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8.4 Calcitonin — Test 1
Q1. Calcitonin is secreted by the:✓ Parafollicular (C) cells of the thyroid
Q2. The main action of calcitonin is to:✓ Lower plasma calcium (inhibiting osteoclasts)
Q3. Calcitonin secretion is stimulated by:✓ A rise in plasma calcium
Q4. Calcitonin lowers calcium chiefly by acting on:✓ Osteoclasts (inhibiting bone resorption)
Q5. In adult humans, the physiological importance of calcitonin is:✓ Relatively minor (calcium is normal without it)
Q6. Match each hormone with its effect on plasma calcium and choose the correct option.✓ A-ii, B-i
Q7. Calcitonin can be used clinically to treat:✓ Acute hypercalcemia and Paget disease
Q8. Elevated calcitonin is a tumour marker for:✓ Medullary thyroid carcinoma (from C cells)
Q9. Calcitonin's effect on the kidney is to:✓ Increase calcium (and phosphate) excretion
Q10. Why does calcium remain normal in patients after total thyroidectomy (with parathyroids preserved)?✓ Calcitonin is not essential; PTH and vitamin D suffice
Q11. Calcitonin acts rapidly but its effect is:✓ Transient (osteoclasts escape over time)
Q12. Calcitonin opposes which hormone most directly?✓ Parathyroid hormone
Q13. Calcitonin secretion provides a mechanism to:✓ Rapidly limit a rise in plasma calcium
Q14. The cell type from which calcitonin originates is embryologically related to:✓ Neural crest (C cells)
Q15. In conditions of calcium loading (e.g. after a calcium-rich meal), calcitonin helps to:✓ Buffer the calcium rise by inhibiting bone resorption
Q16. Compared with PTH and vitamin D, calcitonin is unique in that it:✓ Lowers, rather than raises, plasma calcium
Q17. Salmon calcitonin is sometimes preferred therapeutically because it is:✓ More potent and longer-acting than human calcitonin
Q18. Calcitonin's role appears more significant during:✓ Growth, pregnancy and lactation
Q19. The overall calcium-regulating triad and their directions are:✓ PTH ↑, vitamin D ↑, calcitonin ↓ plasma calcium
Q20. Calcitonin measurement is clinically most useful for:✓ Diagnosing/monitoring medullary thyroid carcinoma