parathyroid

Question 1

how much of the skeleton is cortical bone?

Answer 1

80%

Question 2

where is cortical bone found?

Answer 2

int he shafts of long bone

Question 3

what does cortical bone provide us with?

Answer 3

mechanical support and protective functions for the hematopoietic system.

Question 4

where is trabecular bone

Answer 4

at the ends of long bones, ribs, vertebral bodies, pelvic.

Question 5

what does trabecular bone do?

Answer 5

serves the metabolic functions of the skeleton.

Question 6

where do osteoblasts come from? what do they do?

Answer 6

mesenchymal system. bone forming cell. responsible for making osteoid and its subsequent mineralization

Question 7

where do clasts come from and what do they do>

Answer 7

hematopoietic system and are a modified macro. they are responsible for break down.

Question 8

osteocytes?

Answer 8

they are osteoblasts that have been caught in the mineralized matrix. play a role in mobilizing minerals.

Question 9

OPG

Answer 9

osteoprotegerin. when expressed inhibits physiological and pathological breakdown of bone.

Question 10

RANKL and RANK

Answer 10

involved in the osteoclastic activation

Question 11

bone formation markers

Answer 11

alk phos and osteocalcin

Question 12

bone breakdown markers

Answer 12

TRAP (serum), NTx/CTx (serum and urine)

Question 13

What controls the release of PTH

Answer 13

serum calcium levels. when low PTH is secreted.

Question 14

what does PTH do?

Answer 14

defends against hypocalcemia. stimulation of bone resorption by clasts. renal reabsorption of Ca and Mg. inhibition of reabsorption of Ph and Bicarb. stimulation of Vitamin D production.

Question 15

is the activation of osteoclasts by PTH direct or indirect?

Answer 15

it is indirect, there is no PTH receptor on the clast. just on the blasts.

Question 16

does PTH enhance the intestinal reabsorption of Ca2?

Answer 16

indirectly through activation of Vitamin D.

Question 17

what percentage of calcium is ionized

Answer 17

50

Question 18

what percentage of calcium is protein bound

Answer 18

40.

Question 19

what percentage of ca is complexed

Answer 19

10

Question 20

what effect does acidosis have on the calcium level?

Answer 20

increases it because it releases it from albumin binding.

Question 21

what is the correction formula for calcium

Answer 21

Cca = Mca + 0.8 (4 - Malb)

Question 22

where is ca absorbed

Answer 22

in the intestines, duodenum and jejunum.

Question 23

what is the main determinant of intestinal absorption

Answer 23

activated Vitamin D

Question 24

what affects the absorption of Ca

Answer 24

ceoliac, bypass, malabsorption, low Vit D.

Question 25

where are the main sources of ca loss?

Answer 25

urine and feces.

Question 26

what enhances reabsorption of ca in the kidney

Answer 26

PTH, PRPrP, alkalosis, thiazides, reabsorption of sodium

Question 27

what decreases the reabsorption of Ca

Answer 27

acidosis, loops, saline diuresis and low PTH

Question 28

what increases the retention of phos

Answer 28

low PTH/hypoPT, low calcium. hypophos

Question 29

who gets dietary phosphate deficiency?

Answer 29

RARE. alcoholics, and people taking large amounts of aluminum containing antacids.

Question 30

where do we get Mg from

Answer 30

green vegetables and meats. 40% is absorbed from the intestine.

Question 31

what can cause hypoMg

Answer 31

loop diuretics and cisplatin.

Question 32

what are the most common causes of hypercalcemia

Answer 32

hyperparaT, or malignancy.

Question 33

what is the first step in a calcium workup?

Answer 33

PTH levels.

Question 34

what is the most common source of hyerPTH

Answer 34

solitary adenoma 80%

Question 35

how common is parathyroid carcinoma

Answer 35

extremely rare.

Question 36

what is the most common presentation of hypercalcemia when looking at Ca and PTH

Answer 36

low PTH, high calcium

Question 37

what is suggestive of familial hypocalciuric hypercalcemia

Answer 37

when the calcium clearance is less than 0.01.

Question 38

what is the causes of FHH

Answer 38

lack of the calcium sensor function

Question 39

what is milk alkali syndrome

Answer 39

consumption of large amounts of ca in the context of an alkali substance -TUMS.

Question 40

treatment for mild hyperCa

Answer 40

advise patient to increase fluid intake and moderate Ca diet. discontinue meds that cause high ca

Question 41

treatment for moderate hyperCa.

Answer 41

often requires direct measures to lower the calcium in the blood stream.

Question 42

what medications cause retention of calcium

Answer 42

thiazides and lithium.

Question 43

treatment for severe hyperCa

Answer 43

needs immediate treat. FLUIDS. bisphosphonates, calcitonin, corticosteroids, and dialysis

Question 44

why give fluids in severe hyper Ca

Answer 44

because hypercal causes dehydration. loops can be given to increase the calcium excretion. must be careful though.

Question 45

what is the corner stone treatment?

Answer 45

bisphosphonates. bind calcium immediately lowering the levels in most patients. this is the mainstay treatment.

Question 46

what does calcitonin do for hypercalcemia

Answer 46

mild, yet rapid effect for lowering the serum calcium. increases the renal excretion.

Question 47

what is the downfall of calcitonin

Answer 47

within 2-3 days there is down regulation and tachyphalaxis

Question 48

how do corticosteroids work for hyperCa and which diseases do they work the best on?

Answer 48

they will decrease the production of VIT D. work best in vitamin D intox, granulomatous and malignancy.

Question 49

what are the common causes of hypoPT

Answer 49

agenesis, surgical destruction, altered production of PTH, pseudohypoPT.

Question 50

what is low vitamin D classically associated with?

Answer 50

osteomalacia and rickets.

Question 51

how does low vitamin D present

Answer 51

hypocalcemia and hypophosphatemia.

Question 52

osteoporosis?

Answer 52

caused by increases in the rate of bone remodeling with more osteoclastic activity than osteoblastic. increase in the bone fragility and increase risk of fractures.

Question 53

bisphosphonates

Answer 53

reduce osteoclastic bone resorption. increase bone mineral density and decrease bone turnover markers. they also reduce fracture risk.

Question 54

side effects of bisphosphonates

Answer 54

GI irritation and esophageal.

Question 55

SERMs

Answer 55

estrogen like compounds that decrease bone resorption.

Question 56

SERMs side effects

Answer 56

hot flashes and DVT

Question 57

calcitonin

Answer 57

unique effect on the vertebral fractures as an analgesic. given through the nostrils as an inhalant. inhibits osteoclast resorption.

Question 58

side effects of calcitonin

Answer 58

rhinitis. minimal

Question 59

triparatide

Answer 59

PTH analog. unique anabolic agent. given in short subcutaneous bursts has the ability to only activate blasts and increase BMD and decrease fractures. only given as alternative. only the first part of the molecule.

Question 60

side effects of triparatide

Answer 60

transient hyperCa. also has a black box warning for osteosarcoma.

Question 61

denosumab

Answer 61

antibody that works as a RANK ligand inhibitor. antiresorptive agent that works on osteoclasts.

Question 62

pagets disease

Answer 62

increased alk phos with a increased bone metabolism. results in enlarged bone. presents as localized bone pain. initiated by osteoclast bone reposition and then a compensatory bone formation resulting in a disorganized mosaic. look to the pelvis, spine, femur, tibia, skull. formation and resorption markers are typically elevated. bone deformation, pain, hearing loss, fractures, osteosarcoma.