Osteoporosis and bone health Flashcards
Describe bone remodelling?
Osteoclasts resorb bone whilst osteoblasts make new bone
What is osteoporosis? what is the pathophysiology?
low bone mass, large spaces and breaks in microscopic architecture
-increase in bone resorption and decrease in bone formation
describe the age-related changes to bone mass
-bone mass increases until 30yo, slow rate bone loss starts 40yrs, rapid bone loss during the menopause due to estrogen deficiency
What factors influence peak bone mass?
¥ Genetics (70-80 %) ¥ Body Weight ¥ Sex hormones ¥ Diet ¥ Exercise
What factors influence bone loss?
¥ Sex hormone deficiency ¥ Body weight ¥ Genetics ¥ Diet ¥ Immobility ¥ Diseases ¥ Drugs eg glucocorticoids, aromatase inhibitors
What are secondary causes of osteoporosis?
Endocrine:
eg hyperthyroidism, hyperparathyroidism,
Cushing’s disease, type 1 diabetes
Gastrointestinal:
eg coeliac disease, IBD, chronic liver disease, chronic pancreatitis
Respiratory:
eg CF, COPD
Chronic kidney disease
How is osteoporosis diagnosed?
¥ Bone mineral density predicts # risk independently of other risk factors
¥ DEXA scans are the most widely used method of measuring BMD
¥ Osteopenia (low bone mass) :BMD >1 SD below the young adult mean but <2.5 SD below this value
¥ Osteoporosis : BMD ≥ 2.5 SD below the young adult mean
¥ Severe osteoporosis : BMD ≥2.5 SD below the young adult mean with fragility fracture
¥ If younger than 20 y, only Z score reported
what do the DEXA scan scores mean?
¥ DEXA scans reported with reference to the number of standard deviations from the mean
¥ T score relates to young adult female population mean
¥ Z score relates to age-matched female population mean
¥ Normal : BMD within 1 SD of the young adult reference mean
Therapeutic intervention for osteoporosis should be targetted to those at high risk of low impact fracture:
-what are the risk factors for fracture?
¥ Previous fragility fractures ¥ Current use or frequent past use of oral glucocorticoids ¥ History of falls ¥ Family history of hip fracture ¥ Other secondary causes of osteoporosis ¥ Low BM (<18.5) ¥ Smoker (>10 cigarettes per day) ¥ Alcohol intake >4 units per day
- Colles fracture = doubles hip fracture risk
- one hip fracture = increased risk to opposite hip
- spine fracture increased by any previous fracture independantly of bone density
WHO fracture risk calculator:
¥ Allows calculation of absolute risk by incorporating additional risk factors rather than just BMD.
¥ Prediction of 10 year fracture risk of major osteoporotic fracture or hip fracture
¥ Some limitations
What is included in the assessment of bone health?
History and examination U+E’s LFT’s Bone biochemistry FBC PV TSH
Consider : Protein electrophoresis/Bence Jones proteins Coeliac antibodies Testosterone 25OH Vitamin D PTH
When is osteoporosis treated?
• majority of patients, consider treatment with antiresorptive therapy when T score = - 2.5
• if ongoing steroid requirement >/=7.5mg prednisolone for 3 months or more or if there is a prevalent vertebral fracture, consider treatment with T score < -1.5
-if osteopenic with a vertebral fracture
What is included in lifestyle advice for the management of osteoporosis?
¥ High intensity strength training ¥ Low impact weight bearing exercise (standing, one foot always on the floor) ¥ Avoidance of excess alcohol ¥ Avoidance of smoking ¥ Fall prevention
Describe the dietary recommendations in the management of osteoporosis?
¥ RNI 700mg calcium (2-3 portions from milk and dairy foods group)
¥ Postmenopausal women aim dietary intake 1,000mg calcium per day to reduce fracture risk (3-4 portion calcium rich foods)
¥ Non-dairy sources include bread and cereals (fortified), fish with bones, nuts, green vegetables, beans
When should patients be given calcium and vit D treatment?
¥ Postmenopausal women unable to achieve 1000 mg calcium from diet should take in tablet form
¥ Vitamin D supplementation not required for people < 65 years who have adequate sun exposure
¥ 10 µg Vitamin D supplement for > 65 years
¥ 20 µg Vitamin D supplement for frail, elderly housebound women
What is the first line treatment for osteoporosis?
Oral bisphosphonates
- alendronate and risedronate
- cause osteoclast apoptosis
