Bone Diseases

Question 1

What is it called when one has too much calcium?

Answer 1

hypercalcemia

Question 2

What are four examples of disorders that cause hypercalcemia?

Answer 2

1) hyperparathyroidism
2) increased bone resorption freeing calcium
3) increased gut absorption of calcium
4) decreased kidney excretion

Question 3

What are the symptoms of hypercalcemia?

Answer 3

• anorexia, nausea, vomiting, renal salt and water loss
• extracellular fluid volume contraction
• decrease in calcium excretion (causes more hypercalcemia)

Question 4

What is the cause and effect of hyperparathyroid disease?

Answer 4

• causes hypercalcemia and other symptoms

- could result from a tumour

Question 5

What does hyperparathyroid do to calcium levels?

Answer 5

• usually calcium levels suppress parathyroid hormone transcription and secretion
• here parathyroid hormone is out of control and increases serum calcium

Question 6

What is used to treat hyperparathyroid?

Answer 6

• calcitonin
• causes rapid decline of serum calcium and phosphorous by acting on bone
• acts faster than parathyroid hormone

Question 7

What is calcitonin’s main function?

Answer 7

• inhibits osteoclast mediated bone resorption

Question 8

What are two possible causes of hypocalcemia?

Answer 8

• hypoparathyroid

- corticosteroid medications (ex. prednisone) which decrease calcium absorption

Question 9

What is a common symptom of hypocalcemia?

Answer 9

• muscle spasm

Question 10

What are some symptoms of hypercalcemia (hyperparathyroidism)?

Answer 10

• muscle twitching, anxiety, depression, confusion, personality changes

Question 11

What is rickets?

Answer 11

• occurs in children
• bones growing, not fused
• lack of vitamin D causes decrease in calcium and phosphate
• results in secondary hyperthyroidism and increased bone resorption

Question 12

What are some visual characteristics of a child with rickets?

Answer 12

• bow legs and humpback

Question 13

What program was implemented in Canada and US to decrease rickets?

Answer 13

• milk fortification

Question 14

What is osteomalacia?

Answer 14

• occurs in adults
• fused bone
• mineralization of newly formed bone matrix is defective

Question 15

What is osteomalacia caused by?

Answer 15

• lack of vitamin D, low calcium, or low phosphate

Question 16

There are many factors of rickets and osteomalacia including?

Answer 16

cytokines

Question 17

What is type I vitamin D deficiency?

Answer 17

• lack of vitamin D

- due to environment or genetic defect (defective enzyme)

Question 18

What is type II vitamin D deficiency?

Answer 18

• normal vitamin D levels but insensitive due to defect in receptor called alopecia

Question 19

What do laboratory, animal and epidemiologic evidence suggest about vitamin D and cancer?

Answer 19

• vitamin D may be protective against some cancers

Question 20

What happens if you have excessive sun exposure?

Answer 20

• does not result in vitamin D toxicity because the sustained heat on the skin photodegrades and nonactive products form

Question 21

What happens if you have excessive intake of vitamin D?

Answer 21

• long-term intake above the upper limit

- increase risk of vitamin D toxicity

Question 22

What is Lytic Paget’s disease?

Answer 22

• aka Osteitis Deformans

- rapid bone loss because of accelerated bone turnover (rate of bone resorption too high)

Question 23

What is Lytic Paget’s disease associated with?

Answer 23

• osteoarthritis

Question 24

What is used to treat Lytic Paget’s Disease?

Answer 24

calcitonin

Question 25

What is the pathogenesis of Renal Secondary Hyperparathyroidism?

Answer 25

• kidney deterioration causes vit D problem
• phosphate retention downregulates vitamin D and can’t produce as much in kidney
• decreases calcium and increase parathyroid hormone

Question 26

What is vitamin D normally upregulated by?

Answer 26

• low phosphorous, low calcium, high parathyroid hormone, low vitamin D

Question 27

How does parathyroid hormone get out of control due to kidney damage?

Answer 27

• usually vitamin D and calcium inhibit parathyroid hormone synthesis
• in damaged kidney, high parathyroid hormone not able to activate enough vitamin D and high phosphate downregulates vitamin D as well

Question 28

What is osteroporosis?

Answer 28

• decrease of bone mineral density

Question 29

What can be used to treat osteoporosis?

Answer 29

• calcitonin or hormone therapy

- healthy diet and exercise

Question 30

What causes osteoporosis?

Answer 30

• bone mineral density decreases with age
• low estrogen and high glucocorticoids
• long-term vitamin D insufficiency because of decreased calcium absorption

Question 31

What is bone health affected by?

Answer 31

• bone mass, bone architecture and body mechanics

- nutrition and hormones affect these

Question 32

What principle nutrients affect bone health?

Answer 32

• calcium, protein, potassium, magnesium, zinc, vitamins

Question 33

Which hormones affect the bones?

Answer 33

• vitamin D and parathyroid hormone

- also estrogen, testosterone, glucocorticoids and others

Question 34

What does estrogen do in relation to bone health?

Answer 34

• acts on osteoclasts and osteoblasts to inhibit bone breakdown
• stimulates bone formation

Question 35

What does testosterone do in relation to bone health?

Answer 35

• stimulates muscle growth (puts stress on bone and increases formation)
• source of estrogen (converted in fat cells)

Question 36

What contributes to bone loss?

Answer 36

• glucocorticoid excess

Question 37

What target cells have receptors for calcitriol (vitamin D)?

Answer 37

• intestine, kidney, bone, immune cells, breast, testicular tissue

Question 38

What cells have receptors for parathyroid hormone?

Answer 38

• kidney cells (uptake calcium into blood)
• bone osteoblasts and pre-osteoclasts that stimulate bone breakdown (release calcium into blood)
• no receptors in intestine but still has effect on vitamin D there

Question 39

What cells have receptors for calcitonin?

Answer 39

• osteoclasts