The Good Doctor

Tag: osteopaenia

  • Osteoporosis – clinical manifestations

    • fractured spine / wrist (post-menopausal woman)
    • fractured hip (age-related)
    • pain – mid-thoracic, lower back
    • height loss
    • osteopaenia noted on X-Ray (incidental finding)
      • bone mass 3-4 standard deviations below normal
        • late sign
          • ± bone scan

    Note: acute onset of back pain in a woman with a history of compression fracture often indicates  a new fracture.

    Osteoporosis – epidemiology

    The incidence of osteoporosis is rising, even after taking into account for the ageing of the population. The increasing life expectancy has predicted a doubling in the number of hip fractures which will bee seen in the next 50 years.

    • > 50 year-old, life-time risk of osteoporotic fracture is 40% in women and 13% in men
      • women
        • > 45 years – forearm fracture
        • > 65 years – hip fracture (and risk increases exponentially, thereafter, with advancing age)
      • men
        • > 75 years
        • > 85 years – hip fracture (predominately)
    • Risk in Asian, Caucasian >> Black

    Osteoporosis – risk factors

    • hypogonadism
    • glucocorticoid treatment
    • previous fragility fracture
    • low body weight
    • cigarette smoking
    • excess ethanol consumption
    • low dietary Ca++ intake
    • vitamin D deficiency
    • late menarche
    • physical inactivity
    • high caffeine intake
    • maternal history of hip fracture
    • haematological malignancy
      • multiple myeloma, lymphoma, leukaemia

    Although persistent bone loss (hormonal environment) is a feature in most patients with osteoporosis, impaired acquisition of peak bone mass (genetics, Ca++) is responsible for 60-70% of the variance in bone mass at any age.

    ∴ Bone mass measurement will predict the risk of fracture more accurately than calculation of risk factor scores.

    Osteoporotic Fracture – treatment

    1. Analgesia – NSAIDs, paracetamol, opioids
    2. Surgical stabilisation of fracture
    3. Salmon calcitonin (intranasal or subcutaneous) – reduces bone pain
    4. epidural glucocorticoid injection – hospitalised patients
    5. ? admit

    Osteoporotic fracture – prognosis

    • hip fracture can be related to up to 20% 6-month mortality
    • long, complicated rehabilitation
    • reduction in quality of life

    ∴ aggressive strategy to prevent further fracture

    Osteoporotic fracture – pathophysiology

    1.  reduced bone mass
      1. genetics, exercise, + dietary factors → lowered peak bone mass (PBM)
      2. menopause, age (reduced vitamin D, reduced Ca++) → subsequent bone loss
    2. falls – neurological, musculoskeletal, environmental factors

    Peak bone mass (PBM) occurs between 20 and 30 years of age with an increased number of remodelling units with age, favouring a remodelling unit where bone resorption ≠ bone formation.

    Prior vertebral fracture ⇒ 2 x increased Relative Risk for spinal fracture

    Low Bone Mass + prior spinal fracture ⇒ 4 x increased Relative Risk for new spinal fracture

    Osteoporosis – investigations to exclude secondary causes

    • FBC & ESR
    • serum Ca++, PO4, alkaline phosphatase (ALP)
    • liver function tests (LFTs)
    • thyroid function tests (TFTs)
    • serum protein immuno-electrophoretogram (IEPG)
    • urinary Bence-Jones proteins – occasionally normal in myeloma
      • need bone-marrow trephine biopsy to make diagnosis
    • thoracic / lumbar spine lateral X-Ray
    • ± isotopic bone scanning – ? malignancy
    • ± bone biopsy – ? osteomalacia

    Considerations of osteoporosis in men – possible causative factors:

    1. secondary hypogonadism
    2. ethanol
    3. glucocorticoid treatment

    ∴ the following tests may prove useful

    • serum testosterone / gonadotrophins
    • ± serum prolactin

    Osteoporosis – indications for Bone Mineral Density (BMD) assessment

    • recent evidence of osteopaenia and/or vertebral deformity
    • previous fragility fracture of hip, spine, or wrist
    • corticosteroid treatment: > 7.5 mg per day for ≥ 1 year
    • premature menopause: < 45 years old
    • prolonged secondary amenorrhoea
    • primary hypogonadism
    • anorexia nervosa
    • malabsorption
    • primary hyperparathyroidism
    • post-transplantation
    • chronic renal failure (CRF)
    • hyperthyroidism
    • prolonged immobilisation
    • family history of osteoporosis, particularly maternal hip fracture

    Osteoporosis – differential diagnosis (secondary causes)

    • endocrine disorders
      • primary / secondary hypogonadism
      • thyrotoxicosis
      • hyperparathyroidism
      • Cushing’s syndrome
      • hyperprolactinaemia
    • malignant disease
    • connective tissue disorders
      • osteogenesis imperfecta
      • Marfan’s syndrome
      • Ehlers-Danlos syndrome
      • homocystinuria
    • drugs
      • ethanol
      • glucocorticoids
      • heparin
    • others
      • malabsorption / bowel disease
      • post-gastrectomy
      • chronic liver disease
      • chronic renal disease
      • rheumatoid arthritis
      • immobilisation

    Osteoporosis – protective doses of menopausal hormone therapy (MHT)

    • 15 mcg ethinyl oestradiol, oral daily
    • 1 mg 17-β–oestradiol, oral daily
    • 0.625 mg conjugated equine oestrogen, oral daily
    • 50 mcg ethinyl oestradiol, transdermal daily
    • 50 mg oestradiol, over 6 months as implant

    Oestrogen effects

    • 35% Relative Risk reduction of non-vertebral fracture, starting MHT < 60 years old
    • 50% Relative Risk reduction of wrist / hip fracture in younger female
    • less effect on femoral neck than on spine
    • once MHT is ceased, bone loss resumes with little long-term benefit gained

    Monitoring of MHT

    • MHT in patients with secondary osteoporosis
    • newer drugs – e.g.:
      • bisphosphonates
      • calcitonin
      • vitamin D metabolites
      • sodium fluoride

    Osteoporosis – comprehensive management

    • lifestyle
    • activity
    • diet
    • treat risk factors
    • bone mineral density (BMD) measurements
      • + repeat 1-2 yearly