Pth Ca Homeostasis

Front 1

What does serum calcium help maintain?

Back 1

NM transmission, blood coagulation, muscle contraction, cardiac function, cell membrane permeability

Front 2

What form of serum calcium is physiologically active?

Back 2

Free, unbound, ionized calcium

Front 3

What decreases calcium absorption?

Back 3

Age, estrogen decline

Front 4

How is PTH release regulated?

Back 4

Inversely regulated by CaSR, a GPCR that detects Ca levels. Release when hypocalcemia, inhibited with hypercalcemia

Front 5

What are normal levels?

Back 5

8- 10 (14 fatal)

Front 6

What are the three main actions of PTH?

Back 6

1. promotes renal tubular reabsorption of Ca (decreases excretion)
2. Increases resorption of Ca and phosphorus from bone and increases mobilization
3. promotes renal synthesis of 1,25-(OH)2-Vit D active form

Front 7

How does PTH increase resorption of Ca and phosphorus from bone?

Back 7

stimulates RANKL ligand by osteoblasts, acting on RANK promotes osteoclast formation and activity --> both resorption and formation

Front 8

What does excess PTH do versus low pulsatile?

Back 8

resorption vs bone formation

Front 9

What is the major regulator of Ca in the intestines?

Back 9

1,25-(OH)2-Vit D

Front 10

What form of vit D is the mammalian derived product?

Back 10

D3 or cholecalciferol

Front 11

What important concept of the vit D pathway is needed to determine treatment for vit D, Ca, or phosphate issues?

Back 11

The mechanism for treatment depends on the location of problem in pathway, ie if renal failure, give 1,25-(OH)2 D3 and not anything else cause cant convert

Front 12

Vit D3 is produced in the skin from ___ under influence of ___?

Back 12

cholesterol; UV light

Front 13

What is the pathway?

Back 13

vit D -> in skin --> D3 --> stored in fat --> liver --> calcifediol (most abundant) --> kidney --> calcitriol (active)

Front 14

What promotes/inhibits production of calcitriol?

Back 14

PTH, low levels of Ca or phosphate; inhibited by itself

Front 15

What are the actions of calcitriol?

Back 15

induces absorption of Ca and phosphate in intestines; induces RANKL; decreases excretion. Mostly same as PTH

Front 16

Where is calcitonin produced and half-life?

Back 16

parafollicular C cells of thyroid; 10 min

Front 17

What is secretion promoted by?

Back 17

Hypercalcemia

Front 18

What are the two main actions of calcitonin?

Back 18

increases excretion and inhibits bone resorption by osteoclastic and osteocytic cells

Front 19

Does calcitonin have Ca resorption effects in the intestine?

Back 19

no

Front 20

What is the most common metabolic bone disease and 2 causes of elderly morbidity?

Back 20

osteoporosis; "Dowagers hump" loss of height due to spine collapse, hip fractures

Front 21

When is estrogen replacement therapy used for osteoporosis and what caveat should be remembered?

Back 21

postmenopausal; it does not reverse bone loss, just prevent it; increases breast cancer and heart disease

Front 22

What SERM reduces new vertebral fractures by 30% and 50% with no previous fractures?

Back 22

Raloxifene

Front 23

What tissues do SERMs exhibit activity at?

Back 23

estrogen agonist in bone; estrogen antagonist at breast and uterus

Front 24

What is a contraindication for bisphosphonates?

Back 24

ulcerative esophagitis

Front 25

Which drug is also used in Paget's disease and can improve bone mass in established osteoporosis?

Back 25

bisphosphonates

Front 26

Which osteoporosis drug is poorly absorbed in the GI?

Back 26

bisphosphonates

Front 27

How does sodium fluoride work?

Back 27

Instead of decreasing bone resorption, it increases osteoblast prolif and formation.

Front 28

What does excess fluoride cause?

Back 28

bone fragility

Front 29

Which drug is a PTH analog and is administered intermittently to those who can't tolerate dronates?

Back 29

teriparatide

Front 30

Which drugs can cause drug induced osteopenia?

Back 30

anticonvulsants, chronic glucocorticoids, and alcoholism

Front 31

What would you see in a patient with pseudohypoparathyroidism?

Back 31

end organ insensitivity to PTH, normal to high levels of PTH

Front 32

What two calcium supplements are used for hypocalcemia?

Back 32

oral Ca carbonate and IV Ca gluconate (infants or ER or severe)

Front 33

What is the common cause and treatment of primary hyperparathryoidism?

Back 33

parathyroid adenomas; surgical removal

Front 34

What drug stimulates CaSR and causes a decrease in PTH?

Back 34

Cinacalcet

Front 35

What precautions should be heeded with cinacalcet

Back 35

may cause hypocalcemia, do not use with dronates, etc; be cautious of
CYP3A4 inhibitors

Front 36

Most common cause of hypercalcemia

Back 36

Paget's disease; slow virus infection

Front 37

Paget's disease causes excessive bone resorption and disorganized remodeling leading to?

Back 37

nerve compression; increased bone vascularization, abnormal bone structure

Front 38

Treatment of choice for severe Paget's disease and differences between types

Back 38

Calcitonin; salmon-derived has longer half life and greater potency, admin through nasal spray, sc or im; human no refractory, admin im or sc

Front 39

2 types of bisphosphonates approved for Paget's disease

Back 39

Etidronate (older), Pamidronate (newer)

Front 40

Cytotoxic antibody treatment used if unresponsive to bisphosphonates and calcitonin?

Back 40

Plicamycin (mithramycin)

Front 41

What is used in emergency hypercalcemia associated with malignancy?

Back 41

plicamycin (mithramycin)

Front 42

What are other emergency treatments for hypercalcemia?

Back 42

saline infusion with or w/o loop diuretics, calcitonin, prednisone or other steroids,