ic18 osteoporosis Flashcards
what is “osteoporosis”
a metabolic bone disease characterised by
i) low bone density
ii) microarchitecture disruption (impaired mineralisation)
iii) decr bone strength
iv) incr risk of fractures
what are possible causes of decreased bone mass (which are the most common)
- age *most common
- menopause *most common
- low serum Ca (malnutrition)
- alchol consumption (alcohol leads to incr RANKL which incr bone resorption and (ii) incr oxidative stress which results in osteoblast apoptosis
- smoking
- physical inactivity
- medication use (glucocorticoids, immunosuppressants like cyclosporin, ASM like PB and PHT, GnRH antagonists and agonists, heparin, cancer chemotx, aromatase inhibitors)
- secondary to other diseases (endocrine - hyperPTH, hyperT, DM; GI - celiac, alcohol related liver disease, chronic active hepatitis, IBD, vitD/Ca deficiency)
what are the clinical manifestations of osteoporosis
i) asymptomatic
ii) often undiagnosed until presented with fragility fracture
iii) fractures may then give rise to pain and disability
what are the types of fragility fractures
- spine (vertebral compression)
i) result in height loss and kyphosis (exaggerated forward rounding of the upper back) - hip
i) neck of femur
ii) intertrochenteric - wrist
i) colles - humerus
- pelvis
what are the risk factors of osteoporosis
i) postmenopausal women
ii) men 65yo and above
iii) ageing
iv) family hx of osteoporosis or fragility frac
v) prev fragility frac
vi) hx of falls
vii) low Ca intake (<500mg/d)
viii) excessive alcohol consumption (>2u/d)
ix) low body weight
x) height loss (>2cm within 3yr)
xi) drugs
xii) medical conditions that can decr bone density or incr frac risk
xiii) prolonged immobility
xiv) smoking
xv) early menopause (,45yo)
what tool can be used to screen bone mineral density (elaborate on the scoring and whether any further investigations should be done)
osteoporosis self assessment tool for asians (OSTA) to detect a woman’s osteoporosis risk
high risk if >20 (consider DXA scan bc likelihood of finding osteoporosis is high)
medium risk if 0-20 (consider DXA scan if any other risk factors present)
low risk if <0 (defer DXA)
OSTA score = age in yrs - weight in kg
how is osteoporosis diagnosed
- through hx of fragility fracture
i) at vertebral, hip, wrist, pelvic, humerus, rib
ii) occur spontaneously or from a minor trauma
iii) asymptomatic vertebral fracture can be visually identified as >20% decr in vertebral height - BMD measurement
i) done using dual-energy xray absorptiometry (DXA) of hip and/or spine
ii) T score </= -2.5SD indicates osteoporosis; T score -1 to -2.5SD indicates osteopenia (conduct FRAX); T score >/=-1SD indicates normal bone density - fracture risk assessment tool (FRAX)
i) to be conducted for pts whose T score from BMD measurement reflects osteopenia
ii) consider starting tx if 10yr probability is high for major osteoporotic fracture (>/=20%) or hip fracture (>/=3%)
differentiate between T score and D score (what D score to note of)
T score compares BMD against a young adult ref pop (20yo) while Z score compares BMD against the expected BMD for the pt’s age and sex
Z score of >/= -2SD suggests coexisting problems eg. glucocorticoid tx or alcoholism that can contribute to osteoporosis
differentiate between the two types of DXA
DXA scans generates scores for two locations (hip and spine), typically consider the worse number
hip BMD is q predictive for hip fracture vs spine BMD can be useful in assessing response to tx
how can we identify secondary causes of osteoporosis
look at clinical hx, physical exam and labs
most common labs incl:
i) Cr (determines baseline renal func which can influence agent selected and may also indicate any presence of CKD-MBD)
ii) FBC (show malignancies and malabsorption)
iii) corrected Ca (incr levels of corrected Ca indicate primary hyperPTH or malignancy, decr levels can indicate malabsorption or vitD deficiency)
iv) vitD (determine baseline level, aim for >20mg/mL)
*corrected Ca is an estimate of total Ca conc had albumin func been normal (bc serum albumin level decr w age)
(corrected calcium = serum calcium + 0.8 (4 - serum albumin))
other labs incl:
i) TSH (decr levels of TSH may indicate hyperT or over replacement w thyroxine)
ii) ESR (very high ESR might indicate rheumatological diseases)
iii) alkaline phosphate (incr levels may indicate liver disease, paget’s disease, recent frac or other bone pathology)
iv) serum phosphate (abnormal levels may indicate vitD deficiency or renal phosphate wasting)
v) spot urine Ca/ creatinine ratio (if elevated can indicate idiopathic hyperCa)
vi) serum total testosterone (decr levels can indicate hypogonadism)
what are the clinical risk factors in FRAX
i) age
ii) sex
iii) weight in kg
iv) height in cm
v) prev frac
vi) parent frac
vii) current smoking
viii) glucocorticoids
ix) rheumatoid arthritis
x) secondary osteoporosis (T1DM, osteogenesis imperfecta in adults, long standing untreated hyperT, hypogonadism or premature menopause (<45yo), chronic malnutrition, malabsorption, chronic liver disease)
xi) alcohol >3u/d
xii) BMD
what are the tx for osteoporosis
- lifestyle and diet
i) exercise (weight bearing for 30mins daily, muscle strengthening and balance 2-3x/w eg. walking, elastic band exercises, taichi)
ii) Ca
iii) vitD
iv) smoking cessation and appropriate alcohol intake (<2u/d)
v) educate on fall risk, home safety through fall prevention strategies, types of footwear to reduce risks of falls
(pt specific interventions like for impaired vision/ cataract, footwear, home modifications, medication review) - antiresorptive agents
i) bisphosphonates (alendronate, risedronate, zoledronic acid)
ii) RANKL inhibitors (denosumab)
iii) estrogen (raloxifene)
iv) calcitonin (calcitonin) - anabolic agents
i) PTH analogue (teriparatide)
ii) sclerostin inhibitor (romosozumab)
what is the target of Ca intake and when should supplementation be considered, also consider types of food with high Ca level and ddi of Ca
Ca target: 1000mg/d for healthy adults 51yo and above, 800mg/d for 19-50yo
benefit: slight incr in BMD
ddi:
i) PPI
ii) fiber
iii) bisphosphonates
iv) Fe
v) FQ, tetracyclines
vi) thyroid suppl
(i and ii decr Ca absorption; Ca decr acsorption of iii to vi)
supplementation given: when dietary Ca intake <700mg/d
DIETARY Ca INTAKE
i) milk (diary or non diary) 240mL = 300mg
ii) orange juice 240ml = 300mg
iii) yogurt 138g = 250mg
iv) tofu 0.5cup = 435mg
v) ice cream/ frozen yogurt 0.5cup = 100mg
vi) beans 0.5cup = 60-80mg
vii) green leafy vege cooked 0.5cup = 50-135mg
viii) orange = 60mg
ix) almonds 24pcs = 70mg
x) cottage cheese 0.5cup = 130mg
xi) cheese 28g = 195-335 (hard cheese = higher Ca)
what is the target of vitD intake and when should supplementation be considered, also consider ddi of vitD
target vitD: 600IU/d for 51-70yo, 800IU/d for >70
benefit: reduces falls and confers small reduction in fracture when combined with Ca suppl
ddi: rifampicin, ASM, cholestyramine, orlistat, Al containing product
(orlistat binds to fats and since vitD is fat soluble it will bind to vitD)
fdi: take after or w/o food (bc vitD is fat soluble)
supplementation: 800IU/d cholecalciferol to those at risk or has vitD insufficiency
what are the medications that can incr risk of falls and why
medications below are sedating/ has drowsiness s/e thus can incr risk of falls
i) benzodiazepines
ii) psychotropics
iii) some antidepressants
iv) first gen antihistamine
v) anarex
vi) codeine
