44

Renal Physiology and

Pathophysiology

Daniel A. Shoskes; Alan W. McMahon

Questions

1.The AT1 receptor:

a.has a more pronounced vasoconstriction on the afferent rather than the efferent arteriole.

b.is the receptor for angiotensin I.

c.protects against ischemia-reperfusion injury by intrarenal dilation.

d.mediates increased release of aldosterone.

e.is not expressed in the kidney.

2.Which of the following statements about endothelin is FALSE?

a.Stimulation of endothelin-1 (ET-1) decreases sodium excretion.

b.Endothelin is the most potent vasoconstrictor yet identified.

c.ET-1 release is inhibited by nitric oxide.

d.ET-1 release stimulates aldosterone secretion.

e.ET-1 release reduces renal blood flow.

3.Which of the following is a vasodilator of the renal artery?

a.Endothelin

b.Carbon monoxide

c.Atrial natriuretic peptide

d.Norepinephrine

e.Angiotensin II

4.Which of the following statements is FALSE regarding carbon monoxide (CO) and the enzyme hemoxygenase?

a.Hemoxygenase-2 (HO-2) is a constitutive enzyme.

b.HO-1 is an inducible enzyme.

c.Increased CO increases ischemia-reperfusion injury in the kidney.

d.HO-1 expression helps to maintain renal medullary blood flow.

e.HO-1 produces CO through the catabolism of heme.

5.Which of the following statements regarding erythropoiesis is FALSE?

a.Reduced erythropoiesis and anemia are common in chronic renal disease.

b.Erythropoiesis is inhibited by low circulating oxygen tension.

c.During chronic inflammation, erythropoiesis is decreased.

d.The kidney makes most of the erythropoietin in the body.

e.There are erythropoietin receptors in many organs of the body.

6.Which of the following statements is TRUE about sodium and the kidney?

a.By definition, hypernatremia is always associated with elevated total body sodium content.

b.Normal compensation for hyponatremia is decreased antidiuretic hormone (ADH) secretion and thirst suppression.

c.Abnormal elevation of serum lipids can lead to a false, elevated measurement of serum sodium.

d.If asymptomatic hyponatremia does not improve within 24 hours, intravenous hypertonic saline should be started.

e.In therapy for symptomatic hyponatremia, the goal should be a normal serum sodium value of 135 mEq/L within 48 hours.

7.The syndrome of inappropriate antidiuretic hormone secretion (SIADH):

a.is associated with decreased aquaporin expression in the kidney.

b.is always seen in patients with hypervolemia.

c.is associated with high total body sodium.

d.is triggered by low circulating volume.

e.may be treated with lithium or demeclocycline.

8.Which of the following statements regarding therapy for hyponatremia is FALSE?

a.Fluid overload as a result of hypertonic saline infusion should be treated with a loop diuretic such as furosemide.

b.Too-rapid correction can lead to a cerebral demyelination syndrome.

c.Aggressive therapy should be discontinued when the serum sodium concentration is raised 10% or symptoms subside.

d.Intranasal desmopressin is a useful adjuvant therapy.

e.For acute severe hyponatremia with symptoms, a typical infusion rate of hypertonic saline would be 1 mL/kg/hr.

9.Diabetes insipidus:

a.may be classified as nephrogenic or urogenic.

b.is associated with inappropriately concentrated urine.

c.is associated with hypervolemia.

d.is associated with mutations of the genes producing aldosterone.

e.results in impairment of maximum concentrating ability of the kidney due to loss of the medullary osmotic gradient.

.Which of the following statements regarding potassium is FALSE?

a.Angiotensin-converting enzyme (ACE) inhibitors may be a cause of hypokalemia.

b.Potassium is primarily an intracellular ion.

c.Acidosis drives potassium out of the cell into the circulation.

d.High-sodium load in the distal tubule promotes potassium excretion.

e.Upper limit for safe intravenous potassium infusion is 40 mEq/hr.

.Which of the following statements regarding hyperkalemia is FALSE?

a.Hemolysis of the blood sample may falsely elevate the measured potassium.

b.Hyperkalemia can cause peaked T waves on the electrocardiogram (ECG).

c.All patients with a serum potassium value greater than 5.5 mEq/L require immediate therapy.

d.Nebulized albuterol can reduce serum potassium by promoting an intracellular shift of potassium.

e.Intravenous calcium does not lower serum potassium but is given to protect the heart from the effects of hyperkalemia.

.Which of the following statements is TRUE about acid handling?

a.Normal pH in the blood is 7.56 to 7.60.

b.Normal body metabolism produces less than 1000 mmol of acid per day.

c.All acids produced by metabolism can be excreted by the lungs.

d.Immediate response to an acid load is through buffers in the blood.

e.Ammonia (NH4) is the most important buffer in the blood.

.Which of the following statements regarding renal handling of acid is FALSE?

a.Most bicarbonate is reabsorbed in the distal collecting tubule.

b.Lungs can excrete volatile acid, but the kidneys must excrete fixed acid.

c.Carbonic anhydrase catalyzes the production of H+ and from H2O and CO2.

d.Chronic respiratory acidosis should lead to increased H+ in the kidney.

e.Ammonium ion (NH+4) is produced from glutamine, primarily by

proximal tubular cells.

.A patient who has a blood pH of 7.2 has:

a.pure metabolic acidosis.

b.pure respiratory acidosis.

c.acidemia.

d.a blood buffer system that is not working.

e.a mixed acid-base disturbance.

.In a patient with acidosis:

a.increasing the blood level increases the anion gap.

b.direct bicarbonate loss from the kidney would lead to metabolic acidosis and a normal anion gap.

c.lactic acidosis usually presents as a nonanion gap metabolic acidosis.

d.appropriate respiratory compensation for a metabolic acidosis is decreased respiration with an increased PCO2.

e.It is not possible to have both a respiratory and metabolic acidosis at the same time.

.Which of the following statements regarding renal tubular acidosis (RTA) is FALSE?

a.The hallmark of RTA type I is a hyperchloremic metabolic acidosis

with a high urinary pH (> 5.5) in the presence of persistently low serum .

b.Type I RTA is also called distal RTA.

c.Type II RTA is more common in children.

d.The hallmark of type IV RTA is hypokalemia.

e.The form of RTA most commonly associated with renal calculi is type I.

.Which of the following statements regarding metabolic alkalosis is FALSE?

a.Paradoxical aciduria may occur due to distal tubule injury.

b.Excessive nasogastric fluid loss can lead to metabolic alkalosis that is chloride responsive.

c.Appropriate respiratory compensation is decreased respiration and increased PCO2.

d.Hyperaldosteronism can lead to chloride-resistant metabolic alkalosis.

e.Therapy for chloride-responsive metabolic alkalosis requires replacement of chloride AND fluid volume.

.Which of the following is NOT a function of ADH?

a.Increased aquaporin-2 insertion into the luminal membrane of the collecting duct

b.Increased urea transporter insertion into the luminal membrane of the collecting duct

c.Increased systemic vascular resistance

d.Increased sodium reabsorption

e.Increased free water excretion in response to hypernatremia

.Which of the following statements is TRUE about vitamin D metabolism?

a.Vitamin D deficiency is uncommon in chronic renal failure.

b.Dermally synthesized cholecalciferol is the most potent form of vitamin D.

c.Dermally synthesized cholecalciferol must be hydroxylated by both the liver and kidney for maximal potency.

d.Vitamin D activity is mediated through membrane-bound vitamin D receptors.

e.Vitamin D increases renal excretion of calcium.

.Which of the following statements regarding parathyroid hormone (PTH) is FALSE?

a.PTH secretion is increased by hypocalcemia.

b.PTH secretion is increased by hyperphosphatemia.

c.PTH receptors are found mainly in bone and kidney.

d.PTH increases calcium and phosphorus reabsorption in the distal tubule.

e.PTH helps regulate 1,25(OH)-vitamin D levels by increasing 1αhydroxylase activity.

.Renal blood flow (RBF):

a.is equal in all parts of the kidney.

b.accounts for 5% to 10% of cardiac output.

c.courses through the glomerulus through the afferent arteriole and exits through the efferent venule.

d.is similar in men and women.

e.is one of the determinants of the glomerular filtration rate.

.All of the following can increase total glomerular flow rate (GFR) EXCEPT increased:

a.RBF.

b.intraglomerular (hydraulic) pressure.

a.It is responsible for the generation of a hypertonic medullary interstitium, which is necessary for urinary concentration.

b.It is able to increase or decrease reabsorption rates in response to changes in GFR.

c.The descending limb is highly water permeable.

d.The thin ascending limb actively reabsorbs sodium, chloride, and urea.

e.The thick ascending limb is impermeable to water.

.Which of the following statements about the thick ascending limb of the loop of Henle is FALSE?

a.Twenty-five percent of filtered sodium is actively reabsorbed by the furosemide-sensitive NKCC2 cotransporter.

b.Calcium and magnesium reabsorption is inhibited by furosemide.

c.Potassium is reabsorbed and returned to the systemic circulation by renal outer medullary potassium (ROMK) channels.

d.It is the site of uromodulin secretion.

e.Ten percent to 20% of filtered bicarbonate is reabsorbed in the thick ascending limb of the Henle loop (TALH).

.Regarding the distal convoluted tubule (DCT), all of the following statements are true EXCEPT:

a.The DCT reabsorbs 10% of filtered sodium by the thiazide-sensitive NCC cotransporter.

b.Sodium reabsorption is dependent solely on luminal sodium concentrations.

c.Calcium reabsorption is paracellular and influenced by sodium reabsorption.

d.Magnesium reabsorption is transcellular by luminal magnesium channels.

e.Loop diuretics increase sodium reabsorption in the DCT.

.All of the following statements are TRUE about the collecting tubule EXCEPT:

a.The collecting tubule is designed for fine tuning, rather than bulk transport, of ultrafiltrate.

b.Sodium reabsorption is regulated by aldosterone and occurs passively through luminal sodium channels.

c.Potassium reabsorption is dependent on both aldosterone and luminal flow rates.

d.The collecting tubule is impermeable to water at all times.