Bone Diseases Flashcards
What is the PTH and calcium relationship?
What is the Vitamin D cycle?
Skin turns sunlight to D3
Liver to 25 0Hd
Kidney to 1.25 0HD (calcitriol)
What is osteoporosis?
A reduction in bone mass due to increased osteoclast activity
What are the symptoms of osteoporosis?
None, until fracture occurs
What are the common locations for osteoporosis related fractures?
Femur, wrist, vertebrae
What are the metabolic/hormone risk factors for osteoporosis?
Hyperparathyroidism
Cushings - Cortisol suppresses osteoblasts
Menopause in women as oestrogen protective
Late menarche
When does bone mass start to reduce?
After 40
What are some other risk factors for osteoporosis?
Genetics
Low/High BMI
What are some drug risk factors for osteoporosis?
SSRIs
Steroids
Chemo
What are the investigations for osteoporosis and what are the values?
DEXA scan.
T <-2.1 is osteoporosis.
T<-1 - 2.1 is osteopenia
What is the conservative management for osteoporosis?
Active lifestyle
Vit D and calcium supplements
What is the drug management for osteoporosis - 2 classes and actions
Increase bone formation - Pulsatile PTH (teriparitide)
Decreasing bone resorption - Deriosiman (RankL inhibitor). Bisphosphonates (alendronic acid, zolendronic acid) inhibits osteoclasts
What would blood tests show for osteoporosis?
Just increased bone resorption, not actual blood tests
What is osteomalacia/Ricketts
Osteomalacia is adults and ricketts kids.
This is a lack of bone mineralisation due to low vitamin D
What is the pathway for osteomalacia/ricketts?
Low vit D = Low Calcium = High PTH = increased bone resorption
Why does osteomalacia lead to osteoporosis and what metabolic disorder does it lead to?
Low vit D = Low Calcium = High PTH = increased bone resorption
Secondary hyperparathyroidism
What are the symptoms of osteomalacia/ricketts?
Bone pain and deformity
Fractures
Myopathy
Growth retardation
What are the causes of osteomalacia/ricketts?
Low vit d due to low sun exposure
Malabsorption
Abnormal vit D metabolism due to liver/kidney disease
What is the treatment for osteomalacia/ricketts?
Vit D supplements
Need the active form if the problem is in the liver of kidneys
What would the urine show of someone with osteomalacia/ricketts?
Low calcium, high phosphate
What would the blood show in someone osteomalacia/ricketts?
Low or normal calcium (secondary hyperparathyroidism)
Raised PTH
Low Vit D
Raised ALP
What is Pagets Disease?
This is disordered bone metabolism with increased osteoclast activity and conpensatory increased osteoblast activity. This forms lots of woven bone
What are the symptoms of Pagets Disease?
Usuall asymptomatic but can cause:
Bone pain
Bone deformities, eg facial bossing
Fractures
Neurovascular problems, eg deafness.
What would investigations into Pagets disease show?
Increased ALP and Calcium
Normal PTH
Increased uptake on a bone scan
