Endocrine II GMS 6419 Test Paper and Model
Answers.
A man has renal failure and is maintained on chronic hemodialysis until a donor kidney can be found. -
correct answers ✔️✔️Situation # 1
D
renal failure results in the inability to excrete PO4- so phosphate levels are raised -> resulting in
complexed Ca++ and lowered plasma calcium
& high levels of PO4- inhibit calcitriol metabolism, causing the inactive metabolite of VitD (24,25(OH)2D3
to be formed instead
calcitriol has a (-) feedback mechanism at the parathyroid - it switches off PTH synthesis and increases
CaSR synthesis in the chief cells
w/o the (-) feedback mechanism PTH syn/sec goes unchecked -> increased circulating PTH - correct
answers ✔️✔️1. This man exhibits increased circulating levels of PTH. Why?
A. Because of increased excretion of phosphate by the kidneys, leading to lowered circulating PO4-
B. Because of a lack of conversion of 25-(OH)D3 to 1,25-(OH)2D3 in the liver
, C. Because of increased absorption of calcium and phosphate from the intestine into the blood, and
increased circulating Ca2+
D. Because of a lack of 1,25-(OH)2D3 production by the kidneys, and therefore no inhibitory action of
this Vitamin D metabolite on PTH synthesis by the Chief Cells
D
administration of calcitriol [1,25 (OH)2D3] - correct answers ✔️✔️2. Assuming that this person is
receiving good medical care, which of the following would be an essential supplement to his
hemodialysis.
A. Daily injections of 25-(OH) D3
B. Plenty of exposure to sunlight
C. Chronic administration of rhPTH (Forteo)
D. Administration of 1, 25-(OH)2 D3
E. A diet rich in Vitamin D3
calcitonin - tones down calcium in blood inhibits bone resorption & stimulates Os.b
B - correct answers ✔️✔️3. Injection of calcitonin into this man during his maintenance period on
hemodialysis would cause:
A. A large excretion of calcium in the urine
B. Inhibition of bone breakdown
C. Increased synthesis of 25-(OH) D3
D. Increased production of 1, 25-(OH)2 D3
E. A large increase in bone resorption
a
Answers.
A man has renal failure and is maintained on chronic hemodialysis until a donor kidney can be found. -
correct answers ✔️✔️Situation # 1
D
renal failure results in the inability to excrete PO4- so phosphate levels are raised -> resulting in
complexed Ca++ and lowered plasma calcium
& high levels of PO4- inhibit calcitriol metabolism, causing the inactive metabolite of VitD (24,25(OH)2D3
to be formed instead
calcitriol has a (-) feedback mechanism at the parathyroid - it switches off PTH synthesis and increases
CaSR synthesis in the chief cells
w/o the (-) feedback mechanism PTH syn/sec goes unchecked -> increased circulating PTH - correct
answers ✔️✔️1. This man exhibits increased circulating levels of PTH. Why?
A. Because of increased excretion of phosphate by the kidneys, leading to lowered circulating PO4-
B. Because of a lack of conversion of 25-(OH)D3 to 1,25-(OH)2D3 in the liver
, C. Because of increased absorption of calcium and phosphate from the intestine into the blood, and
increased circulating Ca2+
D. Because of a lack of 1,25-(OH)2D3 production by the kidneys, and therefore no inhibitory action of
this Vitamin D metabolite on PTH synthesis by the Chief Cells
D
administration of calcitriol [1,25 (OH)2D3] - correct answers ✔️✔️2. Assuming that this person is
receiving good medical care, which of the following would be an essential supplement to his
hemodialysis.
A. Daily injections of 25-(OH) D3
B. Plenty of exposure to sunlight
C. Chronic administration of rhPTH (Forteo)
D. Administration of 1, 25-(OH)2 D3
E. A diet rich in Vitamin D3
calcitonin - tones down calcium in blood inhibits bone resorption & stimulates Os.b
B - correct answers ✔️✔️3. Injection of calcitonin into this man during his maintenance period on
hemodialysis would cause:
A. A large excretion of calcium in the urine
B. Inhibition of bone breakdown
C. Increased synthesis of 25-(OH) D3
D. Increased production of 1, 25-(OH)2 D3
E. A large increase in bone resorption
a
