Rheumatology - Bone Diseases Flashcards
What is arthritis
inflammation of the joints
What is arthrosis
non-inflammatory joint disease
What is arthralgia
joint pain
What is bone
mineralized connective tissue
What are the features of bone
load bearing
dynamic
self repairing
calcium store
What does the formation of bone require
correct amount of calcium, phosphate and vitamin D
How does bone act as a store for calcium
exchangeable calcium can move from the bone into the ECF
calcium can be lost through the gut and urine
calcium in the blood must be at a precise level for nerve and muscle function
What hormone helps promote the correct concentration of calcium
parathyroid hormone
What happens if there is low dietary calcium
can result in plasma calcium falling, this causes PTH to increase activating vitamin D production and decrease loss of calcium in the kidney and will promote bone resorption and the calcium will be absorbed into the ECF restoring plasma levels
What are the functions of parathyroid hormone
maintains serum calcium level
raised if calcium levels fall
increases calcium release from bone
reduces renal calcium excretion
What are conditions that can effect parathyroid hormone
hypoparathyroidism
hyperparathyroidism
What is the result of hypoparathyroidism
low serum calcium
What are the types of hyperparathyroidism
primary
secondary
What is primary hyperparathyroidism
gland dysfunction - tumor
high serum calcium results as there is inappropriate activation of osteoclasts
What is secondary hyperparathyroidism
it is caused by low serum calcium which activates the PTH which activates osteoclasts but appropriately to maintain serum calcium level
What does hyperparathyroidism result in
increased bone resorption
can see this on radiographs as radiolucencies and reabsorption
How does vitamin D go from diet to the gut
it is absorbed by the diet and sent to the blood and processed by the livers and kidneys to produce 1,25-dihydroxycolecalciferol which is the active version necessary for ca gut absorbtion
What are issues that can result in vitamin D problems
low sunlight exposure
poor GI absorption
drug interactions
Who are at risk of low sunlight exposure
housebound
dark skinned in northern countries (those with melanin absorb sunlight through skin less efficiently)
How can someone have poor GI absorption of vitamin d
poor nutrition
small intestine disease resulting in malabsorption
What drug interactions can cause vitamin d problems
antiepileptics
carbamazepine
phenytoin
What is osteomalacia
poorly mineralized osteoid matrix (bone is formed normally but it is not mineralized properly)
poorly mineralized cartilage growth plate
What is osteoporosis
loss of mineral and matrix (less matrix so correct bone mass it not achieved but matrix that is present is normally mineralized)
reduced bone mass
What is osteomalacia that occurs during bone formation called
rickets
What is rickets and osteomalacia related to
calcium deficiency
serum calcium preserved at expense of bone
What are the bone effects of osteomalacia
bones bend under pressure - bow legs
vertebral compression in adults causing pain in nerves effecting lower limbs
bones ache to touch
What are the hypocalcemia effects seen in osteomalacia
muscle weakness
trosseau and Chvostek signs positive
carpal muscle spasm
facial twitching from VII tapping
What is the serum calcium compared to normal in osteomalacia
decreased
What is the serum phosphate compared to normal in osteomalacia
decreased
What is the alkaline phosphate compared to normal in osteomalacia
very high
What is the plasma creatine compared to normal in osteomalacia
increased if renal cause
What is the plasma parathyoird hormone compared to normal in osteomalacia
increased if secondary hyperparathyroidism
What is the management of osteomalacia
correct the cause if there is malnutrition and control GI disease
sunlight exposure - 30 mins x 5
dietary vitamin D - easiest way
What is osteoporosis defined as
reduced quantity in normally mineralized bone
What is osteoporosis related to
age
inevitable
What are osteoporosis risk factors
age female sex endocrine genetic patient factors medical drug use
What are the endocrine risk factors for OP
ostestrogen and testosterone deficiency
cushings syndromes
What are the genetic risks for OP
family history
race - caucasian & asian women
early menopause
What are the patient factor risks for OP
inactivity
smoking
excess alcohol use
poor dietary calcium
What are the medical drugs use risk factors for OP
steroids
anti epileptics as they can effect calcium metabolism
What is the peak bone mass at
age 24-35
Why are women more at risk of OP
men have higher peak bone mass
estrogen withdrawal increases (menopause)bone mass loss rate in women
less exercise in women (not really anymore)
Why is having a higher bone mass reducing risk of OP
the OP clinical effects are not based on changes relative to bone mass but the absolute peak bone mass
What are the effects of OP
increased bone fracture risk esp in long bones such as the femur
What are the effects of OP on the vertebrae
see height loss because of the bending forward of the spine
kyphosis and scoliosis
nerve root compression - back pain
What are the to ways of preventing osteoporosis
build maxilla peak bone mass
reduce rate of bone mass loss
reduce drug related effects
How do we build maximal peak bone mass
exercise
high dietary calcium intake
How do we reduce rate of bone mass loss
continue exercise and calcium intake
reduce hormone related effects such as estrogen hormone replacement therapy but this is most effective if early menopause
What does estrogen only HRT do
reduces OP risk
increases breast cancer risk
increases endometrial cancer risk for patients who have not had a hysterectomy. can be combined with progestogen to reduce risk
may reduce ovarian cancer risk
increases DVT risk
benefit lost after hRT stops
How do we use drugs to help prevent osteoporosis
consider osteoporosis prevention drugs - biphosphonates
How do bipshonates work
poison osteoclasts and reduce their numbers
What are the two types of biphosphonates
non nitrogenous
nitrogenous
What are the 3 main bisphonates used
alendronate
ibandronate
zolendronate
