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For further information, see CMDT Part 26-16: Osteoporosis

Key Features

Essentials of Diagnosis

  • Fracture propensity of spine, hip, pelvis, and wrist from depletion of bone matrix with subsequent demineralization

  • Asymptomatic until a fracture has occurred

  • Serum PTH, calcium, phosphorus, and alkaline phosphatase usually normal

  • Serum 25-hydroxyvitamin D levels often low as a comorbid condition

General Considerations

  • Causes over 1.5 million fractures annually in the United States, most commonly vertebral fractures, followed by hip fractures (300,000 annually) and pelvic fractures

  • Most common causes

    • Aging

    • Sex hormone deficiency

    • Alcoholism

    • Smoking

    • Long-term proton pump inhibitor therapy

    • High-dose glucocorticoid administration

    • See Table 26–9

Demographics

  • Clinically evident in middle life and beyond

  • Develops frequently in hypogonadal men

  • In the United States, at least 20% of men and women over age 50 years have one or more fractured vertebrae

  • White women aged ≥ 50 years (who do not receive estrogen replacement) have a 46% risk of sustaining an osteoporotic fracture during their lives

Clinical Findings

Symptoms and Signs

  • Usually asymptomatic until fractures occur

  • May present as back pain of varying degrees of severity or as spontaneous fracture or collapse of a vertebra

  • Loss of height common

  • Fractures of femoral neck and distal radius also common

  • Once osteoporosis is identified, careful history and physical examination are required to determine its cause

Differential Diagnosis

  • Rickets in childhood (eg, consequence of vitamin D deficiency)

  • Osteomalacia in adulthood (inadequate mineralization of existing bone matrix [osteoid])

  • Plasma cell myeloma (formerly multiple myeloma)

  • Metastatic cancer

  • Paget disease of bone

  • Renal osteodystrophy

Diagnosis

Laboratory Tests

  • In cases of primary osteoporosis, the following tests are normal:

    • Blood urea nitrogen

    • Creatinine

    • Albumin

    • Serum calcium

    • Phosphate

    • PTH

  • Alkaline phosphatase

    • Usually normal but may be slightly elevated, especially following fracture

    • Hypophosphatasia may be present when value is low (< 40 units/L in adults)

  • Complete blood count is obtained and is usually normal

  • For patients with anemia, further screening is required, including a SPEP to screen for myeloma and intestinal malabsorption screening, where indicated

  • Vitamin D deficiency is very common

  • Testing for thyrotoxicosis and hypogonadism may be required

  • Screen for celiac disease with serum IgA anti-tissue transglutaminase antibodies

Imaging Studies

  • Radiographs of spine and pelvis may show demineralization; in skull and extremities, demineralization is less marked

  • Radiographs of spine may show compression of vertebrae

  • Dual-energy x-ray absorptiometry (DXA) is quite accurate and delivers negligible radiation

  • Osteoporosis: bone densitometry T score ≤ –2.5; osteopenia: T score ≤ –1.0 to –2.5

  • Quantitative CT delivers more radiation but is highly accurate

Diagnostic Procedures

  • Fracture Risk Assessment Tool (FRAX)

    • Developed by the World Health Organization to better predict an individual's 10-year ...

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