The Body Fluids and Kidneys

Question 1

Use the following clinical laboratory test results for questions 1 and 2:

Urine flow rate = 1 ml/min

Urine inulin concentration = 100 mg/ml

Plasma inulin concentration = 2 mg/ml

Urine urea concentration = 50 mg/ml

Plasma urea concentration = 2.5 mg/ml

1. What is the glomerular filtration rate (GFR)?

A)25ml/min

B)50 ml/min

C)100 ml/min

D)125ml/min

E)None of the above

Question 2

Use the following clinical laboratory test results for questions 1 and 2:

Urine flow rate = 1 ml/min

Urine inulin concentration = 100 mg/ml

Plasma inulin concentration = 2 mg/ml

Urine urea concentration = 50 mg/ml

Plasma urea concentration = 2.5 mg/ml

What is the net urea reabsorption rate?

A)0 mg/min

B)25 mg/min

C)50 mg/min

D)75 mg/min

E)100 mg/min

Question 3

Which of the following solutions when infused intravenously would result in an increase in extracellular fluid volume, a decrease in intracellular fluid volume, and an increase in total body water after osmotic equilibrium?

A)1 L of 0.9% sodium chloride solution

B)1 L of 0.45% sodium chloride solution

C)1 L of 3% sodium chloride solution

D)1 L of 5% dextrose solution

E)1 L of pure water

Question 4

A 65-year-old man has a heart attack and experiences cardiopulmonary arrest while being transported to the emergency room. The following laboratory values are obtained from arterial blood: plasma pH = 7.12, plasma PCO2= 60mm Hg, and plasma HCO3−concentration = 19 mEq/L.

Which of the following best describes his acid-base disorder?

A)Respiratory acidosis with partial renal compensation

B)Metabolic acidosis with partial respiratory compensation

C)Mixed acidosis: combined metabolic and respiratory acidosis

D)Mixed alkalosis: combined respiratory and metabolic alkalosis

Question 5

In the patient described in question 4, which of the following laboratory results would be expected,compared with normal?

A)Increased renal excretion of HCO3−

B)Decreased urinary titratable acid

C)Increased urine pH

D)Increased renal excretion of NH4+

Question 6

In normal kidneys, which of the following is true of the osmolarity of renal tubular fluid that flows through the early distal tubule in the region of the macula densa?

A)Usually isotonic compared with plasma

B)Usually hypotonic compared with plasma

C)Usually hypertonic compared with plasma

D)Hypertonic, compared with plasma, in antidiuresis

Question 7

The diagrams represent various states of abnormal hydration. In each diagram, the normal state (orange and lavender) is superimposed on the abnormal state (dashed lines) to illustrate the shifts in the volume (width of rectangles) and total osmolarity (height of rectangles) of the extracellular and intracellular fluid compartments.

Which of the diagrams represents the changes (after osmotic equilibrium) in extracellular and intracellular fluid volumes and osmolarities after the infusion of 1% dextrose?

Which of the diagrams represents the changes (after osmotic equilibrium) in extracellular and intracellular fluid volumes and osmolarities after the infusion of 3% sodium chloride?

Which of the diagrams represents the changes (after osmotic equilibrium) in extracellular and intracellular fluid volumes and osmolarities in a patient with the syndrome of inappropriate antidiuretic hormone (excessive secretion of antidiuretic hormone)?

Question 8

After receiving a renal transplant, a patient develops severe hypertension (170/110 mm Hg). A renal arteriogram indicates severe renal artery stenosis in his single remaining kidney, with a reduction in GFR to 25% of normal. Which of the following changes, compared with normal, would be expected in this patient, assuming steady-state conditions?

A)Large increase in plasma sodium concentration

B)Reduction in urinary sodium excretion to 25% of normal

C)Reduction in urinary creatinine excretion to 25% of normal

D)Increase in serum creatinine to about four times normal

E)Normal renal blood flow in the stenotic kidney due to autoregulation

Question 9

Which of the following tends to decrease potassium secretion by the cortical collecting tubule?

A)Increased plasma potassium concentration

B)A diuretic that decreases proximal tubule sodium reabsorption

C)A diuretic that inhibits the action of aldosterone (e.g., spironolactone)

D)Acute alkalosis

E)High sodium intake

Question 10

If a patient has a creatinine clearance of 90 ml/min, a urine flow rate of 1 ml/min, a plasma K+concentration of 4 mEq/L, and a urine K+ concentration of 60 mEq/L, what is the approximate rate of K+excretion?

A)0.06 mEq/min

B)0.30 mEq/min

C)0.36 mEq/min

D)3.6 mEq/min

E)60 mEq/min

Question 11

Which of the following changes would be expected in a patient with diabetes insipidus due to a lack of antidiuretic hormone (ADH) secretion?

Question 12

A patient with severe hypertension (blood pressure 185/110 mm Hg) is referred to you. A renal magnetic resonance imaging scan shows a tumor in the kidney, and laboratory findings include a very high plasma renin activity of 12 ng angiotensin 1/ml/hr (normal = 1). The diagnosis is a renin-secreting tumor. Which of the following changes would you expect to find in this patient, under steady-state conditions, compared with normal?

Question 13

Which of the following changes, compared with normal, would you expect to find 3 weeks after a patient ingested a toxin that caused sustained impairment of proximal tubular sodium chloride (NaCl) reabsorption? Assume that there has been no change in diet or ingestion of electrolytes

Question 14

A 26-year-old woman recently decided to adopt a healthier diet and eat more fruits and vegetables. As a result, her potassium intake increased from 80 to 160 mmol/day. Which of the following conditions would you expect to find 2 weeks after she increased her potassium intake, compared with before the increase?

Question 15

An 8-year-old boy is brought to your office with extreme swelling of the abdomen. His parents indicate that he had a very sore throat a “month or so” ago and that he has been “swelling up” since that time. He appears to be edematous, and when you check his urine, you find large amounts of protein being excreted. Your diagnosis is nephrotic syndrome subsequent to glomerulonephritis. Which of the following changes would you expect to find, compared with normal?

Question 16

Which of the following changes would you expect to find after administering a vasodilator drug that caused a 50% decrease in afferent arteriolar resistance and no change in arterial pressure?

A)Decreased renal blood flow, decreased GFR, and decreased peritubular capillary hydrostatic pressure

B)Decreased renal blood flow, decreased GFR, and increased peritubular capillary hydrostatic pressure

C)Increased renal blood flow, increased GFR, and increased peritubular capillary hydrostatic pressure

D)Increased renal blood flow, increased GFR, and no change in peritubular capillary hydrostatic pressure

E)Increased renal blood flow, increased GFR, and decreased peritubular capillary hydrostatic pressure

Question 17

A 32-year-old man complains of frequent urination. He is overweight (280 lb, 5 ft 10 in tall), and after measuring the 24-hr creatinine clearance, you estimate his GFR to be 150 ml/min. His plasma glucose is 300 mg/dL. Assuming that his renal transport maximum for glucose is normal, as shown in the figure above, what would be this patient’s approximate rate of urinary glucose excretion?

A)0 mg/min

B)100 mg/min

C)150 mg/min

D)225 mg/min

E)300 mg/min

F)Information provided is inadequate to estimate the glucose excretion rate

Question 18

The clinical laboratory returned the following values for arterial blood taken from a patient: plasma pH = 7.28, plasma HCO3− = 32 mEq/L, and plasma Pco2= 70 mm Hg. What is this patient’s acid–base disorder?

A)Acute respiratory acidosis without renal compensation

B)Respiratory acidosis with partial renal compensation

C)Acute metabolic acidosis without respiratory compensation

D)Metabolic acidosis with partial respiratory compensation

Question 19

Which of the following changes tends to increase peritubular capillary fluid reabsorption?

A)Increased blood pressure

B)Decreased filtration fraction

C)Increased efferent arteriolar resistance

D)Decreased angiotensin II

E)Increased renal blood flow

Question 20

Which of the following would cause the greatest degree of hyperkalemia?

A)Increase in potassium intake from 60 to 180 mmol/day in a person with normal kidneys and a normal aldosterone system

B)Chronic treatment with a diuretic that inhibits the action of aldosterone

C)Decrease in sodium intake from 200 to 100 mmol/day

D)Chronic treatment with a diuretic that inhibits loop of Henle Na+- 2Cl- -K+ cotransport

E)Chronic treatment with a diuretic that inhibits sodium reabsorption in the collecting ducts

Question 21

Which of the following is filtered most readily by the glomerular capillaries?

A)Albumin in plasma

B)Neutral dextran with a molecular weight of 25,000

C)Polycationic dextran with a molecular weight of 25,000

D)Polyanionic dextran with a molecular weight of 25,000

E)Red blood cells

Question 22

Under conditions of normal renal function, which of the following is true of the concentration of urea in tubular fluid at the end of the proximal tubule?

A) It is higher than the concentration of urea in tubular fluid at the tip of the loop of Henle

B)It is higher than the concentration of urea in the plasma

C)It is higher than the concentration of urea in the final urine in antidiuresis

D)It is lower than plasma urea concentration because of active urea reabsorption along the proximal tubule

Question 23

Which of the following changes would be expected in a patient with Liddle’s syndrome (excessive activity of amiloride-sensitive sodium channel in the collecting tubule) under steady-state conditions, assuming that intake of electrolytes remained constant?

Question 24

A patient’s urine is collected for 2 hr, and the total volume is 600 ml during this time. Her urine osmolarity is 150 mOsm/L, and her plasma osmolarity is 300 mOsm/L. What is her “free water clearance”?

A)+5.0 ml/min

B)+2.5 ml/min

C)0.0 ml/min

D)−2.5 ml/min

E)−5.0 ml/min

Question 25

A patient is referred for treatment of hypertension. After testing, you discover that he has a very high level of plasma aldosterone, and your diagnosis is Conn’s syndrome. Assuming no change in electrolyte intake, which of the following changes would you expect to find, compared with normal?

Question 26

A patient with renal disease had a plasma creatinine of 2 mg/dL during an examination 6 months ago. You note that his blood pressure has increased about 30 mm Hg since his previous visit, and the lab tests indicate that his plasma creatinine is now 4 mg/dL. Which of the following changes, compared with his previous visit, would you expect to find, assuming steady-state conditions and no changes in electrolyte intake or metabolism?

Question 27

Which of the following changes tends to increase GFR?

A)Increased afferent arteriolar resistance

B)Decreased efferent arteriolar resistance

C)Increased glomerular capillary filtration coefficient

D)Increased Bowman’s capsule hydrostatic pressure

E)Decreased glomerular capillary hydrostatic pressure

Question 28

The maximum clearance rate possible for a substance that is totally cleared from the plasma is equal to which of the following?

A)GFR

B)Filtered load of that substance

C)Urinary excretion rate of that substance

D)Renal plasma flow

E)Filtration fraction

Question 29

A patient has the following laboratory values: arterial pH = 7.13, plasma HCO3−= 15 mEq/L,plasma chloride concentration = 118 mEq/L, arterial Pco2= 28 mm Hg, and plasma Na+ concentration = 141 mEq/L. What is the most likely cause of his acidosis?

A)Salicylic acid poisoning

B)Diabetes mellitus

C)Diarrhea

D)Emphysema

Question 30

A 26-year-old man develops glomerulonephritis, and his GFR decreases by 50% and remains at that level. For which of the following substances would you expect to find the greatest increase in plasma concentration?

A)Creatinine

B)K+

C)Glucose

D)Na+

E)Phosphate

F)H+

Question 31

A patient with a history of frequent and severe migraine headaches arrives at your office complaining of stomach pain and breathing rapidly. She informs you that she has had a severe migraine for the past 2 days and has taken eight times the recommended dose of aspirin to relieve her headache during that time. Which of the following changes would you expect to find, compared with normal?