Osteoporosis Flashcards
Defintion
Reduced bone density (defined as > 2.5 standard deviations below peak bone mass achieved by healthy adults (i.e. T-score > 2.5)) resulting bone fragility and increased fracture risk
Aetiology (primary)
o Idiopathic (if < 50 yrs)
o Post-menopausal
Aetiology (secondary)
o Malignancy - myeloma, metastatic carcinoma
o Endocrine: · Cushing's disease · Thyrotoxicosis · Primary hyperparathyroidism · Hypogonadism
o Drugs - corticosteroids, heparin
o Rheumatological - rheumatoid arthritis, ankylosing spondylitis
o Gastrointestinal:
· Malabsorption (e.g. coeliac disease, partial gastrectomy)
· Liver disease (e.g. primary biliary cirrhosis)
· Anorexia
Risk factors
o Age o Family history o Low BMI o Low calcium intake o Smoking o Lack of physical exercise o Low exposure to sunlight o Alcohol abuse o Late menarche o Early menopause o Hypogonadism
Epidemiology
· COMMON
· In > 50 yrs
o Females: 1/3
o Males: 1/12
· More common in CAUCASIANS than Afro-Caribbeans
Presenting symptoms
· Often ASYMPTOMATIC until fractures occur
· Characteristic fractures:
o Neck of femur (after minimal trauma)
o Vertebral fractures (leading to loss of height, stooped posture and acute back pain on lifting)
o Colles’ fracture (of the distal radius after falling on an outstretched hand)
Signs on physical examination
· Often NO SIGNS until complications develop:
o Tenderness on percussion (over vertebral fractures)
o Thoracic kyphosis (due to multiple vertebral fractures)
o Severe pain when hip flexed and externally rotated (suggests NOF fracture)
Investigations (DEXA)
· DEXA (Dual-Energy X-Ray Absorptiometry) Scan
o T-score: the number of standards deviations the bone mineral density measurement is above or below the young normal mean bone mineral density
o Z-score: the number of standard deviations the measurement is above or below the age-matched mean bone mineral density. Z-score may be helpful in identifying patients who may need a work-up for secondary causes of osteoporosis
Investigations (other scans)
· X-Ray
o Used to diagnose fractures
o Often normal because it takes > 30% loss of bone density before showing any changes in radiolucency or cortical thinning
o May show biconcave vertebrae and crush fractures
· Isotope Bone Scans
o Highlights areas of stress and microfractures
Investigations (bloods)
o Calcium
o Phosphate
o ALP
o IMPORTANT: these are NORMAL in PRIMARY osteoporosis