Osteoporosis Flashcards
Causes of osteoporosis
- Menopause - lack of estrogen
- Hypogonadism
- Vitamin D deficiency
- Hyperthyroidism
- Coeliac disease
- Primary hyperparathyroidism
- Monoclonal gammopathy of uncertain significance (MGUS)
Diagnostic criteria
- Bone Mineral Density using DEXA scan - T <-2.5
- Fragility fracture after the age of 50
Peak bone mass is achieved at what age
40-50
Options for drugs in Osteoporosis
- Antiresorptive
- Bisphosphantes- Alendronate
- Selective oestrogen receptor modulator - Tamoxifen, Raloxifen
- Oestrogen
- Calcitonin
- RANKL inhibitor - Donesumab
- Anabolic
- PTH
Examples of anti resorptive drugs used in osteoporosis
- Bisphosphonates : inhibits osteoclast - apoptosis . Alendronate, rerisdronate, etidronate, pamidronate, zolendronate
- Raloxifene - estrogen receptor modulator (also called SERMS, selective estrogen)
- Denosumab - binds to RANKL
Anabolic agent used in osteoporosis
Teriparatide - synthetic parathyroid hormone increases osteoblastic activity
DDx for osteoporosis
- Osteopenia
- Multiple myeloma
- Osteomalacia
- Chronic kidney disease
- Primary hyperparathyroidism
- Metastatic bone malignancy
- Vertebral deformities
- Osteogenesis imperfecta
- Hypogonadism
- Cushing’s syndrome
- Rhematoid arthritis
- Mastocytosis
Two main factors that determine risk of osteoporosis
- Peak bone mass
- genetics
- ca, diet, exercise
- Rate of bone loss
Risk factors for low bone mass
Non-modifiable
- Age
- Race
- Female
- Early menopause
- Slender build
- Family history
Modifiable
- Low Ca intake
- Low vit D intake
- Oestrogen deficiencyy
- Sedentry lifestyle
- Smoking
- Alcohol
- Caffeine
- Medication
Bone mass and quality in Osteoporosis
- Loss of bone mass
- Reduction in bone quality
- loss of horizontal struts
- loss of connectivity
- conversion of trabecular plates to rods
- Resorption pits are “stress concentrators”
- Unfavorable geometry
Definition of osteoporosis
systemic skeletal disease chracterised by low bone mass and micro-architectural deterioriation of bone tissue resulting in increase fragility and risk of fracture
Risk factors for Osteoporotic fracture
Major
- Personal history of fracture as an adult
- history of fragility fracture in 1st degree relative
- low body weight
- current cigarette smoking
- >3 months of oral corticosteriod use
Additional
- Estrogen deficiency at an early age
- dementia
- excessive alcohol use
- recent falls
- inadequate physical activity
- poor health/fragility
- impaired vision
- lifelong low Ca intake
Investigations for suspected osteoporosis
- X-ray - fracture
- Bloods
- Bone turnover markers : Ca, PO4, ALP, Osteocalcin (urine = increased turnover), urine hydroxyproline
- Bone pathogenic marker : TSH, PTH, Ca, PO4, EUC, Cr, Testosterone, Vitamin D, Serum and urine electrophoresis
- Bone scan - detects osteoblastic activity + new fracture, pagets and metastatic lesions
- MRI - new fracture
- BMD diagnosis
- Bone Biopsy
- Bone u/s - not standardised
What is the difference between T-score and Z-score in DXA scan
T score = compared to mean peak bone mass, what is desirable
Z score = compared to age and gender matched controls, what is expected, if bone mass is unusually low
Important risk factors in Fracture risk calculations
Age
BMD
Hx of prior fractures