Metabolic Bone Disorders

Question 1

Define Osteopenia- when does this occur?

Answer 1

Decreased bone density or increased radiolucency of bone (darker radiographically)
Occurs when bone reabsorption exceeds bone formation

Question 2

Is osteopenia a precise diagnosis?

Answer 2

NO it is just a descriptive term

Question 3

Osteopenia is the opposite of…

Answer 3

Osteosclerosis

Question 4

What are the major causes of diffuse osteopenia

Answer 4

Osteoporosis
osteomalacia/rickets
hyperparathyroidism (HPT)
Neoplasm (ex lymphoma)

Question 5

Where would we commonly find hyper para-thyroidism?

Answer 5

look to the hands

Question 6

Considering neoplasm for the reason of bone destruction what would (1) a child with osteopenia most likely have and (2) what would an adult with osteopenia most likely have?

Answer 6

Child with osteopenia most likely has leukemia

Adult with osteopenia most like would have multiple myeloma

Question 7

Do see bone density changes where is the best place to look?

Answer 7

Usually you want to look some where other than the spine to find bone density changes

Question 8

What are the 5 bone cells?

Answer 8

Osteoprogenitor
Osteoblast
Osteocyte
Bone Lining Cells
Osteoclasts

Question 9

Where are osteoprogenitor cells formed and what do they develop into?

Answer 9

From marrow stem cells

Develop into osteoblasts

Question 10

What do osteoblasts produce?

When does it decrease in number?

Answer 10

Osteoid = SOFT material
90-95% collagen
Ground substance = mucopolysaccharides
*Osteblasts begin numerous and large in size - but they decrease in size and number at maturity which is about 21 years old

Question 11

OsteoCYTE

• Who do they arise from?
• What is their function?
• What qualities do they have?

Answer 11

Arises from osteoblasts that become entrapped in their own osteoid

• They maintain the integrity of surrounding bone; connected through cannuliculij - they can reabsorb bone
• they are considered a mature bone cell
• both osteoclastic and plastic qualities

Question 12

Which bone cell is considered the mature bone cell?

Answer 12

Osteocyte

Question 13

Osteoclasts

• function?
• Derived from?

Answer 13

Bone resorptive cells

Derived from hematopoietic monocyte linage (macrophages from the same lineage - also have the ability to resorb bone)

Question 14

Osteoprogenitor, osteoblast, osteocyte and bone lining cells all arise from the same linage T/F

Answer 14

True

Question 15

Bone is in a constant state of turn over T/F

Answer 15

True

Question 16

Water makes up ____% of bone weight

Answer 16

20%

Question 17

Organic Matrix/osteoid is made up of ____% of _______ and ____% of ______.

Answer 17

Organic Matrix/osteoid is made up of 30% collagen and 10% mucopolysaccharide.

Question 18

Organic matrix/osteoid make up ____ % of the dry weight of bone.

Answer 18

30%

Question 19

Inorganic materials are minerals they make up ___% of dry weight of bone/

Answer 19

70%

Question 20

Bone quality ratio is comparing

Answer 20

Matrix (30%) : Mineral (70%)

Question 21

Inorganic minerals in bone are

Answer 21

Ca10 (Po4)6OH aka calcium hydroxyapatite

Question 22

Skeletal bone contains ___% of calcium as serum calcium

Answer 22

99%

Question 23

What two mechanisms does bone play in calcium homeostasis?

• percentage of calcium they work with
• which one is more predominate way of maintaining calcium hemostasis?

Answer 23

1) continuous exchange of calcium ions between the bone and ECF (70%)
2) Mediated PREDOMINANTLY by ParaThyroid Hormone and other hormones (30%)

Question 24

If someone is hypocalcemia this stimulates the rebase of Ca++ from______.

Answer 24

Bone

Question 25

If someone is hypercalcemic this produces an influx of Ca++ into _____ form the _____.

Answer 25

Into the bone | From the ECF

Question 26

Where do osteoclasts exist in bone?

Answer 26

On the bone surface in pits known as, HOWSHIP LACUNA

Question 27

Explain the mechanisms of Osteoclasts

Answer 27

Osteoclasts secrete acid to break down bone This unit of acid is hydroxyapatite and collagenase - this will break down osteoid Then they secrete substance to attract and promote osteoblast function

Question 28

What stimulates activity of osteoclasts

Answer 28

``` Parathyroid hormone VitD metabolites Prostaglandin E2 Thyroid hormone Heparin ```

Question 29

What inhibits activity of osteoclasts

Answer 29

calcitonin and estrogen

Question 30

What mineralizes osteoblasts once they produce osteoid/matrix

Answer 30

calcium hydroxyapatite

Question 31

Osteoblast activity is stimulated by

Answer 31

calcitonin

Question 32

Scurvy is a result of what vitamin deficiency

Answer 32

Vitamin C

Question 33

Vitamin C is required for ______ formation

Answer 33

collagen

Question 34

What is the result of scurvy on bone density?

Answer 34

Scurvy will cause you to have osteopenia via osteoporosis

Question 35

List the normal physiological needs for normal bone density requirements

Answer 35

``` Weight bearing exercise normal nervous system function normal GI function (ca++ absorption) Normal liver function (hydroxylations) Normal Renal functions Dietary Ca++ and Phosphate Normal endocrine function (need to have PTH****) ```

Question 36

Why is osteoporosis NOT a bone softening disease

Answer 36

Because in osteoporosis the quality of the bone is normal - it is just the quantity that is not normal - there is not enough cortical or trabecular bone

Question 37

T/F Osteoporosis is the most frequent metabolic bone disease in humans

Answer 37

true

Question 38

______% bone loss before radiographic detectability

Answer 38

30 - 50%

Question 39

Bone loss in the spine is only noticeable at ____% loss because

Answer 39

50% loss because its mostly trabecular

Question 40

Bone loss in extremities is only noticeable at ____% loss

Answer 40

30%

Question 41

What two places does osteoporosis predominate?

Answer 41

Axial Skeleton and proximal long bones