Osteoporosis Flashcards
What does osteo mean?
Bones
What does porosis mean?
Pores
What is osteoporosis?
- Higher breakdown of bone in comparison to the formation of new bone which results in porus bones.
- Decrease in bone density resulting in a potential to a fracture
What is the hard external layer of the bone called?
Cortical Bone
What is the soft internal layer of the bone called?
- Spongy or Trabecular Bone
What is the spongy bone or trabecular bone composed of?
It is composed of trabeculae
What is the purpose of the trabeculae?
- Framework of beams that provide structural support to the spongy bone / trabecular bone
What is the cortical bone made of ?
Many osteons
What are in the middle of osteons?
Hollowed spaces called haversion canals which contain the blood supply, andinnervation of the blood cells
What are around the haversian canals?
There are concentric lamellae
What are concentric lamellae composed of?
Organic: Collagen
Inorganic: Calcium phosphate (Hydroxyapatite)
What are in between neighboring lamellae?
Spaces called lacunae
What are inside lacunae?
They contain bone cells called osteocytes
What are the steps of bone remodeling?
1) Bone resorption (Osteoclast)
2) Bone formation (Osteoblasts)
During bone remodeling spongy bone is replaced every ?
3-4 years
During bone remodeling compact bone is replaced every?
10 years
What is bone remodeling dependant on?
- Serum Ca2+ levels
How is Serum Ca2+ levels kept in the normal range?
By a balance between
- Parathyroid hormone (PTH)
- Calcitonin
- Vitamin D
What is the parathyroid hormone produced by?
The parathyroid glands in response to low serum calcium
What do the parathyroid hormones increase?
It increases bone resorption to release calcium into the bloodstream
What is calcitonin produced by?
By the thyroid gland in response to high serum calcium (opposes action of PTH)
What does calcitonin promote?
- It promotes bone formation and decreasing bone resorption
What does vitamin D promote?
- It promotes calcium absorption in the gut (Increasing serum calcium)
- promoting bone formation & decreasing bone resorption
What does the balance between these regulatory factors result in? (PTH, vitamin D, and calcitonin)
- Peak bone mass (usually by age 20-29)
Does peak bone mass occur faster in males or females?
Usually in females
What are factors that determine peak bone mass?
- Genetics
- Nutrition (Vitamin D)
- Strength training
- Hormones (Estrogens & Androgens (Inhibit bone resorption))
What happens when osteoclasts break down bone faster then osteoblasts can rebuild it?
- Lowering of the bone mass
- Eventually into osteoporosis
What is the difference between osteoporosis and Osteomalacia?
- Osteoporosis: has normal cells & mineralization
- Osteomalacia: Lack of mineralization
What are the abnormal findings with osteoporosis?
- Fewer trabeculae in spongy bone
- Thinning of cortical bone
- Widening of haversian canals
What do the bone changes in
- Fewer trabeculae in spongy bone
- Thinning of cortical bone
- Widening of haversian canals
, can cause to a patient?
- Increased risk of fractures (known as fragility / pathologic fractures)
What are the vertebrae, shoulder blades, and ribs consists mainly of what?
Spongy bone
Since the vertebrae, shoulder blades, and ribs consists mainly spongy bone what do risk are they put into?
- Increased risk of fragility fractures
What are the factors that increase bone mass loss and increase risk of osteoporosis?
- Low estrogen levels (after menopause)
- Low serum calcium levels
- Alcohol consumption
- Smoking
- Drugs (Like glucocorticoids which deacrese calcium absorption of the gut through the antagonism of VIT D
- Drugs ( Heparin, L-Thyroxine)
- Physical inactivity (Lack of stress —> Bone deposition deacreses and resorption increases)
- Diseases (Turner syndrome, Klinefelter syndrome, Cushing syndrome, and diabetes mellitus)
What are the two most common types of osteoporosis?
- Postmenopausal osteoporosis
- Senile osteoporosis
What happens in postmenopausal osteoporosis?
- Decreased estrogen levels lead to increased bone resorption
What happens in senile osteoporosis?
- Osteoblasts gradually lose the ability to form bone
- Osteoclasts keep resorbtion going
- Osteoclasts overtakes > osteoblasts
- 8th decade of life
Do people usually have symptoms with osteoporosis?
They dont usually until a fracture occurs
What are the most common types of fractures associated with osteoporosis?
- Vertebral/compressions fractures (occurs when one or more bones in the spine weaken and shatter)
- Femoral neck fractures
- Distal radius fractures
What do vertebral fractures cause?
- Back pain
- height loss
- hunched posture (kyphosis)
Which kinda fractures are associated with postmenopausal osteoporosis?
- Femoral neck
- Distal Radius
How is osteoporosis diagnosed?
Dual-Energy X-Ray absorptiometry (dexa) scan
What does Dual-Energy X-Ray absorptiometry (dexa) scan test?
- Bone density
- Compares an individual’s bone density to that of the normal adult which results in a T-Score
What is a T-Score?
Determines if someone has osteoporosis
T < or equal to -2.5 = osteoporosis
Normal treatment of osteoporosis?
First line drugs
Bisphosphonate drugs
- Alendronate
- Risedronate
——————————————————
During postmenopausal osteoprosis these below:
Denosumab
- Monoclonal Antibody
Raloxifene
- Selective estrogen receptors modulator
Which treatments do we use for advanced osteoporosis?
- Teriparatide (a recombinant PTH)
which increased bone formation - Thiazide diuretic: Hydrochlorothiazide (Boosts Ca2+ retention in kidney, and stimulates osteoblasts differentiation, therefor decreasing mineral bone loss)
