Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition
Chapter 79: Parathyroid Hormone, Calcitonin, Calcium and Phosphate Metabolism,
Vitamin D, Bone, and Teeth
Test Bank
1. A man consumes a high Ca2+ meal. Which of the following would be an appropriate
compensatory response to the postprandial changes in plasma [Ca2+] concentration?
A. Increased calcitonin secretion
B. Increased formation of 1,25-(OH)2D3
C. Increased osteoclastic activity
D. Increased renal Ca2+ reabsorption
E. Increased osteocytic osteolysis
2. Which of the following is not a direct effect of PTH?
A. Increased renal Ca2+ reabsorption
B. Decreased renal phosphate reabsorption
C. Increased intestinal Ca2+ and phosphate absorption
D. Increased Ca2+ and phosphate resorption from bone
E. Increased renal production of 1,25-(OH)2D3
3. Which of the following would cause the most rapid increase in free ionized plasma Ca2+
concentration?
A. Increased osteocytic osteolysis
B. Increased osteoclastic activity
C. Increased formation of 1,25-(OH)2D3
D. Increased renal Ca2+ reabsorption
E. Increased intestinal Ca2+ absorption
Questions 4-6: Match each of the following patients in questions 4 and 6 with the following
physiological changes.
Plasma [PTH] Plasma [1,25-(OH)2D3] Plasma [Phosphate]
A.
B.
C.
D.
E.
4. Most patients with rickets.
5. A patient with renal failure.
6. Most patients with osteomalacia.
7. A lethargic 60-year-old woman has complained of fatigue, depression, weakness, and
constipation for several years. She has been taking several over-the-counter vitamin
preparations for years. Abdominal x-rays reveal kidney stones and urine calcium is high.
Her PTH level is low. Which of the following is the most likely cause of her symptoms?
A. Vitamin D excess
B. Primary hyperparathyroidism
C. Secondary hyperparathyroidism
D. Surgical hypoparathyroidism
E. Poor exposure to sunlight
8. Which of the following would NOT be a prominent response to PTH?
A. Increased Ca2+ reabsorption in the proximal tubule
B. Increased osteocytic osteolysis
C. Increased osteoclastic activity
D. Increased formation of 1,25-(OH)2D3 in the proximal tubule
E. Decreased phosphate reabsorption in the proximal tubule
9. Which of the following would be expected in a patient with parathyroid deficiency 10
days postoperatively after inadvertent damage to the parathyroid glands?
A. Low plasma phosphate and Ca2+ levels and tetany
B. Low plasma [Ca2+] and increased muscular excitability
C. High plasma phosphate and Ca2+ levels and bone demineralization
D. Increased muscular excitability, a high plasma Ca2+ level, and bone demineralization
E. Increased calcitonin secretion
10. Which of the following would tend to increase plasma levels of ionized Ca2+
A. Increased plasma protein concentration
B. Increased osteoblastic activity
Test Bank
79-3
C. 1,25-(OH)2D3
D. Calcitonin
11. The site of formation of 1,25-dihydroxycholecalciferol is in which of the following?
A. Adrenal cortex
B. Skin
C. Renal cortex
D. Liver
E. Parathyroid gland
12. A 40-year-old woman comes to the emergency room with a fracture in the neck of the
femur. Radiographs reveal generalized demineralization of the bone in the area. Her
plasma calcium ion concentration is significantly greater than normal, 12.2 mg per cent.
Which of the following conditions is consistent with this presentation?
A. Osteoporosis
B. Rickets
C. Vitamin D deficiency
D. Hyperparathyroidism
E. Renal failure
13. Patients who are not exposed to ultraviolet light develop rickets for which of the
following reasons?
A. Calcium absorption from the intestine is depressed
B. Synthesis of parathyroid hormone is depressed
C. Conversion of 25,hydroxycholecalciferol to 1,25,dihydroxycholecalciferol is
depressed
D. Osteoblastic activity is increased
14. Which of the following cells secrete enzyme that break down collagen?
A. Osteocytes
B. Osteoblasts
C. Lymphocytes
D. Osteoclasts
15. Which of the following is the source of 1,25-dihydroxycholecalciferol?
A. The renal cortex
Test Bank
79-4
B. The parathyroid gland
C. The liver
D. The epithelium of the small intestine
16. Which of the following would be expected in a patient whose diet has been low in Ca2+
for 2 months?
A. Increased calbindin in the intestine
B. Increased plasma [phosphate]
C. Increased plasma [Ca2+]
D. Decreased osteoclastic activity
E. Decreased formation of 1,25(OH)2D3
17. Which of the following would most likely occur in a patient with primary
hyperparathyroidism?
A. Decreased synthesis [1,25(OH)2D3]
B. Decreased plasma [Ca2+]
C. Tetany
D. Increased plasma alkaline phosphatase activity
E. Increased plasma [phosphate]
18. Which of the following is not a compensatory response to a fall in plasma [Ca2+]?
A. Increased PTH secretion
B. Increased osteocytic osteolysis
C. Increased formation of 1,25(OH)2D3
D. Increased Ca2+ reabsorption
E. Increased phosphate reabsorption