Kinder, bone mineral homeostasis part I Flashcards

1
Q

what minerals are used for bone homeostasis

A

Ca

phosphate

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2
Q

what hormones are used for bone homeostasis

A

teriparatide (forteo)

calcintonin (fortical)

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3
Q

what are the drugs we have that are vit D, metabolites and analogs

A

cholecalciferol (Vit D3)
ergocalciferol (Vit D2)
calcitriol

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4
Q

drug that is selective estrogen R modulator

A

raloxifene (Evista)

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5
Q

what bisphosphonate do we use

A

alendronate (fosamax)

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6
Q

where is most cortical bone

A

appendicular or peripheral bone

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7
Q

where is trabecular bone

A

acial or central (spine and pelvis)

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8
Q

what regulate osteoclast production

A

osteoblast derived cyrokines

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9
Q

What is RANK

A

R for NK-kbeta that is an osteoclast protein required for osteoclastic bone resorption

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10
Q

osteopblasts produce what to keep osteoclast under regulation

A

osteoprotegerin which acts as a decoy ligand for RANKL

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11
Q

when is OPG suppressed

A

increased bone resorption

e.g. estrogen deprivation

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12
Q

how long does remodeling of one take

A

6 mo

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13
Q

where is Ca absorbed

A

duodenum and upper jejunum

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14
Q

what is absorbed more, Ca or PO4

A

PO4

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15
Q

where is filtered Ca resorbed

A

kidney

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16
Q

extracell Ca and PO4 levels

A

Ca 8.5-10.4

PO4 2.5-4.5

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17
Q

how does PTH change Ca and PO4 levels

A

increased serum Ca and decreased serum PO4

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18
Q

how does PTH increase osteoclasts

A

induces osteoblasts to secrete RANKL

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19
Q

PTH inhibits production of what from osteocytes

A

sclerostin which blocks osteoblast proliferation

20
Q

PTH affect on kidney

A

PTH increases tubular reabsorption of Ca and inhibits reabsorption of PO4

21
Q

PTH increases excretion of what

A

amino acids, bicarb, Na, Cl, and sulfate

22
Q

Ca changes PTH how

A

decrease PTH production

23
Q

what is teriparatide

A

synthetic recombinant human PTH

24
Q

MOA teriparatide

A

continuous administration of PTH caues bone demineralization and osteopenia
intermittent PTH promotes bone growth

25
Q

therapeutic use teriparatide

A

women with Hx osteoporosis who have multiple risk factors for fracture, or who have failed other therapy
men with primary hypogonadal osteoporosis

26
Q

adverse effects teriparatide

A

orthostatic HTN, hyper Ca, dizziness, nausea, hyperuricemia, angina

27
Q

CI teriparatide

A

those at increased risk osteosarcoma, like Pagets or elevated alkaline phosphatase levels, open epiphyses or prior radiation therapy of skeleton

28
Q

How is Vit D3 formed to active 1,25 dihydroxy vit D3

A

ultraviolet light on skin

then hydrozylation in liver and then in kidney

29
Q

how does calicitriol increase bone turnover

A

promotes recruitment of soteoclast precursor cells to resorption sites
promotes development of mature osteoclasts
induce synthesis of several proteins that regulate bone mineralization process such as RANK ligand and osteocalcin

30
Q

how do Vit D analogs work

A

increase intestinal absorption of Ca and PO4 as well as bone turnover

31
Q

therapeutic use of vit D analogs

A

prophylaxis and cure of nutrional rickets
Tx metabolic ricketts and osteomalacia
Tx hypoPTH
prevention and Tx osteoporosis

32
Q

what do ergocalcigerol or cholecalciferol require

A

metaboilc conversion in liver and kidney

33
Q

what to give patient with liver disease and rickets or osteomalacia

A

25, hydroxyvit D because does not require hepatic hydroxylation

34
Q

why is calcitriol used in patients with kidney disease

A

most rapid onset

35
Q

what to watch when patient is on calcitriol

A

hypercalcemia

36
Q

adverse effects to Vit D analogs

A

hyperCa, sometimes hyperPO4, nausea, vomiting, constipation

arrhythmias and pancreatitis

37
Q

how does FGF-23 affect Ca and PO4 regulation

A

inhibits 1,25 OHvit D production and PO4 reabsorption in kidney

38
Q

how does PTH change intestinal Ca and PO4

A

increased Ca and PO4 absorption

increased 1,25 OH production

39
Q

how does PTH affect kidney excretion of minerals

A

dec Ca excretion

increased PO4

40
Q

Vit D affects on intestine

A

increased Ca and PO4 absorption

41
Q

Vit D affects on kidney

A

Ca and PO4 excretion

42
Q

FGF23 affects on intestine

A

dec Ca and PO4 absorption

43
Q

FGF23 affects on kidney

A

increased PO4 excretion

44
Q

PTH affects on bone

A

Ca and PO4 resorption increased by high doses, low doses may increase bone formation

45
Q

Vit D affects on bone

A

increased Ca and PO4 resorption by 1,25 OH Vit D,

46
Q

FGF23 affects on bone

A

dec mineralization from hypoPO4

47
Q

serum levels from:

  • PTH
  • Vit D
  • FGF23
A

PTH: increased serum Ca decreased serum PO4
VitD: increased serum Ca and PO4
FGF23: decreased serum PO4