Osteoporosis Flashcards
what is bone remodelling?
where old bone is replaced by new bone
bone is an active tissue
what is bone remodelling controlled by?
osteoclasts and osteoblasts and osteocytes
what is bone resorption?
destruction of bone tissues leading to bone loss
-its where osteoclasts form cavities on bone surfaces
what is bone deposition?
-osteoblasts lay down new bone matrix
so formation of new bone
what is bone mineral density (BMD)?
-amount of minerals especially phosphorus and calcium in a bone volume
how does osteoporosis develop?
develops when bone resorption exceeds bone formation
-so when bone destruction is more than new bone formation
WHO definition for osteoporosis?
Bone mineral density above 2.5
AND
T-score of -2.5 or less
How is osteoporosis assessed?
Dual-energy X ray absorptiometry (DXA or DEXA)
-measures amount of bone at thoracolumbar spine, forearm, and hip
-measures bone mineral density
what is T-score?
compares patients bone mineral density to a healthy young adult
-osteoporosis = T-score = above 2.5
WHO CLASSIFICATION OF OSTEOPOROSIS
Normal = T-score = 1
Osteopaenia = T-score = -1 to -2.5
Osteoporosis = T-score = below -2.5
Severe osteopororsis = above -2.5
WHO CLASSIFICATION OF OSTEOPOROSIS
Normal = T-score = 1
Osteopaenia = T-score = -1 to -2.5
Osteoporosis = T-score = less than -2.5
Severe osteopororsis = above -2.5
the more negative score, the more severe osteoporosis
how is vitamin D converted to calcitriol?
Vitamin D3 is metabolised into (25-hydroxycholecalciferol) in liver.
then this is converted into CALCITRIOL known as (1,25-dihydroxycholecalciferol) in kidneys.
explain epidemiology of osteoporosis?
-High in white post-menopausal women
-white and asian women have equal risk
-Affects 1 in 3 women and 1 in 12 men in UK
-53% patients lose independence after hip fractures
-reduced quality of life and low self esteem from pain
what are the risk factors of osteoporosis?
Modifiable : smoking, excessive alcohol, low exercise, low calcium intake, low vit D
Non-modifiable : genetics, diabetes, rheumatoid arthritis, chronic liver disease
what are the primary causes of osteoporosis?
Primary causes:
-Female gender- reduced oestrogen levels so more bone loss. oestrogen plays important role in bone formation
-male gender - men have high bone mineral density so slower loss of BMD, fracture risk is less in men. men have shorter life expectancy.
-AGE - bone loss increases as age increases, low calcium and vit D intake from diet or sun. calcium and vit D important in bone health.