Nutrition / Drugs for Osteoporosis / Ca Disorders

Question 1

Does Ca carbonate need to be taken with food?

Answer 1

Yes

Question 2

Does Ca citrate need to be taken with food?

Answer 2

No

Question 3

CaSR agonist
Name of drug
Use

Answer 3

Cinacalcet
Suppresses abnormally high PTH
Used for parathyroid carcinoma and secondary hyperparathyroidism due to ESRD / HD.

Question 4

PTH-independent Ca handling in kidney

Answer 4

• 65% of Ca is passively resorbed in proximal tubule. Paracellular.
• Uptake in thick ascending limb driven by V-gradient created by Na/K/Cl reabsorption.
• High Ca levels sensed by renal CaSR → inhibition of Na/K/Cl channel → inhibits Ca reabsorption

Question 5

PTH-dependent Ca handling in kidney

Answer 5

Na/Cl cotransporter triggers opening of Ca channel in distal convoluted tubule

Question 6

Effects of loop diuretics (furosemide) and thiazide diuretics on Ca

Answer 6

• Loop diuretics (furosemide) blocks Na/K/Cl transport. Used to treat hypercalcemia. Only use in pxs w/ adequate volume expansion
• Thiazide diuretics are used to treat hypercalciuria (too much Ca in urine). Blocks the Na/Cl cotransporter in the DCT → opening of V-gated Ca channel → Ca resorption. Work at the same place as PTH.

Question 7

Treating hypocalcemia due to hypoparathyroidism

Answer 7

Give Ca and calcitriol.

Question 8

Effects of E2 and PTH on bone

Answer 8

Increases growth / maturation of osteoblasts and decreases apoptosis.

Question 9

E2 effect on OPG and osteoclasts

Answer 9

Upregulates OPG and osteoclast apoptosis.

Question 10

Effects of E2 and PTH on RANKL

Answer 10

RANKL is increased by PTH, decreased by E2

Question 11

Efficacy of raloxifene
Adverse rxns (2)

Answer 11

Good at decreasing risk of vertebral fracture, but not effect on hip or other fracures.
Adverse rxns - hot flashes and risk of thrombosus.

Question 12

4 bisphosphonates
Efficacy of each
Side effects (4)

Answer 12

• Alendronate – decreases risk of fracture by 50%
• Risedronate – same as alendronate
• Ibandronate – only useful for vertebral fractures. Not recommended.
• Zoledronic acid – Most potent. Reduces fractures by 70%. 1/3 of pxs have an acute phase rx w/ 1st infusion (fever / myalgias).
• Side effects
• Heartburn – important to take on empty stomach, drink 8 oz water, and remain upright for 30 min.
• Osteonecrosis of the jaw
• Atypical femoral fractures

Question 13

Denosumab
Type of drug
Mechanism

Answer 13

Monoclonal Ab to RANKL (similar to OPG).

Decreases activation of osteoclasts.

Question 14

Only anabolic drug
Name
Mechanism
Efficacy
Requirement
Side effects

Answer 14

• Teriparatide
• Short-acting recombinant PTH analog
• Increases BMD by 10%. Decreases fractures by >50%.
• Requirement: Bone gains are quickly lost when drug is stopped, so antiresorptive agent must be used to “seal in” the gains.
• Side effects – nausea, dizziness, weakness