osteoporosis Flashcards
Define osteoporosis
disease characterised by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility in fracture risk’
Bone mineral density T score
List risk factors for developing osteoporosis
postmenopausal women caucasian/asian hx of maternal hip fracture sex hormone deficiency low body mass lifelong low Ca intake sedentary lifestyle, immobility excessive alcohol use & cigarette smoking prior low trauma fracture
List the secondary causes of diminished bone density?
these sec causes of bone loss should be excluded w a complete hx, physical exam and lab tests
Endocrine disorders
Cushing’s disease, hyperparathyroidism, hyperthyroidism, prolactinoma, hypogonadism
Celiac disease and other causes of malabsorption
Vitamin D deficiency
Hepatic or renal dysfunction
Genetic disorders, e.g., osteogenesis imperfecta
Systemic inflammatory disease, e.g., RA, IBD
Anorexia nervosa
Malignancies, e.g., multiple myeloma
Corticosteroids
What factor plays a key role in bone loss?
age related bone loss in women and men begins around the age of 40. In women over this age, about 35% of compact bone and 50% of spongy bone in the skeleton is lost during their remaining lifetime. In contrast, men lose about two-thirds of this amount.
Women lose more bone because of menopause which is a/w decreased oestrogen levels. Additionally women have less bone to begin w so are generally at a greater risk for osteoporosis
What factor plays a key role in fractures ?
AGE
incidence increases w age
2/3 women >80= osteoporotic fractures
1/3 60-70 = fractures
What are the pathologic findings w osteopenia and osteoporosis
osteopenia - mineral density lower than normal- precursor to osteoporosis
The effects of postmenopausal bone loss are most apparent in trabecular/spongy/cancellous bone where the rate of bone loss increases 3 fold immediately following menopause
Gross features: Loss of cancellous bone, accentuation of vertical trabeculae in spine
microscopic
Thin trabeculae disconnected from each other
Increase in osteoclastic activity- bone resorption (may be uneven) or increased percentage of surface with resorptive pitting
vertebrae rich in trabecular bone- thus more prone to fractures
Diagnosis of osteoporosis
BMD T score
radiographic measurement of bone density
What is BMD T score
T score compare Bone mineral density to ideal peak mineral density and are measured in standard deviations above and below peak BMD.
BMD- measures degree of bone loss (g/cm2) . provides an estimate of a person’s fracture risk
What is the normal,osteopenia,osteoporosis a/ T score
Normal: more than or equal to -1.0
Osteopenia : -1.0 to -2.5
Osteoporosis: less than or equal to -2.5
Severe osteoporosis: less than or equal to -2.5 w/ fragility fractures
What are the factors that increase absolute fracture risk?
older age
prior fracture
lower T scores
multiple risk factor
Pharm Treatment of osteoporosis
Calcium (1000mg/day) and vit D(800iu) supplement
bisphosphonates (apoptosis of osteoclasts) eg alendronate,residronate
hormone replacement
selective oestrogen receptor modulators
PTH
rank ligand inhibitor
Other non pharm tx of osteoporosis
smoking,excess alcohol prevention
weight bearing exercises
good diet
correct sec causes where possible
Describe examples of bisphosphonates
Alendronate Primary nitrogen terminal bisphosphonate 70mg once weekly dose 5-7% gains in BMD & 40% reduction in fracture rate Long t ½ of elimination ? years
Residronate bisphosphonate w heterocyclic ring 35 mg po once weekly 5% gain in BMD & 40% reduction in fracture risk T ½ of excretion about 20 days
Ibandronate- 150mg orally once monthly
zoledronic acid iv 5mg once yearly
Complications of BP
osteonecrosis of jaw
oesphagitis from oral bisphosphonates
Example of anabolic agents
teriperatide (PTH) - 20mcg s/c daily
most potent anabolic agent
increases BMD seen often used for severe osteoporosis
strontium ranelate- anti resorbitive and anabolic ;; cardiac risk
Example of hormones
HRT – consider for early post menopausal patients when indicated for symptom management – is effective note increased risk breast cancer after 5 yrs
Raloxifene – a SERM – 60 mg/d (HRT for bones not uterus or breast) - proven for vertebral fractures
Testosterone for deficient men
How does oestrogen deficiency cause osteoporosis?
Pathophysiology in post menopausal woman?
accelerates bone resorption by
-increasing the activity of bone remodelling units and the number of osteoclasts recruited to resorption sites
-increasing osteoclast lifespan, as well as the formation of new osteoclasts. Thus, more bone is resorbed during resorption phase
-reducing osteoblast lifespan. Therefore, less bone is formed during the formation phase
-altering synthesis of both growth factors and degradative factors that act on bone
Together, these changes prolong the resorption phase of the remodelling cycle and shorten the formation phase
Outline glucocorticoid induced osteoporosis
long term use of oral glucocorticoids in chronic disease (correlates to fracture risk)
-asthma,COPD, RA,IBD,lupus
regardless of age/gender
alot of bone loss in as little as 3 months
eg prednisone
spine fracture incidence higher–trabecular bone loss effect
Pathophysiology of glucocorticoid induced osteoporosis
corticosteroids ultimately cause rapid bone loss
- decreased bone formation, inhibits osteoblasts and testoterone which leads to remodelling imbalance– rapid bone loss
- increased osteoclasts, inhibits oestrogen-> increased bone resorption–rapid bone loss
- increased Ca excretion -> sec hyperparathyroidism- >increased bone resorption – rapid bone loss
- reduced absorption of dietary calcium -> sec hyperparathyroidism->increased bone resorption–rapid bone loss
