Metabolic Bone Diseases

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Metabolic Bone Diseases

• Osteoporosis
• Osteomalacia
• Pagets Disease

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Osteomalacia

• Overview
• A disease in which the bone becomes abnormally
  soft resulting in marked deformities of weight
  bearing bones and pathologic fractures.
  Demineralized bone.

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• Pathphysiology
• Vitamin D deficiency that results in failure of
  normal bone calcification
• Incidence
• Adults, mainly women
• Endemic in the Orient and in individuals with no
  exposure to sun
• Occasionally in strict vegetarians
• Occasionally in post gastrectomy patients
• Women, who have multiple frequent pregnancies and
  who breast feed
• Patients on long-term anti-convulsants,
  phosphate-binding antacids, tranquilizers,
  sedatives, muscle relaxants, diuretics
• Small intestine disease
• Celiac
• Crohns
• Small bowel resections

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• Complications
• Fractures
• Bone deformities

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Assessment

• History
• Vague, generalized skeletal pain and tenderness,
  especially lower back and lower extremities
• Waddling or limping gait
• Decreased intake or absorption of Vit. D
• Physical deformities
• Deformities, particularly weight bearing
  structures
• Kyphosis
• Muscle weakness
• General malaise

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• Radiographic findings
• Generalized demineralization of bone
• Pseudofractures --- Loosers zones
• Compression fractures of the vertebrae
• Bowing deformities of the long bones
• Laboratory findings
• Serum calcium low
• Serum phosphorus low
• Alkaline phosphatase moderately elevated
• Treatment
• Falls prevention
• Calcium supplement
• Vitamin D and exposure to sunlight
• High protein diet
• Weight bearing exercises
• Behavior modification (? alcohol, tobacco,
  caffeine)

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Osteoporosis

• Metabolic bone disease characterized by low bone
  mass with consequent increase in bone fragility
  and susceptibility to fracture
• Inconspicuous onset and progression and often
  undetected until a fracture occurs
• SILENT DISEASE

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Magnitude of Osteoporosis

• 28 million in US
• 80 are women
• 1.5 million fxs/yr
• Hip fxs
• 10-20 die within 1 year (? with age)
• 15-25 will require long term institutional care
• Cost of acute and long term care associated with
  osteoporosis 14 billion annually (38
  million/day) by 2015

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Osteoporosis

• Pathophysiology
• Bone remodeling
• Osteoblast build new bone tissue
• Osteoclast resorb old bone tissue
• Bone building activity peaks at 30 35 years of
  age
• Osteoporosis
• Bone resorption (osteoclastic activity) exceeds
  bone building (osteoblastic activity) and bone
  density decreases

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• Bone Mineral Density (BMD)
• Bone strength
• Peaks between 30/35 years
• After age 35 bone resorption exceeds bone
  building activity
• 1 / yr until sex hormones ?
• 1st 5 yrs. after menopause loss is 3-5/year
• Trabecular (spongey) bone is lost 1st followed by
  cortical bone
• BMD (bone strength) ?
• ? Fractures (vertebra, wrist, hip)
• Measuring BMD
• T-scores
• of standard deviations above or below the
  average BMD
• -1 to 2.5 osteopenia (low bone mass)
• below -2.5 osteoporosis

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Clinical Manifestations

• Areas most frequently involved
• Vertebral column
• Kyphosis (Dowagers hump)
• Compression fxs (T8 L3)
• ? height (2-3 inches)
• Painful
• Distal Radius
• Hip

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Laboratory Assessment

• None for osteoporosis
• Rule out other diseases
• Serum calcium
• Vitamin D
• Phosphorus
• Alkaline phosphatase

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Radiographic Assessment

• Xray
• Osteoporosis evident only after 25 40 bone
  loss
• Quantative CT (QCT)
• Measures done density of vertebral bone
• Dual energy x-ray absorptiometry (DEXA)
• Best available tool to measure BMD
• Full body measures (wrist, vertebrae, hip)
• Ultrasound
• Best used for screening

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Ultrasonic Bone Densitometer
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Measuring BMD

• T- scores
• of standard deviations below normal 30-35 year
  old bone tissue
• -1 to 2.5 osteopenia
• -2.5 osteoporosis

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Interventions

• Drugs
• Diet
• Exercise
• Education

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Drug Therapy

• Estrogen
• Calcium supplements
• Vitamin D
• Biphosphonates
• Selective estrogen receptor modulators (SERMs)
• Calcitonin

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Estrogen

• Initiated with menopause at the lowest dose
  possible --- 0.625 mg.
• Side effects
• Endometrial cancer
• Breast cancer
• DVT
• Progesterone
• May be added to estrogen to prevent endometrial
  Ca for clients with an intact uterus
• Birth control pills
• Low dose estrogen

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Calcium

• Calcium carbonate
• Cheapest, most available
• Take with meals

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Vitamin D

• 400 IU/ day
• Contained in multi vitamin

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Biphosphonates

• Inhibit bone resorption
• alendronate (Fosamax)
• 5 mg/ day for prevention
• 10 mg/day Rx for osteoporosis
• 75 mg/ week (1 x/wk dosing)
• Side effects
• Esophagitis
• Take on empty stomach
• Remain upright 30 minutes
• Contraindicated
• GERD, poor renal function, hypocalcemia
• etidronate (Didronel)
• Similar to Fosamax

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Selective Estrogen Receptor Modulators

• raloxifene (Evista) --- 60 mg/day
• Very similar to estrogen but does not stimulate
  breast or endometrial tissue
• Increases BMD
• Reduces bone resorption
• Decreases cholesterol
• Side effects
• DVT

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Calcitonin

• Thyroid hormone that inhibits osteoclastic
  activity plus an analgesic effect
• RX
• Osteoporosis
• Pagets disease
• Hypercalcemia associated with bone Ca
• Administered
• SQ, IM or intranasal
• May cause nasal mucosal irritation

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Diet

• Well balanced diet
• Multivitamin

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Falls Prevention

• Hospital protocol
• Risk assessment
• Plan

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Exercise

• WALK
• 30 MINUTES A DAY AT LEAST 3X/WEEK

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Pain Management

• Spinal fractures
• Drug therapy
• NSAIDs
• Muscle relaxants
• Orthotic devices

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PREVENTION IS THE BEST TREATMENT
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Pagets Disease

• A slowly progressive metabolic bone disease
  characterized by an initial phase of excessive
  bone resorption, followed by a reactive phase of
  excessive abnormal bone formation
• Cause
• Unknown
• Early viral infection
• Genetic tendency

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• Pathophysiology
• Characterized by an osteoclastic phase of
  excessive bone resorption that is followed by an
  osteoblastic phase in which there is excessive
  abnormal bone formation
• New bone is fragile and weak resulting in
  deformities
• Bone marrow is frequently replaced by loose
  fibrous tissue increasing vascularity
  (hypervascular bone)
• Early stages may be asymptomatic but when pain
  develops it is severe and persistent

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• Incidence
• In US affects 3 of people 50 years
• Males slightly females
• Found most often in England, Australia
• Complications
• Bone pressing on cranial nerves may result in
• Vertigo
• Hearing loss
• Blindness
• Hypertension
• Congestive heart failure
• Hypercalcemia
• Fractures
• Renal calculi
• Wadling gait (softening of pelvic bones)
• Gout
• Pain

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• Assessment
• Physical
• 80 asymptomatic
• Persistent severe bone pain intensified with
  weight bearing
• Cranial enlargement (? hat size)
• Kyphosis, bowing of tibia and femur (? height)
• Pagetic sites that are warm and tender
• Pagetic fractures
• Hearing loss
• Signs of congestive heart failure
• Skin may be flushed and warm

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• Diagnostic Studies
• Lab
• Alkaline phosphatase ?
• Radiographic
• Show increased bone expansion and density in
  affected areas
• Bone scan shows increased absorption of
  radioisotopes
• Bone biopsy

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• Medical Treatment
• Symptomatic and supportive
• ASA, NSAIDs
• Calcitonin and alendronate (Fosamax)
• Retard bone resorption and decrease bone lesions
• Surgical Treatment
• Reduce pathologic fractures
• Relieve neurologic impingement
• Complications
• Osteogenic carcinoma

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