metabolic bone disease Flashcards

1
Q

osteopenia

A

-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

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2
Q

osteoporosis

A

-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

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3
Q

bone mineral density

A

-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)

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4
Q

metabolic bone disease

A

-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

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5
Q

Z and T score

A

-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
-

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6
Q

osteoporosis and hip fracture’s

A

-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

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7
Q

vertebral fractures

A

-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

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8
Q

secondary causes:

A

-MC: exogenous glucocorticoids
-Hyperparathyroidism
-Cushing’s syndrome
-Hypogonadism
-Hyperthyroidism
-Prolactinoma
-Diabetes mellitus
-Acromegaly
-Pregnancy and lactation
-Immobilization
-Chronic renal failure
-Renal tubular acidosis

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9
Q

screening

A

-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

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10
Q

dx and management of osteoporosis

A

-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

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11
Q

lab screen

A

-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

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12
Q

prevention and tx

A

-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

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13
Q

rickets and osteomalacia

A

-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

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14
Q

osteomalacia

A

-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

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15
Q

osteomalacia lab values

A

-Decreased vitamin D
-Low serum calcium
-Low serum phosphate*
-Increased Alkaline phosphatase

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16
Q

prevention and treatment

A

-Adequate sunshine daily
-Dietary intake
-Vitamin supplements
-Vitamin D 50,000 IU
-Phosphate supplements prn

17
Q

rickets

A

-Rickets occurs before closure of the epiphyses
-Enlargement of cartilage at the growth plate:
-Rachitic rosary at the costochondral junctions
-Widening of the cartilaginous ends of the long bones

-Impaired mineralization results in bowing of long bones.
-Nutritional rickets, Congenital, Rickets of prematurity, Vitamin D resistance (type I and type II), Neoplastic rickets, Hypophosphatemic rickets, Drug-induced rickets
-Radiologically, widening, cupping, and fraying of the metaphyses are seen

18
Q

rickets: fray, splay, cup

A

-widening and irregularity of the growth plate (fraying)
-widening of metaphyseal end of the bone (splaying)
-concavity of the metaphysis (cupping)

19
Q

rickets

A

-Severe vitamin D deficiency causes:
-Muscle weakness combined with the deformity of the chest wall, causes an increased incidence of pneumonia
-Most common deformity - bowing of the legs
-In severe cases bone pain and weakness may cause the patient to be bedridden

-Management
-Sunshine
-Vitamin D3
-Other