Calcium homeostasis

Question 1

Vitamin D stimulates intestinal abs of Ca and P

Answer 1

:)

Question 2

PTH and Vit D effect of bone:

Answer 2

Formation via osteoblasts

Resorption via osteoclasts

Question 3

PTH and Vit D effect on kidney:

Answer 3

Enhance resorption of Calcium
PTH: stimulates renal excretion of P
Vit D: enhances P retention

Question 4

Fibroblast growth factor effect at kidney:

Answer 4

Stimulates excretion of P, overall decreases serum level

Question 5

PTH stimulates Vit D activation at kidney

Answer 5

:)

Question 6

Vit D and Ca++ inhibit PTH synthesis and release

Answer 6

negative feedback

Question 7

Fibroblast growth factor inhibits VIt D in kidney

Answer 7

:)

Question 8

Calcitonin (synthetic) can reduce serum Ca and P by inhibiting bone resorption

Answer 8

:)

Question 9

Vitamin D3 (cholecalciferol)

Answer 9

Modest cost. Efficient

Question 10

Vitamin D2 (ergocalciferol)

Answer 10

Less efficient than D3, shouldnt be 1st choice

Question 11

25-Hydroxyvitamin D3 (calcifediol)

Answer 11

DOesnt need hepatic hydroxylation. Best for liver disease

Question 12

1, 25-dihydroxyvitamin D3 (calcitriol)

Answer 12

Most useful in patients with decreased synthesis of calcitriol (renal disease)

Question 13

Calicitriol synthesis stimulated by

Answer 13

PTH in the kidney (released in response to hypocalcemia)

Hypophosphatemia also directly stimulates synthesis

Question 14

Calcitonin stimulated by, MOA

Answer 14

Hypercalcemia
inhibits bone resorption –> decreases Ca++ and PO4
Reduces absorption/increases excretion of Ca++ and PO4

Question 15

Estrogen MOA

Answer 15

Decreases number and activity of osteoclasts

Increase osteoblast activity

Question 16

Glucocorticoid MOA on decreasing bone density

Answer 16

Lowers serum Ca++ by inhibiting dietary absorption –> increases PTH in response, increased osteoclast activity
Activates osteoclasts –> increased bone resorption
Suppresses osetoblast activity

Question 17

RANK ligand is expressed on an osteoblast in response to

Answer 17

Vitamin D3, PTH and interleukins

Question 18

RANKL interacts with receptor (RANK) on osteoclast

Answer 18

forms mature osteoclasts

Question 19

Bisphosphonates inhibit bone resorption by osteoclasts

Answer 19

:)

Question 20

Estrogen increases production of a decoy molecule that doesnt allow activation of RANK receptor

Answer 20

:0

Question 21

Post-menopausal women predisposed to osteoporosis because loss of…

Answer 21

estrogen - which inhibits osteoclasts (normally), so they go un-leashed

Question 22

Bisphophonate MOA

Answer 22

Bind to sites of bone remodeling

Inhibit osteoclasts by (1)apoptosis and (2)inhibit protein synthesis w/i cell, necessary for function

Question 23

Bisphosphonates are 1st-line, most effective in preventing and treating osteoporosis

Answer 23

:0

Question 24

Alendronate or Risedronate dose, ADR

Answer 24

Bisphosphonates: weekly or monthly PO

Esophagitis, GI upset

Question 25

Selective Estrogen Receptor Modulator (SERM) in osteoporosis

Answer 25

Prevention and treatment only if patient can't tolerate a bisphosphonate or is at risk of breast CA (contra of estrogen)

Question 26

Denosumab MOA

Answer 26

Antibody against RANKL - reduces osteoclast activation and improves BMD

Question 27

Denosumab use

Answer 27

For tx of patient with high fracture risk

Question 28

Teriparatide (Forteo) treats osteoporosis by stimulating bone formation. UNIQUE

Answer 28

All other treatments are anti-resorptive agents

Question 29

Teriparatide MOA

Answer 29

must be given intermittently increases osteoblastic activity expensive

Question 30

Calcitonin Use in Osteoporosis

Answer 30

Treats not prevents inhibits osteoclastic resorption Subcutaneously or intranasal Expensive

Question 31

Thiazide diuretics in hypercalciuria

Answer 31

Reduces urinary calcium excretion

Question 32

Hypercalcemia caused by

Answer 32

hyperparathyroidism and/or cancer | Muscle weakness, lethargy

Question 33

Saline diuresis in hypercalcemia

Answer 33

Frequently dehydrated. Once rehydrated, loop diuretics can be used to increase Ca++ excretion

Question 34

Bisphosphonates in hypercalcemia

Answer 34

Mainstay of treatment. Potent inhibition of osteoclastic bone resorption

Question 35

Calcitonin in hypercalcemia

Answer 35

potentially useful - decreases calcium mobilization out of bone

Question 36

Hypocalcemia causes

Answer 36

hypoparathyroidism, Vit D deficiency, hypomagnesemia

Question 37

Hypocalcemia TX with Calcium (acute)

Answer 37

Calcium gluconate IV for treatment of severe hypocalcemic tetany

Question 38

Hypocalcemia TX with Calcium (chronic)

Answer 38

supplements recommended only if can't be taken in from diet

Question 39

Vitamin D supplements in hypocalcemia

Answer 39

Improves intestinal Ca++ absorption | supresses bone remodelling