Hormone Regulation of Ca (lecture)

Question 1

What are the two main Ca regulating signals and their effects?

Answer 1

PTH: incr. bone resorption, renal resorption, and 1-hydroxylase (Vitamin D activator)
Vit D: Incr. intestinal absorption of Ca, increase bone resorption

Question 2

What are the three forms of Ca found in the body and the relative distribution?

Answer 2

45 - 50% - ionized
5 - 10% - Ca-salt complex
40 - 50% is protein bound

Question 3

What three organs are involved in Vit D synthesis?

Answer 3

Skin: UV light makes D2 and D3
Liver: hydroxylase makes D-25
Kidney: hydroxyls makes 1, 25 - (OH)2-D3

Question 4

What is the single most important thing a person can do to prevent osteoporosis?

Answer 4

Build bone early in life through goo diet and exercise (weight bearing)

Question 5

What are the three Rx options for osteoporosis, which is preferred and why?

Answer 5

Hormone replacement (high risk of CVD and cancer)
Bisphosphonates (-dronate) have fewer side effects
Denosumab blocks RANKL - expensive

Question 6

What is the MoA of bisphosphonates?

Answer 6

Bind to bone mineral and are taken up by osteoclasts, then disables them