Osteoperosis and Osteomalacia Flashcards
what is osteoporosis?
reduction in density of the bones.
what is osteopenia?
a less severe reduction in bone density than osteoperosis- less strong so more prone to fractures
risk factors for osteopenia
Older age Female Reduced mobility and activity Low BMI (<18.5 kg/m2) Rheumatoid arthritis Alcohol and smoking Long term corticosteroids. NICE suggest the risk increases significantly with the equivalent of more than 7.5mg of prednisolone per day for more than 3 months) Other medications such as SSRIs, PPIs, anti-epileptics and anti-oestrogens
post menopausal women- oestrogen is protective against osteoporosis so unless they are on HRT, they will have less oestrogen
what is the FRAX tool
predicts the risk of a fragility fracture over the next 10 years
age, BMI, co-morbidities, smoking, alcohol, family history, bone mineral density (from DEXA)
gives a % risk of major osteoporotic fracture of hip fracture in next 10 years
bone mineral density
measured using DEXA scan
dual - energy X-ray absorptiometry
measures how much radiation is absorbed in the bones which indicates the density
bone density can be represented as Z score or T score.
cores represent the number of standard deviations the patients bone density falls below the mean for their age. T scores represent the number of standard deviations below the mean for a healthy young adult their bone density is.
T score is most clinically important
WHO classification of T score at the hip and bone mineral density
More than -1
Normal
-1 to -2.5
Osteopenia
Less than -2.5
Osteoporosis
Less than -2.5 plus a fracture
Severe Osteoporosis
how to assess for osteoperosis
- FRAX assessment in women >65, men >75, young patients with risk factors
FRAX outcome without a BMD result will suggest one of three outcomes:
Low risk – reassure
Intermediate risk – offer DEXA scan and recalculate the risk with the results
High risk – offer treatment
FRAX outcome with a BMD result will suggest one of two outcomes:
Treat
Lifestyle advice and reassure
how to manage osteoperosis
conservative: activity + rest maintain healthy weight adequate ca2+ intake adequate vitamin D intake avoid falls stop smoking reduce alcohol
medical:
vitamin D and calcium
calcichew D3 (contains 1000mg of calcium and 800 units of vitamin D cholecalciferol)
bisphosphonate interfere with osteoclast which prevent resorption of bone alendronate 70mg weekly risedronate 35mg weekly zoledronic acid 5mg once yearly IV
what are some side effects of bisphosphonate?
reflux and oesophageal erosions
important to take on empty stomach and sit upright for 30 minutes before moving or eating to prevent reflux
atypical fractures
osteonecrosis of the jaw and external auditory canal
other medical options for osteoporosis (if bisphosphante is contraindicated)
Denosumab is a monoclonal antibody that works by blocking the activity of osteoclasts.
Strontium ranelate is a similar element to calcium that stimulates osteoblasts and blocks osteoclasts but increases the risk of DVT, PE and myocardial infarction.
Raloxifene is used as secondary prevention only. It is a selective oestrogen receptor modulator that stimulates oestrogen receptors on bone but blocks them in the breasts and uterus.
Hormone replacement therapy should be considered in women that go through menopause early.
what is the follow up regime for osteoporosis?
low-risk= do no treat, give lifestyle and follow up in 5 years (repeat assessment)
if on bisphosphonate = repeat FRAX and DEXA after 3-5 years
recommend treatment holiday
break from tx for 18 months - 3 years
what is osteomalacia?
a condition where there is deceptive bone mineralisation which causes soft bones due to insufficient vitamin D
(osteo=bone malacia=soft)
symptoms of osteomalacia
weak bones
bone pain
muscle weakness
fractures
rickets
osteomalacia in children before their growth plates close
what its the pathophysiology of osteomalacia
vitamin D synthesis
vitamin D is a hormone created from cholesterol in the skin in response to UV radiation
standard diet has inadequate levels of vitamin D to compensate for the lack of sun exposure.
deficiency
- reduced skin exposure
- insufficient intake of vitamin D
- malabsorption (IBD)
- CKD (kidneys are essential in metabolising vitamin D into it’s active form)
importance of vitamin D
essential in absorption of ca2+ and phosphate from the kidneys and intestines. vitamin D is also responsible for bone turn over and promoting bone reabsorption to boost serum calcium level
inadequate vit D= inadequate ca2+ and phosphate in the blood = defective bone mineralisation
how does osteomalacia present
Patients with vitamin D deficiency and osteomalacia may not have any symptoms. Potential symptoms are:
Fatigue Bone pain Muscle weakness Muscle aches Pathological or abnormal fractures looser zones (fragility fractures that go partially though the bone)
how do we investigate for osteomalacia / low vitamin D
blood serum 25 hydroxyvitamin D
<25 nmol/L – vitamin D deficiency
25 – 50 nmol/L – vitamin D insufficiency
75 nmol/L or above is optimal
serum ca2+ (low)
serum phosphate (low)
serum ALP (high)
parathyroid (high, 2’)
imaging:
X-ray shows osteopenia (radiolucent bones)
DEXA (low bone mineral density)
how to treat osteomalacia
conservative
medical:
vitamin D supplementation (cholecalciferol)
50,000 IU once weekly for 6 weeks
20,000 IU twice weekly for 7 weeks
4000 IU daily for 10 weeks
A maintenance supplementary dose for of 800 IU or more per day should be continued for life after the initial treatment.
Paget’s disease of the bone
disorder of bone turnover
excessive bone turnover (formation and reabsorption) due to excessive activity of osteoblast and osteoclast
in-cordinated turnover which leads to patchy areas of high density (sclerosis) and low density (lysis)
enlarged + misshapen bones with structural problems which increases the risk of pathological fractures and typically affects the axial skeleton (head and spine)
how does Paget’s present?
Bone pain
Bone deformity
Fractures
Hearing loss can occur if it affects the bones of the ear
*older adults
investigation for Paget’s
bloods: raised ALP LFT normal ca2+ normal PO4- normal
imaging:
xray findings
Bone enlargement and deformity
“Osteoporosis circumscripta” describes well defined osteolytic lesions that appear less dense compared with normal bone
“Cotton wool appearance” of the skull describes poorly defined patchy areas of increased density (sclerosis) and decreased density (lysis)
“V-shaped defects” in the long bones are V shaped osteolytic bone lesions within the healthy bone
how to manage Paget’s?
conservative
medical
- bisphosphonates. interfere with osteoclast activity to restore normal metabolism
- NSAIDs for bone pain
- Ca2+ and vit D
surgery:
for fractures, severe deformity and arthritis
monitor:
check serum ALP and review symptoms
what are some complications of Paget’s?
osteogenic sarcoma (osteosarcoma) bone cancer with poor prognosis. increased focal bone pain, bone swelling, pathological fractures. follow up
spinal stenosis (spinal cord compression). deformity of the spine leads to spinal canal narrowing. can press on spinal nerves- neurological signs and symptoms. MRI and treat with bisphosphonate. consider surgery.
