Osteoporosis PDF

Osteoporosis Definition  WHO Definition 1994: A skeletal disease characterised by low bone mass and deterioration of the microarchitecture of bone tissue é a consequent increase in bone fragility and susceptibility to low trauma fractures.  Bone density measured relative to the population me...

Osteoporosis Definition  WHO Definition 1994: A skeletal disease characterised by low bone mass and deterioration of the microarchitecture of bone tissue é a consequent increase in bone fragility and susceptibility to low trauma fractures.  Bone density measured relative to the population mean in young adults  Normal- bone mineral density above 1 standard deviation below the mean  Osteopenia- 1- 2.5 standard deviations below the mean for a young adult  Osteoporosis- > 2.5 standard deviations below the mean for a young adult 108  Osteoporosis Incidence Incidence is difficult to measure, as most cases are not recorded until a fracture has occurred. The National Osteoporosis Society: state that at least 1:3 ♀ & 1:12 ♂ will develop osteoporosis. 109  Osteoporosis Etiologic Classification I.. Primary: (i.e. no cause; but occurs as an exaggeration of physiological bone depletion that accompany aging and decrease gonadal activity). More in: 1. Caucasian or Asian, Females é Low body mass index. 2. Blond hair, red hair, hypermobility & adolescent scoliosis have genetic predisposition. 3. Family history of fracture 110  Osteoporosis Etiologic Classification II.. Secondary:: 1. Lifestyle and nutritional: Smoking, alcohol, Sedentary 2.Medical Condition: a) Anorexia nervosa b) RA c) Multiple Myeloma d) Chronic RT or GI disease e) Transplantation f) Early menopause 30% of bone mass 118 119 120 121 122 123  Osteoporosis INVESTIGATIONS  Routine diagnostic procedures 1. History for risk factors 2. Physical examination, including ruling out causes of falling, etc 3. PXR spine. Although >30% bone loss required to be visible, there may be silent wedges 4. Bone mineral Density measurement 5. Blood tests, CBC, ESR, serum biochemistry, TFT to rule out causes of bone weakness 6. Testosterone and Gonadotrophin levels in men 124  Osteoporosis INVESTIGATIONS  Optional 1.Serum CA, PHOSPHATE (fasting)/also urinary excretion is measured 2. Serum PTH (assay of the COOH terminal; not in CRF) 3. Serum 25--OH D (plasma electrophoresis) 4. Markers for bone formation- Bone specific ALKPH & OSTEOCALCIIN 5. Markers for resorption: increase urine PYRIDINIUM & TELOPEPTIDES (Collagen cross-link breakdown) 6. Less accurate is the urinary HYDROXYL--PROLINE e.g. in Paget‟s 7. BM BIOPSY after tetracyline labelling, can rule out osteomalacia (decrease bone turn over) 125  Osteoporosis N.B The GOLD STANDARD TEST is measurement of BMD (g/cm3) of the spine and hip Only vertebral measurements can be used to assess effectiveness of treatment at present. 126  Osteoporosis Bone measurement techniques: 1. DEXA SCANS (Dual Energy Xray Absorptiometry)  Simultaneous measurement of the passage of Xrays through the body é 2 diff.energies.  Low Radiation, accurate, Can be performed on hip, spine, whole body, or any where  If T score is > -1....................................... reassure patient  If Tscore between (-1)&(-2)................. request DEXA of hip/spine  If Tscore < -2 (more -ve)....................... treat, If monitoring required, refer for DEXA 127  Osteoporosis Bone measurement techniques: 2.. RADIOGRAPHIC ABSORPTIOMETRY 3.. SINGLE PHOTON XRAY ABSORPTIOMETRY (SPA) 4.. QUANTITATIVE COMPUTER TOMOGRAPHY  An external bone mineral reference phantom is scanned é patient to calibrate the CT values  More sensitive in vertebra than DEXA (measure BMD/cm3)  However, increase radiation, cost, decrease precision  Used for assessment of vertebral # risk, and follow up. 5.. QUANTITATIVE ULTRASOUND  Inexpensive, small, portable, does not involve radiation  Different instruments ---- different readings, ð different calibration, analysis software used  Can be used for screening. 128  Osteoporosis Differential diagnosis: 129  Osteoporosis Prevention 1.Increase load bearing exercise in young women 2. Increase intake of calcium & vit D 3. Decrease smoking & alcohol intake 4. Decrease drug abuse 5. Decrease house held falls. 6. Evaluate post menopausal women for HRT 7. Evaluate high risk group e.g. those on steroid, considering DEXA and treatment 130 131  Osteoporosis Treatment 1] Calcium + Vit. D supplements  Minimum daily intake of ca should be met.  People > 65yrs  Adding 500mg calcium & 700IU Vit. D---- decrease # by 50% over 3yrs of taking supplements 2] Calcitriol (1,25 dihydroxycholecalciferol)  The active metabolite of vit D. 0.25 μg/d  Decrease risk of VERTEBRAL #.  Need monitoring of plasma calcium 132  Osteoporosis Treatment 3] HRT (OESTROGEN)  Increase bone density by 2% /y  Advantages:  Prevent osteoporosis and decrease osteoporosis progression in PMW  Also has a role in steroid induced osteoporosis  Increase bone density by 2% /y  If given for 5-10 y from the menopause---- decrease risk of # 50%  Other benefits: loss of menopausal symptoms, cardiovascular protection  Disadvantage:  Bone loss may happen again if HRT discontinued (2% /y)  Contraindications:  Risk of endometrial carcinoma, Br.cancer, vaginal bleeding 133  Osteoporosis 4] Bisphosphonates  Synthetic analogues of inorganic pyrophosphate. Inhibit bone resorption by osteoclasts 5] Strontium Ranelate (Protelos®)  New class of drugs that act by ⊕ osteoblasts & ⊖ osteoclasts 6] Teriparatide (Forteo®) is a recombinant parathyroid hormone,  used in the treatment of advanced cases, very effective, expensive.  ⊕ osteoblasts --- NBF right away 134  Osteoporosis 7] Selective Oestrogen Receptor Modulators Raloxifene (Evista®)  Advantage o Work like oestrogen at bone without other harmful effects  Disadvantage: o Increase PMW symptoms --- not to be given within 5 y of menopause 8] Calcitonin (Miaclacic®)  Dose: Nasal form at dosages of 200 IU/d  Advantages: o Non sex, non steroid hormone o ⊖ of osteoclasts & increase bone mass o Can be used for analgesia in osteoporotic #s without inhibiting healing 135  Osteoporosis 9].Nafl (sodium fluoride) Given in low dose (slow release) é Ca supplements ⊕ osteoblasts Increase bone density (but bone quality would be affected in high doses) 136