Calcium and Bone Disease

Question 1

what disorders cause hypercalcemia?

Answer 1

1. hyperparathyroidism (e.g. tumor)
2. increased bone resorption freeing Ca2+ (hormone imbalance)
3. increased gut absorption of Ca2+ (hormone imbalance)
4. decreased kidney excretion, retaining Ca2+ (hormone imbalance;
   kidney damage)

Question 2

what are the consequences of hyperparathyroidism?

Answer 2

causes hypercalcemia

Question 3

how does hyperparathyroidism cause hypercalcemia?

Answer 3

PTH is out of control, leading to increased ca levels

• normally ca levels suppress PTH transcription and secretion

Question 4

what is the role of calcitonin in treating hypercalcemia?

Answer 4

causes a rapid decline in serum ca and phosphate levels through its actions on bone.

• calcitonin acts faster than PTH preventing hypercalcemia
• inhibiting osteoclast mediated bone resorption

Question 5

what is a common cause of hypocalcemia?

Answer 5

corticosteroid medications such as prednisone

• reduces ca adsorption

Question 6

what are the common causes and consequences of hypercalcemia?

Answer 6

commonly due to overactive parathyroid glands.

• too much ca in blood can weaken bones, formation of kidney stones and interfere w heart and brain function

Question 7

what is rickets

Answer 7

condition that occurs in children when their bones are growing and have not yet fused

Question 8

what causes rickets

Answer 8

lack of vitamin D, leads to decreased levels of ca and phoshphate in the body. results in secondary hyperparathyroidism, PTH elevated and increased bone resorption

Question 9

what is best source of vitamin d?

Answer 9

exposure to sunlight

Question 10

what is osteomalacia

Answer 10

occurs in adults, where the mineralization of newly formed bone matrix is defective

Question 11

what are the causes of osteomalacia?

Answer 11

lack of vitamin D, low ca levels or low phosphate levels in adults w fused bone

Question 12

how is osteomalacia associated w osteoporosis?

Answer 12

both characterized by decreased bone density and strength

-In osteomalacia, there may be bowed femoral necks and pseudofractures, similar to symptoms seen in osteoporosis

Question 13

what is FGF23

Answer 13

a cytokine, specifically fibroblast-derived growth factor 23, that inhibits vitamin D production and blocks phosphate reabsorption in the kidney. Its dysregulation is linked to increased risk of rickets and osteomalacia

Question 14

where is FGF23 secretion and what stimulates this?

Answer 14

secreted by osteocytes and osteoblasts in response to oral phosphate loading or increased serum 1,25-dihydroxyvitamin D3 levels.

Question 15

what is significance of FGF23 and kidney dz?

Answer 15

is a marker for chronic kidney disease

Question 16

what is lytic pagets disease?

Answer 16

characterized by rapid bone loss due to accelerated bone turnover, rate of bone resorption or degradation is too high

Question 17

what is lytic pagets associated with?

Answer 17

with osteoarthritis

Question 18

what is used to treat lytic pagets?

Answer 18

calcitonin, it acts to inhibit osteoclast mediated bone resorption

Question 19

how does kidney deterioration contribute to vitamin D problems?

Answer 19

can lead to phosphate retention, which downregulates vitamin D production. Additionally, damaged kidneys may not be able to produce as much vitamin D. This results in decreased calcium levels, triggering a vicious circle of increased parathyroid hormone production

Question 20

what are some reasons for kidney problems?

Answer 20

diabetes, hypertension, accidents, injuries, etc

Question 21

how does renal secondary hyperparathyroidism develop?

Answer 21

develops when damaged kidneys cannot activate vitamin D in response to high PTH

• high PTH levels further downregulate vitamin D production

Question 22

what is Osteoporosis

Answer 22

is a disorder of the bones in which the bones become brittle, weak, and easily damaged or broken. A decrease in the mineralization and strength of the bones over time causes osteoporosis

Question 23

how is osteoporosis treated?

Answer 23

w calcitonin or hormone therapy, but maintaining health diet and exercise most important

Question 24

what proportion of individuals over 55 have low bone mass or osteoporosis?

Answer 24

approx 50%

Question 25

what factors contribute to development of osteoporosis?

Answer 25

decreasing bone mineral density with age, particularly in women due to lower levels of bone-strengthening androgens. Additionally, low estrogen levels and high glucocorticoids can contribute to osteoporosis by disrupting the balance between bone formation and resorption cycles. Long-term vitamin D insufficiency, decreased calcium absorption, smoking, and alcohol consumption are also risk factors for bone loss and osteoporosis

Question 26

is osteoporosis preventable?

Answer 26

largely w healthy lifestyle yes