osteoporosis Flashcards
What 3 cells maintain bone homeostasis?
Osteoclasts, osteoblasts, osteocytes
What is the role of osteoclasts?
Breaks down bones and releases Ca from bone into blood
What is the role of osteoblasts?
Builds bones
What is the role of osteocytes
Keeps the remodeling of bones in balance so the microstructure is preserved. Keeps bones in equilibrium so you don’t have 1 cell working faster than the other
Apart from the osteo cells, what else regulates bones?
Sex hormones and parathyroid hormone-activated vit D
What do you check to diagnose osteoporosis, and how do you check that?
Check bone mineral density using dual-energy x-ray absorptiometry
What part of the body is bone mineral density measured? (3)
Lumbar area (spine), femoral neck (upper leg/thigh bone) and total hip (hip bone)
Define T-score
It is the standard deviation of a healthy bone mineral density vs an unhealthy patient of the same gender/ethnicity
What is the relationship between good health and T-score?
Inversely proportional, the higher the T-score, the lower the health
What does it mean when you have a T-score of -1 to -2.5?
Means you have osteopenia, which is a warning sign that you will hit osteoporosis, but it isn’t the diagnosis yet
Which of these is NOT a risk factor for osteoporosis?
A. Aging
B. Family history
C. Low BMI, low physical acitvity
D. Smoking/alcohol
E. Fractures
E - that is a consequence of osteoporosis, not a risk factor
Which of these is NOT a risk factor for osteoporosis?
A. Low vit D and low Ca intake
B. Weaker bones
C. Drugs
B - that is a consequence of osteoporosis, not a risk factor
Which of these is NOT a drug that induces osteoporosis?
A. PPI
B. SSRI
C. SGLT2 inhibitors
D. Gonadotropin-releasing hormone (GnRH)
E. Antiepileptic drugs
C
Anastrozole, letrozole, exemestane are drugs that induces osteoporosis. What drug class do they belong to?
Aromatase inhibitors
Goserelin and nafarelin are drugs that induce osteoporosis. What drug class do they belong to?
GnRH agonists
MOA of aromatase inhibitors
Prevents conversion of androgen to E, leading to lower E levels, leading to higher bone loss
How do GnRH agonists induce osteoporosis?
Long-term use suppresses ovaries/testes from making sex hormones, leading to weaker bones and bone mineral density
How do glucocorticoids directly affect the bone?
Reduces osteoblast and increases osteoclast activity
Which of these if NOT an indirect impact of glucocorticoids on the bone?
A. Reduce Ca absorption from blood
B. Suppress growth hormone
C. CHange sex hormone levels
D. Change vit D activation
E. Suppresses osteoblast activity
E - that is a DIRECT impact, not indirect
MOA of how PPI impacts bone density
Ca is absorbed by being dissolved. Ca is best dissolved in lower pH. PPI decreases acid secretion, thereby increasing pH, and inhibiting Ca from being dissolved. Hence, there is less absorption of pH
Thyroxine, tetracycline, quinolone, bisphosphonates.
What impact do these drugs have on Ca?
They reduce Ca absorption from the gut
If thyroxine, tetracycline, quinolone and bisphosphonates reduce Ca, can pxs take them with Ca supplements if they contradict each other?
Pxs can take both but needs to be 2 hours apart
Why is it important to maintain vit D to maintain bone help?
Because Vit D, after being converted into its metabolites by kidney, it promotes Ca absorption and assists with mineralisation of bones by interacting with the parathyroid hormone
How long do you need to wait to take vit D supplements after testing 25-hydroxyvitamin D levels? Why?
3 months. Because it takes that long for vit D to reach steady state
What is the target level for vit D in osteoporosis?
75nmol/L or higher
What is the difference between cholecalciferol and calcitriol?
Cholecalciferol - D3 - increases bone mineral density and is inactive
Calcitriol - D - reduced rate of bone mineral loss and is the active form
When is the best time to take Ca? Why?
In the evening because there is more bone loss at night
When is the best time to take D?
Any time
Which of these drugs is NOT used for osteoporosis?
A. Bisphosphonates
B. PPI
C. Denosumab
D. Teriparatide
E. Hormone replacement therapy (HRT)
B - PPIs actually make osteoporosis worse
Which drug is the first line drug for postmenopausal osteoporosis?
Bisphosphonates
MOA of bisphosphonates
Inhibit osteoclasts
What drug class do these belong to?
Alendronate, risendronate
Bisphosphonates
What drug class does zoledronic acid IV infusion belong to?
Bisphosphonates
When would denosumab be considered for tx?
When px isn’t responding to bisphosphonates
What does the suffix -mab refer to?
Monoclonal antibodies
What is RANKL and RANK?
RANKL is a ligand that is secreted by osteoblasts when there is enough regeneration of bones. RANKL then binds to RANK that is already bound to osteoclasts in order to stimulate it and keep balance
MOA of denosumab
Inhibits RANKL to stop them from binding to RANK, hence inhibiting the stimulation of osteoclasts
How often is denosumab injected?
Every 6 months
Why should pxs on denosumab and bisphosphonates have any dental procedures before initiating therapy?
To avoid osteonecrosis of the jaw. A side effect of the drugs is the exposure of the jaw bone which leads to the death of blood vessels
MOA of raloxifene
E agonist on bone mass and lipids, however it is an E antagonist on other E-receptive tissues like breast and endometrium
Which condition is raloxifene suited for?
Post-menopausal osteoporosis, especially younger post-menopausal women with spine osteoporosis. Also good for women with a higher risk of breast cancer
Relationship between raloxifene and VTE/blockage of veins in legs
Raloxifene increases risk of VTE
Relationship between raloxifene and breast cancer
Raloxifene reduces risk of breast cancer
What is teriparatide
Synthetic form of human parathyroid hormone
MOA of teriparatide
Promote bone formation and increase bone mineral density
Difference between teriparatide and other osteoporosis drugs
Other drugs inhibit bone resorption, teriparatide is the only one that promotes bone formation
True or false?
Teriparatide is the first-line treatment for postmenopausal women and men
False
Teriparatide is the second line tx when pxs can’t tolerated bisphosphonates and denosumab
Why can pxs only use teriparatide for a maximum of 18 months?
To avoid the potential risk of osteosarcoma (type of bone cancer)
