  4. 55 mL/min

Explanation

Normal GFR is about 125 mL/min, which corresponds to roughly 180 liters of filtrate per day. About 99% of that filtrate is reabsorbed, so final urine volume is far smaller.

Question 45Renal Anatomy, Physiology, and Pathophysiology

Which vessel delivers blood into the glomerular capillary tuft?

  1. Afferent arteriole Correct answer.
  2. Efferent arteriole
  3. Renal artery
  4. Peritubular capillary

Explanation

The afferent arteriole carries blood into the glomerulus, where filtration occurs. Blood then exits through the efferent arteriole, which is what allows glomerular pressure to be regulated.

Question 46Renal Anatomy, Physiology, and Pathophysiology

The largest share of filtered sodium is reabsorbed in which nephron segment?

  1. Medullary collecting duct
  2. Distal tubule
  3. Thick ascending limb
  4. Proximal tubule Correct answer.

Explanation

About two-thirds of filtered sodium and water is reclaimed in the proximal convoluted tubule, largely coupled to glucose, amino acid, and bicarbonate transport. More distal segments fine-tune the remaining load under hormonal control.

Question 47Renal Anatomy, Physiology, and Pathophysiology

Serum creatinine is measured clinically mainly to estimate which function?

  1. Tubular secretion
  2. Urine concentrating ability
  3. Bladder emptying
  4. Glomerular filtration Correct answer.

Explanation

Creatinine is generated at a steady rate by muscle, is freely filtered, and is only slightly secreted, so its serum level tracks the filtered load. This makes it a practical surrogate marker for glomerular filtration.

Question 48Renal Anatomy, Physiology, and Pathophysiology

Which hormone raises water permeability of the collecting duct?

  1. Atrial natriuretic peptide
  2. Aldosterone
  3. Antidiuretic hormone Correct answer.
  4. Parathyroid hormone

Explanation

Antidiuretic hormone binds V2 receptors on principal cells and inserts aquaporin-2 channels into the luminal membrane, allowing water to be reabsorbed. This concentrates the urine and reduces its volume.

Question 49Renal Anatomy, Physiology, and Pathophysiology

A patient has a BUN of 60 mg/dL and a serum creatinine of 1.0 mg/dL. This ratio most suggests which condition?

  1. Prerenal azotemia from volume depletion Correct answer.
  2. Chronic kidney disease stage 3
  3. Nephrotic syndrome
  4. Acute tubular necrosis

Explanation

A BUN-to-creatinine ratio above roughly 20:1 with a normal creatinine suggests urea is rising out of proportion to creatinine. Volume depletion enhances proximal urea reabsorption, and upper GI bleeding also raises the ratio.

Question 50Renal Anatomy, Physiology, and Pathophysiology

Aldosterone exerts its principal effect at which nephron site?

  1. Collecting duct Correct answer.
  2. Proximal tubule
  3. Descending limb
  4. Glomerular capillary

Explanation

Aldosterone acts on principal cells of the collecting duct, increasing sodium reabsorption through ENaC and enhancing potassium secretion. The result is sodium retention with potassium loss.