Week 3 Flashcards
Modifiable risk factors of osteoporosis
○ Nutrition: calcium/ vit D deficiency, malabsorptive diseases, anorexia nervosa
○ Lack of physical activity
○ Smoking
○ Excess alcohol
○ Medication use: Anticonvulsants, aromatase inhibitors, Glucocorticoids, GnRH agonists/antagonists, Heparin
○ Effects of other disease: cancer, Hyperparathyroidism, Hyperthyroidism, Hypogonadism, inflammatory disease, liver disease, chronic kidney disease
Non-modifiable risk factors of osteoporosis
○ Race: White/Asian ○ Gender ○ Age ○ Postmenopausal ○ Small body/bone size ○ Hereditary disposition ○ Inherited bone disorders: Osteogenesis imperfecta, Osteoporosis psuedoglioma syndrome, Hypophosphatasia ○ Inherited non-skeletal disorders with predisposition to low bone density: Cystic fibrosis, Galactosemia, Muscular dystrophy, Neurofibromatosis, Storage disease, Ehlers danlos syndrome, Marfan syndrome ○ Idiopathic- Spontaneous occurrence
Metabolic changes that occur in bone with osteoporosis
bone remodeling with balanced formation and resorption becomes uncoupled, leading to bone loss and increased risk of fracture.
DEXA scan
- how it works
- how to interpret results
- t vs z
- machine produces two X-ray beams: One high energy and the other is low energy. The machine measures the amount of X-rays that pass through the bone from each beam. Based on the difference between the two beams, your doctor can measure your bone density.
- T-score of -1.0 or above = normal bone density; between -1.0 and -2.5 = low bone density, or osteopenia; -2.5 or lower = osteoporosis
- Z score: compares your bone density to a normal score for a person of your same age and body size.
Osteoporosis vs low bone mass (osteopenia)
- how are they different
- how are they connected
- Osteoporosis: bone-thinning disease that causes your bones to become thin and weak and increases the risk of breaking a bone. A broken bone may occur from a minor event such as a fall from a standing height.
- Osteopenia: is a condition not considered a disease.
A person may have low bone mass for a lifetime and never develop osteoporosis.
-If patient has low bone mass and continues to lose bone density over time, they have increased risk of developing osteoporosis.
Frax score
- what is it?
- why is it used?
- factors looked at
- fracture risk or an estimate of the chance of breaking a bone in the next ten years.
- help to identify people who have a greater chance of breaking a bone as well as people who might benefit from taking an osteoporosis medicine.
- age; smoking: family history of hip fracture; glucocorticoid use (eg, Prednisone); arthritis; femoral neck bone mineral density
Risedronate
- how does it work
- important facts
- bisphosphonate: inhibits bone resorption by binding to hydroxyapatite (part of the mineral matrix of bone) leading to an indirect increase in bone mineral density.
- must be taken on empty stomach due to poor absorption
Secondary causes of osteoporosis
- Disease
- how its caused
- how to check for it
- bone loss due to another disease.
- Hyperparathyroidism: increased activity of the parathyroid glands; causes increase in osteoclast activity, elevated serum PTH
- Hyperthyroidism: an excessive secretion of the thyroid glands, increase metabolic activity and overstimulates parathyroid
- Vit D deficiency: not enough Vit D- body cannot absorb calcium; draw serum vit D 25 OH
- Chronic kidney problem (hypercacliuria)- kidneys spilling out calcium in urine
- Estrogen deficiency: ?
- Diabetes: ?
- Hypercortisolism: ?
PTH and bone remodeling
- will increase osteoclast activity to cause increase in serum levels of calcium
- increase RANK-L; also stimulates growth hormone (increases IGF-helps proliferation of osteoblast unless there is excess then promotes osteoclast differentiation)
Teriparatide
- recombinant formulation of PTH
- stimulates osteoblast function and differentiation
- increase GI and renal tubule Ca absorption,
Kinds of hip fractures
-name and where located
- Intracapsular Fractures: break occurs below the ball or in the neck of the femur
- Intertrochanteric Fractures: break occurs between the greater trochanter and lesser trochanter
- Subtrochanteric Fractures: break occurs below the lesser trochanter or further down the femur
Indication for ORIF of hip
for serious fractures where the bone is significantly displaced or articular joint surfaces are disrupted. It is also indicated where the bone would not heal correctly without surgery, or where closed reduction has failed.
Relationship between calcium and vitamin D
-dihydroxyvitamin D: active hormonal form of vitamin D that optimizes calcium and phosphorus absorption, inhibits PTH synthesis
Clinical presentation of patient with SMA type 1
- between 3 and 6 months of age
- severe, progressive muscle weakness and flaccid or reduced muscle tone
- poor suck ability, reduced swallowing, and respiratory failure
Mechanism of areflexia in lower motor neuron diseases
Alpha motor neuron cell bodies in anterior gray horn of spinal cord die, leading to the inability to contract muscle during reflex testing
