Osteoporosis Flashcards
Discuss the variation of bone mass throughout an individuals lifetime?
- There is a net gain of bone mass which reaches maturity about 25-30 years of age
- The increase of bone mass, plateaus here for around 10 years
- From 40 years old there will be a net loss in bone mass- this loss is faster in post-menopausal women
What factors impact rate of bone loss?
Genetic factors (75%):
- More likely to develop Osteoporosis if there is a family history of the condition
- Possible involvement of genes- Vitamin D receptor gene, Oestrogen receptor gene, Interleukin-6 gene
Environmental factors:
- Low calcium intake or absorption
- Low vitamin D intake or lack of exposure to sunlight- common in those in residential/nursing homes
- Physical inactivity
- Increased alcohol consumption- the toxicity can decrease bone mineral density- Alcohol can decrease the absorption of calcium via the intestine, or it can have effects on the pancreas and vitamin D metabolism
- Smoking- can cause abnormal metabolism of oestrogen and can decrease the absorption of calcium leading to low bone density
What is osteoporosis?
Osteoporosis is a health condition that weakens bones, making them fragile and more likely to break. It develops slowly over several years and is often only diagnosed when a fall or sudden impact causes a bone to break
- cause by a reduction in bone mass leading to increase bone fragility and susceptibility to fracture
What is the assigning of a T-score in osteoporosis?
Created by WHO that looks at the number of standard deviations by which the individual’s bone mass density (g/cm2) differs from the mean peak bone mass density of younger adults of the same sex.
The fracture risk doubles for every standard deviation below the standard:
Score:
Normal= above -1
Osteopenia= between -1 and -2.5
osteoporosis= -2.5 or less
established osteoporosis= -2.5 or less and presence of a fracture
What are the most commonly bones fractures/broken in osteoporosis?
Hips
Vertebrae
Wrist
pelvis
arm
What is osteopenia?
The stage before osteoporosis where scans show a lower bone mass density than normal, but is not low enough to be diagnosed as Osteoporosis.
What percentage of males and females over the age of 50 have osteoporosis?
Males = 6.7%
Females = 21.9%
This increases further with age to be 50% at 80 years
How is osteoporosis diagnosed?
To diagnose a DEXA scan is used (dual energy x-ray absorptiometry)
This involves laying on your back and a scanning arm is passed over the body
The machine measures the amount of x-rays passed through the body to give a T-score:
Normal= above -1
Osteopenia= between -1 and -2.5
osteoporosis= -2.5 or less
established osteoporosis= -2.5 or less and presence of a fracture
A ‘Z’ score is used instead in those who are children or under 30 but still growing- if score is below -2 it is lower than it should be.
Why can’t traditional X-rays be used to diagnose osteoporosis
- X-rays can’t detect bone loss until 30% of bone mass is lost. By this stage, there is already significant disease
so x-rays cant be used to diagnose osteoporosis or osteopenia
What is primary osteoporosis?
The most common of osteoporosis in which the patient has no other disorders known to cause osteoporosis:
e.g. Post-menopausal osteoporosis
Age or ‘denial’ related osteoporosis
What is secondary osteoporosis?
This is osteoporosis related to a known medical condition e.g:
- Anorexia
- IBD- chrons, collitis
- Endocrine conditions- type 1 DM, Cushing’s syndrome, hyperthyroidism
- Rheumatoid arthirtis
or can be ‘Drug-induced’:
- Most commonly steroid-induced (13% of cases in males and 10% in females) as steroids:
Decrease osteoblast activity- the cells responsible for bone forming
Decrease Ca2+ absorption from the intestine and increase renal Ca2+ renal loss- this causes abnormal parathyroid hormone and vitamin D activity
Suppresses sex hormone production- Oestrogen is important in maintaining bone structure
- also can be impacted by other drugs such as phenytoin, heparin, furosemide, ciclosporin, lansoprazole
What is the fracture threshold?
Is the bone mineral density at which a patient can sustain a fracture with little or no trauma
What is a fragility fracture?
A fracture that occurs as a result of forces that would not ordinary cause a fracture
WHO quantifies this e.g. as a fall from standing height or less- would not usually cause a fracture
What is kyphosis?
A forward curvature of the spine. Can occur as a result of osteoporosis
What is the prognosis of Osteoporosis (mostly after a hip fracture)?
- 50% of patients with a hip fracture, loose ability to live independently
- Excess mortality after hip fracture increases by 20%
- There is an increased risk of further fractures e.g. after an initial vertebral fracture, there is a 7-fold increase in further fracture and a 13% increase in 5 year risk of hip fracture
- Can lead to substantial disability
