metabolic bone disease Flashcards
osteopenia
-Patients are typically asymptomatic.
-Bone density below that for young normal adults but less severe than osteoporosis.
-Diagnosis is by DXA.
-Fracture risk determined with FRAX tool.
-T scores between–1.0 and–2.4
-Asymptomatic; may have back pain
-Vitamin D; lifestyle changes
osteoporosis
-Decreased bone strength
-below -2.5 T score
-Prevalent among postmenopausal women (one in two white and Asian women)
-Also occurs in men and women with underlying conditions or major risk factors associated with bone demineralization
-Chief clinical manifestations:
-Vertebral (commonest) and hip fractures
-kyphosis- wedge fractures
-Only a small proportion are diagnosed and treated
bone mineral density
-A measurement of calcium and other minerals in an area of bone.
-Used to evaluate for osteoporosis, evaluate response to osteoporosis treatment, and assess fracture risk.
-Often obtained using dual-energy x-ray absorptiometry (DXA)
metabolic bone disease
-Defined as a reduction in the strength of bone leading to an increased risk of fractures
-Loss of bone tissue is associated with deterioration in skeletal microarchitecture
-Diagnostic categories for postmenopausal women are based on measurements of BMD (bone mineral density)
-The WHO operationally defines osteoporosis as a bone density that falls 2.5 standard deviations (SD) below the mean for young healthy adults of the same sex—also referred to as aT-scoreof –2.5
-Z-score – age, ethnicity and sex
Z and T score
-Z
-compares bone density to average values for same age and gender
-low Z score (below 2)- less bone mass or losing more rapidly
-T
-help to dx normal bone mass, low bone mass, and osteoporsis
-compares bone density to average bone density of young healthy adults of same gender
-expressed in SD above and below average
-
osteoporosis and hip fracture’s
-Occurs more frequently with increasing age as bone tissue is progressively lost
-In women, the loss of ovarian function at menopause (typically about age 50) precipitates rapid bone loss such that most women meet the diagnostic criterion for osteoporosis by age 70–80
-300,000 hip fractures occur each year
-Most require hospital admission and surgical intervention
-Hip fractures are associated with a high incidence of DVT & PE (20–50%) and a mortality rate between 5 and 20% during the year after surgery
vertebral fractures
-Multiple vertebral fractures lead to:
-Height loss (often of several inches)
-Kyphosis
-Secondary pain and discomfort
-Thoracic fractures: Can be associated with restrictive lung disease
-Lumbar fractures: - abdominal symptoms including distention, early satiety, and constipation
-wedge, biconcave, crush deformity
secondary causes:
-MC: exogenous glucocorticoids
-Hyperparathyroidism
-Cushing’s syndrome
-Hypogonadism
-Hyperthyroidism
-Prolactinoma
-Diabetes mellitus
-Acromegaly
-Pregnancy and lactation
-Immobilization
-Chronic renal failure
-Renal tubular acidosis
screening
-Universal screening of postmenopausal women after age 65 years has been recommended as cost-effective
-USPSTF recommendations for osteoporosis screening
-Fracture Risk Assessment Tool (FRAX)- under 65 high risk score
-women > 65 years - screening for osteoporosis with bone measurement testing to prevent osteoporotic fractures in women 65+
-postmenopausal women younger than 65 at increased risk - screening for osteoporosis with bone measurement testing to prevent osteoporotic fractures in postmenopausal women younger than 65 who are at increased risk for osteoporosis as determined by a FRAX
-men- insufficient evidence to assess balance of benefits and harms of screening for osteoporosis to prevent osteoporotic fractures in men
dx and management of osteoporosis
-based largely on evidence from studies of postmenopausal white women.
-Its application to other populations, including patients with secondary osteoporosis and other methods of assessing BMD, is not established
-antiresorptive - biphosphonates
lab screen
-Measurement of serum calcium (most easily measured as the calcium/creatinine ratio in the second-voided morning specimen)
-Exclude secondary causes of osteoporosis
-Serum phosphorus and alkaline phosphatase [to rule out hyperparathyroidism and osteomalacia]
-25-hydroxyvitamin D
-Serum electrophoresis, blood count, ESR (to rule out myeloma)
-Thyroid function
prevention and tx
-Calcium: Calcium carbonate/citrate; dairy products
-Vitamin D: Slows bone loss and Increases bone mass
-Exercise, Lifestyle, and Prevention of Falls
-½-hour of weight-bearing exercise per day
-Body mechanics and posture
-Smoking cessation and limit alcohol consumption
-Hormone replacement therapy (HRT)
-Lower doses of estrogen (pros and cons)
-Need further study – risk vs. benefit
-Biphosphonates- Allendronate, risedronate -> must take early morning, sit up after, full glass of water
-Denosumab -> inject every 6 months, can decompensate very fast if stopped
-PTH agonists - Teriparatide
rickets and osteomalacia
-Disorders of the mineralization of newly synthesized organic matrix
-In adults, the disorder involves only bone
-In children — abnormalities also occur in the growth plate and in the mineralization of cartilage, leading to characteristic deformities
-Vitamin D deficiency: result of deficient sun exposure and decreased dietary intake or intestinal malabsorption
-Metabolic defects in the vitamin D hormone system, including inadequate activation in the liver and kidney and abnormalities of the vitamin D receptors
osteomalacia
-Asymptomatic - initially
-Bone pain
-Tenderness
-Painful proximal muscle weakness – calcium deficiency
-Decreased bone density
-Pathologic fractures
-Often osteoporosis exist alongside
-softening of bones caused by impaired bone metabolism primarily due to low levels of phosphate, calcium, vit d, or bc resorption of Ca
-impaired of bone metabolism causes inadequate bone mineralization
osteomalacia lab values
-Decreased vitamin D
-Low serum calcium
-Low serum phosphate*
-Increased Alkaline phosphatase
