Endocrinology - Parathyroid Disorders and Endocrine Neoplasms Questions and Answers (100 %Score)

Endocrinology - Parathyroid Disorders and Endocrine Neoplasms


1. What are parathyroid glands composed of and what do they secrete?: Chief cells


- secrete, manufacture, and store parathyroid hormone


Also has small number of oxyphil cells

2. What does removal of 3 out of 4 parathyroid glands result in?: - transient hypoparathy-


roidism

3. What does removal of half the parathyroid glands result in?: - no major physiological


abnormalities

4. What is the primary action of PTH?: - increase serum calcium


5. What are the mechanisms of action of PTH?: - increases renal calcium reabsorption in the


distal tubule independently of sodium
- enhances intestinal calcium absorption
- stimulates bone resorption (breakdown of bone) by increasing osteoclastic activity

6. What does excess PTH lead to?: Hypercalcemia in extracellular fluid




,- rapid release of calcium salts from bone

7. What does reduced PTH levels lead to?: - hypocalcemia


8. How does PTH affect phosphate?: - decreases renal phosphate reabsorption


- increases renal phosphate excretion
- prevents calcium phosphate precipitation in tissues by lowering plasma phosphate as calcium rises


9. How does PTH cause renal phosphate excretion if it also causes increased


phosphate resorption from bone?: - renal phosphate excretion overrides increased phosphate re-


sorption from bone

10. What are the 3 main functions of PTH?: - increases intestinal absorption of calcium and


phosphate

- decreases calcium excretion by the kidneys
- increases phosphate excretion by the kidneys

11. How does activation of vitamin D by PTH increase serum calcium?: - PTH stimulates


conversion of Vitamin D to Calcitriol

- calcitriol increases dietary calcium absorption in the intestine




, 12. What are long term effects of elevated PTH?: - promoted net bone resorption


- inhibits osteoBlastic function
- enhances osteoClastic activity