2.4 osteoporosis Flashcards
What is the WHO criteria for osteoporosis?
BMD T score >-2.5
what is the difference between osteoporosis and osteomalacia?
Osteoporosis occurs when the bone matrix is normally mineralised but there is less bone
Osteomalacia is when there is insufficient calcium and phosphate to mineralise newly formed osteoid leading to bone being softer and more liable to bend and deform
How is osteoporosis diagnosed?
In relation to the degree to which bone mineral density is reduced
T score: SD away from young normal mean
Z score: SD away from aged matched mean
T
where do they measure BMD from?
Spine (L1-4 or 2-4) - trabecular bone and useful for monitoring
Hip - cortical bone
What are the advantages and limitations of BMD?
Ad: quick and easy, minimal radiation exposure, widely used in clinical trials
Dis: mineral content across a specific area not taking depth into consideration, does not provide full assessment of bone strength, variation between instruments
What is the FRAX tool?
tool that takes into account clinical risk factors as well as BMD at femoral neck giving a 10 year probability of a fracture occuring
What occurs with the cells in osteoporosis?
There is an increase in osteoclast activity and the osteoblasts do not have enough time to lay down new bone
What are the preventative strategies for osteoporosis?
Calcium intake Exercise Avoid smoking and excessive alcohol Weight bearing exercise Vitamin D
What do effective treatments for osteoporosis need to do?
Increase bone density and reduce fracture rates
How do bisphosphonates work?
They go into the bone and stay there and when the osteoclasts are trying to dig the herniation pit they will take up the bisphosphonates and undergo apoptosis
What are the SE of bisphosphonates
Osteonecrosis of the jaw
What is the RANKL inhibitor and how does it work?
Denosumab
Inhibits osteoclast formation, function and survival
What is SERM and give an example
Selective oestrogen recptor modulator. Acts on estrogen receptors in the bone and not breast tissue
Raloxifene
How does parathyroid hormone work in osteoporosis and what is the drug called?
Teriparatide
Works by increasing serum calcium by increasing bone resorption. With intermittent exposure it activated osteoblasts more than osteoclasts
What drugs are used in post menopausal osteoporosis?
Bisphosphonates
Denosumab
SERM
2nd line: strontium and parathyroid hormone
