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
