Metabolic Bone Disease Flashcards
Paget’s disease: what is it
- LOCALISED DISORDER of BONE TURNOVER - LONG BONES + SKULL
- INCREASED BONE RESORPTION - FOLLOWED by INCREASED BONE FORMATION - bone turnover not coupled
- Leads to DISORGANISED BONE = BIGGER, LESS COMPACT, MORE VASCULAR, MORE SUSCEPTIBLE to DEFORMITY + #
Paget’s disease: presentation
• PT. > 40YRS w/ BONE PAIN
* DEEP SEATED BORING PULSATING PAIN * NOTHING RELIEVES IT, EXERCISE HAS NO EFFECT
• Occasionally presents w/ BONE DEFORMITY, EXCESSIVE HEAT OVER PAGETIC BONE, NEUROLOGICAL COMPLICATIONS e.g. nerve deafness
- BONE PAIN + LOCAL HEAT
- BONE DEFORMITY/#
- HEARING LOSS esp. if unilateral, HEADACHE
- PELVIS = HIP PAIN
- SKULL = HEARING LOSS, HEADACHES
- SPINE = COMPRESSION of NN. ROOTS - PAIN, TINGLING, NUMBNESS of LIMB/S
- LEG = WEAKENING BONES cause them to BEND (bowlegged), enlarged/misshapen leg bones put extra stress on nearby joints - OA in KNEE/HIP
COMPLICATIONS:
* # + DEFORMITIES * OA * NEUROLOGIC PROBLEMS - NERVE COMPRESSION * HF * RARE DEVELOPMENT of OSTEOSARCOMA in AFFECTED BONE
Paget’s disease: aetiology
- FHx = STRONG GENETIC COMPONENT: 15 - 30% FAMILIAL (Loci of SQSTMI)
- AGE = > 40YRS
- SEX = M > F
- RESTRICTED GEOGRAPHIC DISTRIBUTION - ANGLO-SAXON ORIGINS
- ENVIRONMENTAL TRIGGER - poss. CHRONIC VIRAL INFECTION w/I OSTEOCLAST (suspect MMR - incidence falling w/ childhood immunisation + less virulent form nowadays)
Paget’s disease: investigations/diagnosis
- ISOLATED ELEVATION of SERUM ALKALINE PHOSPHATASE - commonest presentation nowadays
- X-RAY + ISOTOPE BONE SCAN (triple phase scan)
- Rare to have symmetric Paget’s
Paget’s disease: management
- LIFESTYLE = PREVENT FALLS, ADEQUATE CALCIUM + VITAMIN D in DIET (esp. if taing bisphosphonate), REGULAR EXERCISE
- MEDICAL = IV BISPHOSPHONATE THERAPY - ONE-OFF IV ZOLENDRONIC ACID
- No real side-effects as it’s given once; pt. don’t tend to re-present as it stops Paget’s for years (amount of years is variable, but pt. are elderly so don’t tend to come back)
- ASYMPTOMATIC = NO EVIDENCE TO TREAT asymptomatic Paget’s UNLESS in SKULL/SPINE/AREA REQ. SURGICAL INTERVENTION
- NO Rx = if based SOLELY on ALKALINE PHOSPHATASE
- HEARING TEST
- SURGERY = #, JOINT REPLACEMENT, REALIGN DEFORMED BONES, REDUCE PRESSURE on NN.
Rickets + Osteomalacia: what is it
- RICKETS = GROWING CHILD
* OSTEOMALACIA = ADULT (closed epiphyseal lines)
Rickets + Osteomalacia: presentation
RICKETS CHILD:
* BONE PAIN * SKELETAL DEFORMITIES - SOFT WEAK BONES, BOWING of LEGS, THICKENING of ANKLES, WRISTS, KNEES * DENTAL PROBLEMS - WEAK TOOTH ENAMEL, DELAY in TOOTH ERUPTION, INCREASED CAVITY RISK * FRAGILE BONES - INCREASED # RISK * POOR GROWTH + DEVELOPMENT - HEIGHT RESTRICTION, MUSCLE WEAKNESS (resulting in waddling gait, delay in walking) * SHORT STATURE * HEADS APPEAR LARGE - FONTANELLES DELAY CLOSING * BANDY/BOW LEGS when they START WALKING * EPIPHYSES FLARE - KNOBBLY BITS at ENDS of WRISTS, RIBS, LEGS * FAILURE to THRIVE
OSTEOMALACIA:
* BONE PAIN, MUSCLE WEAKNESS (waddling gait + slower, difficult walking), FRAGILE BONES (more prone to #) * PEOPLE WHO AVOID OUTSIDE e.g. work, fears * NO BONY DEFORMITY - PAIN W/I JOINTS, MUSCLE DYSFUNCTION (cannot get out of chairs as weak muscles) * MICRO # RUNNING THROUGH CORTEX - never become full #, pain localised to micro # (ends of long bones, pepperpot skull - loosened areas of skull)
Rickets + Osteomalacia: aetiology
- SEVERE NUTRITIONAL VITAMIN D/CALCIUM DEFICIENCY causes INSUFFICIENT MINERALISATION causing RICKETS/OSTEOMALACIA
- Vitamin D stimulates absorption of calcium + phosphate from the gut, after which calcium and phosphate become available for bone mineralisation
- SURGERY = GASTRECTOMY, SMALL INTESTINE REMOVAL
- COELIAC DISEASE, MALABSORPTION
- KIDNEY/LIVER DISORDERS
- DRUGS e.g. phenytoin
Rickets + Osteomalacia: investigations/diagnosis
- BLOODS + URINE = CALCIUM, PHOSPHORUS, VITAMIN D LVLS - 25(OH)VIT D (not active form)
- X-RAYS for MICRO #/#
- DEXA SCAN
Rickets + Osteomalacia: management
• BENT LEGS can be TREATED if FOUND EARLY ENOUGH - otherwise SURGEON to STRAIGHTEN LEGS
- SUN EXPOSURE
- DIET = ADEQUATE VITAMIN D + CALCIUM
- VITAMIN D SUPPLEMENTS
Osteogenesis imperfecta: what is it
• GENETIC DISORDER of CONNECTIVE TISSUE - resulting in FRAGILE BONES from MILD TRAUMA (even acts of DAILY LIFE)
Osteogenesis imperfecta: presentation
- Broad clinical range from those who are PRENATALLY FATAL - those only presenting in 40s w/ EARLY ‘OSTEOPOROSIS’
- DISEASE PHENOTYPE VARIES GREATLY - EVEN W/I FAMILY
- LOW ENERGY #; BONES w/ ALTERED SHAPE
- GROWTH DEFICIENCY
- DEFECTIVE TOOTH FORMATION (DENTIGENESIS IMPERFECTA) - DENTINE FEELS PAIN, COLLAGEN UNDERNEATH ENAMEL
- HEARING LOSS - HEARING TEST REGULARLY
- BLUE SCLERA
- SCOLIOSIS
- BARREL CHEST
- LIGAMENTOUS LAXITY - HYPERMOBILE
- EASY BRUISING
- JOINT/BONE PAIN
Osteogenesis imperfecta: aetiology
- GENETIC DISORDER of TYPE 1 COLLAGEN (28 diff. types):
- TYPE 1 = MILDER FORM, when CHILD STARTS WALKING, can PRESENT in ADULTS
- TYPE 2 = LETHAL by AGE 1
- TYPE 3 = PROGRESSIVE DEFORMING w/ SEVERE BONE DYSPLASIA + POOR GROWTH
- TYPE 4 = SIMILAR to TYPE 1, but MORE SEVERE
Osteogenesis imperfecta: investigations/diagnosis
• CLINICAL DIAGNOSIS - FULL MEDICAL Hx + EXAMINATION
- X-RAYS for # + BONE CHANGES
- DEXA
Osteogenesis imperfecta: management
- SURGICAL = TREAT # e.g. long bones have rods implanted to maintain straightness, spine can develop scoliosis
- MEDICAL = PREVENT # (IV BISPHOSPHONATES - can be given to babies, stopped for a while until # start, then re-started + VITAMIN D SUPPLEMENTS)
- PHYSIOTHERAPY
- SOCIAL = EDUCATIONAL + SOCIAL ADAPTATIONS
- HEARING TEST
- ORTHOTICS
Osteoporosis: what is it
- METABOLIC BONE DISEASE - LOW BONE MASS + MICROARCHITECTUAL DETERIORATION of BONE TISSUE
- LEADS to ENHANCED BONE FRAGILITY + consequent INCREASE in # RISK
- DXA BONE SCAN RESULT < -2.5 SDs BELOW YOUNG ADULT MEAN in POST-MENOPAUSAL WOMEN (T-SCORE)
DEFINITION: 1 of below
* MICROARCHITECTURAL DETERIORATION of BONE resulting in INCREASED # RISK * THIN BONES w/ INCREASED RISK of LOW TRAUMA #
Osteoporosis: aetiology
PHYSIOLOGICAL:
* STILL ACCRUING BONE MASS from CHILDHOOD - MID-20s * BONE MASS REMAINS LVL UNTIL MID-40s * STARTS FALLING (1% loss in men; 5% loss after menopause then bone turnover slows to < 1% loss) ○ MEN SHOULDN’T HAVE OSTEOPOROSIS in 40-50s ○ WOMEN LOSE OESTROGEN RECEPTOR in BONE - LOSE PROTECTIVE EFFECTS of OESTROGEN
ENDOCRINE:
* THYROTOXICOSIS * HYPER + HYPOPARATHYROIDISM * CUSHING'S * HYPERPROLACTINAEMIA - also occurs during pregnancy, higher risk of # during pregnancy (osteoporosis of pregnancy) * HYPOPITUITARISM * EARLY MENOPAUSE (anything at all that affects sex hormones)
RHEUMATIC: compounded as they are treated w/ STEROIDS
* RA * ANKYLOSING SPONDYLITIS * POLYMYALGIA RHEUMATICA
GI:
* INFLAMMATORY DISEASE = UC, CROHN'S (STEROIDS) * LIVER DISEASES = PBC, CAH (chronic active hepatitis), ALCOHOLIC CIRRHOSIS, VIRAL CIRRHOSIS (HEP C - can be cured, but # may already be present) * MALABSORPTION = CHRONIC PANCREATITIS, COELIAC DISEASE, WHIPPLES DISEASE, SHORT GUT SYNDROMES, ISCHAEMIC BOWEL - CANNOT JUST PRESCRIBE TABLETS AS THEY WON'T BE ABSORBED
MEDICATIONS:
* STEROIDS * PPI * ENZYME INDUCTING ANTI-EPILEPTICS * AROMATASE INHIBITORS - OESTROGEN INHIBITORS, used in breast cancer, often for prolonged periods of time * GnRH INHIBITORS - PROSTATE CANCER, ENDOMETRIOSIS * WARFARIN
Osteoporosis: investigations/diagnosis
- FRAX (WHO # RISK ASSESSMENT TOOL) - 10YR LIKELIHOOD of BREAKING BONE/BREAKING HIP; NEED to be 40YRS
- > 10% = NEED TO TREAT
- Q FRACTURE (for those 30 - 85YRS, MEN + WOMEN); MULTIPLE VARIABLE incl. CV RISKS, FALLS, TCS - Treacher Collins Syndrome (not bone mineral density, some variables and risks cannot be altered by osteoporotic medications)
- BONE DENSITY SCANNER (DEXA/DXA SCAN) - v. low dose radiation
- DXA SPINE = PELVIS, LUMBAR VERTEBRAE, THORACIC VERTEBRAE
- DXA HIPS
- LATERAL DXA HIPS
- Degenerative changes, calcific aorta can artificially affect results
○ If below = find cause + treat
Osteoporosis: management
PREVENTION:
* MINIMISE RISK FACTORS * ENSURE GOOD CALCIUM + VITAMIN D STATUS - MAY NEED VITAMIN D SUPPLEMENTS * FALL PREVENTION STRATEGIES * MEDICATION • INVESTIGATE WHY PT. OSTEOPOROTIC (don’t need to do if Z score if ok)
TREATMENT: WHEN AT HIGHER RISK of # (normal T-score > -1; osteopenia T-score bwtn -1 and -2.5; osteoporosis T-score < -2.5)
* # RISK ASSESSMENT + # REDUCTION - don't really treat if low risk of #, try to reduce risk of # * REFERRAL for DXA SCANNING BASED on FRAX/Q-FRACTURE SCORE > 10% # RISK at ANY SITE over NEXT 10 YEARS * Rx DECISIONS AFTER DXA SCANNING + INDIVIDUAL REPORT # RISK ~ 20% 10YR RISK = Rx THRESHOLD/PT. HAS # - try to do before
STEROID INDUCED OSTEOPOROSIS = DEPENDS on AGE (< 65YRS - DEXA SCAN + T-SCORE < -1.5 = TREAT; > 65YRS - Rx to PREVENT OSTEOPOROSIS, may also give DXA scan)
Osteoporosis: medications
HRT - oestrogen/testosterone replacing; INCREASED BLOOD COT RISK, BREAST CANCER, HEART DISEASE, STROKE
SERM - diff. agents have diff. oestrogenic/anti-oestrogenic effects at diff. sites; HOT FLUSHES, INCREASED CLOTTING RISK, LACK of HIP PROTECTION
BISPHOSPHONATES - 1st line, poison osteoclasts which spit up contents and drug remains in bone; need adequate renal function + good dental health and hygiene; OESOPHAGITIS, IRITIS/UVEITIS, ONJ, ATYPICAL FEMORAL #
DENOSUMAB - s/c injection every 6 months of monoclonal antibody against RANKL - reduces osteoclastic bone resorption; ALLERG/RASH, SYMPTOMATIC HYPOCALCAEMIA, ONJ, ATYPICAL FEMORAL #
TERIPARATIDE - single daily injection of human PTH (only anabolic rx - builds bone); INJECTION SITE IRRITATION, RARELY HYPERCALCAEMIA, ALLERGY, COST
