Bone disease Flashcards
features of bone
- load bearing
- dynamic
- self repairing
what is bone?
mineralised connective tissue
Components of bone
- calcium
- phosphate
- vitamin D
parathyroid hormone actions
- maintains serum calcium level
- increases calcium release from bone
- reduces renal calcium excretion
What is hypoparathyroidism?
low serum calcium
primary hyperparathyroidism causes
- gland dysfunction e.g. tumour
- high serum calcium results
What do both hyper- and hypoparathyroidism lead to?
increased bone resorption
Vitamin D problems are usually caused by…
Low sunlight exposure
- housebound
- dark skinned in northern country
Poor GI absorption
-poor nutrition
- small intestinal disease leading to malabsorption
drug interactions
- some anti epileptic drugs such as carbamazepine and phenytoin
often combination of factors
Osteromalacia - features
- poorly mineralised osteoid matrix
- poorly mineralised cartilage growth plate
osteoporosis features
- loss of mineral and matrix
- leads to reduced bone mass
Osteomalacia during bone formation is known as…
Rickets
What is osteolomalacia related to?
- calcium deficiency
- serum calcium preserved at expense of bone
osteomalacia bone effects
Bones bend under pressure
- ‘bow legs’
- vertebral compression in adults
bones ache to touch
osteomalacia hypocalcaemia effects
- muscle weakness
- facial twitching from CNVII tapping
- carpal muscle spasm
Osteomalacia management
correct cause
- malnutrition
- control GI disease
sunlight exposure
- 30 mins x 5 weekly
dietary vitamin D
Osteoporosis is…
- a reduced quantity of normally mineralised bone
- an age-related change
- inevitable
Osteoporosis risk factors
Age
sex - more likely in females
endocrine
- oestrogen and testosterone deficiency
- cushings syndrome
genetic
- family history
- race - Caucasian and asian women
- early menopause
patient factors
- inactivity
- smoking
- excess alcohol use
- poor dietary calcium
medicinal drugs use
- steroids
- anti-epileptics
peak bone mass is at age…
24-35 years
osteoporosis incidence in women aged 50, 70 and 80
50 = 15%
70 = 30%
80 = 40%
Possible reasons why osteoporosis is more common in females
- males have higher peak bone mass
- oestrogeen withdrawal increases bone mass loss rate in women
- less exercise in women?
osteoporosis effects
increased bone fraction risk
- particularly lone bones e.g. femur
effects on vertebrae
- height loss
- kyphosis and scoliosis
- nerve root compression = back pain
osteoporosis lifetime risk of hip fracture >50 years of age
17.5% - women
6% - men
effects following osteoporosis related hip fracture
20% increase in 5yr mortality
- maximal in initial 5 months
40% unable to walk unaided
60% unable to live independently
Osteoporosis prevention
build maximal peak bone mass
- exercise
- high dietary calcium intake
reduce rate of bone mass loss
- continue exercise and calcium intake
- reduce hormone related effects: oestrogen hormone replacement therapy = most effective if early menopause
reduce drug related effects
- consider osteoporosis prevention drugs (bisphosphonates)
Hormone replacement therapy - summarise
oestrogen only
- reduces osteoporosis risk
- increases breast cancer risk
- increases endometrial cancer risk in patients who have not had a hysterectomy
- may reduce risk of ovarian cancer
- increases DVT risk
benefit lost after HRT stops - returns to normal 5 years post treatment
How to reduce risk of endometrial cancer risk in oestrogen therapy
combine with progestogen
bisphosphonates - effectiveness
50% reduced risk of vertebral fracture
other risk of fracture reduced by 30-50%
benefit lost if drug discontinued
can be combines with HRT
