Bone Mineral Density (BMD) Test

What is a Bone Mineral Density (BMD) Test?

  • The gold standard for accurately assessing bone mass and predicting fragility fracture risk is Dual Energy X-ray Absorptiometry (DEXA)
  • It is a safe, simple, & painless test to measure your bone mass or bone density
  • This test can diagnose if you have osteoporosis or can predict the likelihood of developing it
  • The patient lies on a table on their back – a small x-ray scanner takes pictures of the spine, hip and forearm areas
  • The radiation from this test is minimal – one/twentieth of a chest x-ray. In simpler terms, it is less than a one-way flight from Toronto to Vancouver!

What is the bone density test used for?

  • To predict risk fracture
  • To confirm a diagnosis of osteoporosis
  • To monitor the rate of bone loss
  • To evaluate effectiveness of treatment

The goal to preventing osteoporosis or a fracture is to be proactive.  One can’t feel or see if the bones are getting porous; the only way to know is by having this gold standard test – the bone density examination to assess your risk for osteoporosis!

Click here for more reasons why you should have a bone density scan
 

Common Risk Factors Include:

  • Age
  • Gender
  • Body size
  • Genetics
  • Menopause related
  • Lifestyle choices
  • Fracture history
  • Medical disorders
  • Drug treatments

MENOPAUSE RELATED:

  • Early menopause before age 45 (natural or surgical )
  • Post menopausal women not on HRT

GENETIC FACTORS:

  • Those of Asian or Caucasian background are at a higher risk than people from other ethnicities
  • Family history of osteoporosis (if one’s mother, father or grandparents have osteoporosis, the risk that they will inherit the disease is increased significantly)
  • Late menarche
  • Loss of height
  • Poor Vision
  • Slender body build (heavier people have more “padding” to support themselves from a fall; larger weight adds more weight bearing stress on the bones stimulating bone turnover; in women, fat tissue provides storage for estrogen)
  • Women (genetically smaller and thinner boned than men, begin to lose bone more rapidly due to menopause, women live longer than men & therefore, are more at risk to age-related decreases in bone mass)

LIFESTYLE CHOICES:

  • Alcohol abuse (>2 ounces / day) – alcohol has no nutrient value and results in direct and indirect bone loss; intoxication leads to an increased risk of falling
  • Caffeine intake (>3 cups / day)
  • Heavy tobacco use (smoking is a hazard to your bones, heart and lungs; women smokers tend to have lower levels of estrogen and as a result, go through menopause earlier)
  • High protein & sodium intake
  • A high protein diet increases the body’s need for more calcium as it causes more calcium to be excreted through the kidneys
  • A low protein diet results in the body’s inability to repair tissues and heal injuries
  • A high sodium diet decreases the body’s ability to use calcium
  • Lack of calcium in the diet
  • Lack of exercise
  • Limited exposure to sunlight
  • Milk intolerance
  • Prolonged immobilization
  • Sedentary lifestyle

MEDICAL DISORDERS:

  • Amenorrhea: absence of menstrual period in child bearing women. It may result from pituitary or ovarian disorders, anorexia nervosa or excessive exercise. These consequently lead to a decrease in estrogen
  • Low Testosterone Levels: in men, this can be due to excessive alcohol consumption or anorexia nervosa. Leads to bone loss.
  • Scoliosis or back / bone pain

OTHER:

  • Age – the longer one lives, the greater the chance of developing osteoporosis; everyone loses some bone as they age but, the rate of bone loss differs in each individual percentage of bone loss increases dramatically (15% to 50%) from a person who is 50 to a person who is in their 70 or 80?s.
  • Fracture of spine, hip, or wrist with minor trauma
  • Osteopenia on plain x-ray

EVALUATE / MONITOR THERAPY FOR OSTEOPOROSIS:

  • Anabolic steroid therapy
  • Bisphosphonates
  • Calcitonin
  • Calcium
    Fluoride
  • Ovarian Hormone Therapy
  • SERMS (Selective Estrogen Receptor Modulators)
  • Vitamin D

MEDICATIONS AND SUBSTANCES THAT MAY CAUSE OSTEOPOROSIS:

  • Alcohol – excess alcohol can lead to liver disease which can impair Vitamin D metabolism
  • Aluminum-containing antacids – used for relief of gas, acidity & minor stomach ailments
  • Anti-convulsants – used for the treatment and control of seizures
  • Barbiturates indicated for generalized tonic-clonic and partial seizures. Toxic effects include drowsiness, ataxia, nystagmus, and learning difficulties
  • Cholestryamine – used for controlling high cholesterol levels
  • Cyclosporin – used during post-organ transplantation and acts as an immunosuppressive drug
  • Glucocorticoids – used for the treatment of rheumatoid arthritis, osteoarthritis, bursitis, asthma, chronic obstructive pulmonary disease, allergic rhinitis, chronic active hepatitis, lupus, psoriasis, severe dermatitis, leukemia, lymphoma & other cancers that require chemotherapy, multiple sclerosis, post-organ transplantation, ulcerative colitis, Crohn’s disease, severe allergic reaction & inflammation of the eyes
  • Glucocorticoid medications affect the remodeling process. In the first five months of oral glucocorticoid therapy, one can lose up to 8% of bone mass; inhaled or injectable steroids are less damaging but does also cause bone loss, particularly when used on a long-term basis with significant dosages. These result in an increase of fractures; the occurrence of fracture is directly proportional to the amount of steroid being administered. Those bones most susceptible to fracture from the action of these medications are the spine, ribs and wrist.

EFFECTS OF GLUCOCORTICOIDS:

  • Osteoclasts are stimulated and bone resorption is increased via various mediators such as cytokines and porstaglandins
  • Calcium absorption in the gut is decreased & may also have increased urinary excretion of calcium
  • Increased protein loss (from bone matrix and muscle)
  • Decrease in osteoblast function and bone formation
  • May suppress hypothalamic-pituitary-gonadal (e.g. estrogen and progesterone) axis and adrenal androgen secretion
  • Patients on these medications for more than 3 months in duration should have a baseline BMD study and be followed closely (e.g. 12 months) if they continue on this therapy.
  • Gonadotrophin Releasing Hormone (GnRH) Analogues – used for the management of endometriosis and infertility
  • Heparin – used for the prevention of blood clots
  • Lithium – This is the most effective drug for manic depression. It can also be used to prevent recurring episodes of depression.
  • Methotrexate – used to treat different kinds of cancers, auto-immune conditions & resistant arthritic conditions
  • Phenytoin (Dilantin) – Anti-epileptic drug used to prevent grand mal seizures. May also be used to prevent seizures before, during and after neurosurgery. Toxic effects include megaloblastic anemia, osteopenia, hirsutism, nausea, vomiting and confusion.
  • Tamoxifen – when used in premenopausal women as a cancer drug; used for reducing recurrence of cancer or progression of the disease
  • Thyroid Hormone (Thyroxine) – used for normal skeletal development

 

Diseases that may cause Osteoporosis:

AUTOIMMUNE DISORDERS:

  • Ankylosing Spondylitis
  • Rheumatoid Arthritis
  • Systemic Lupus Erythematosus (SLE)

CONNECTIVE TISSUE DISORDERS:

  • Bone Marrow Disease – see leukemia, multiple myeloma
  • Multiple Myeloma

ENDOCRINE DISORDERS:

  • Acromegaly
  • Cushing’s Disease
  • Diabetes Mellitus
  • Growth Hormone Deficiency
  • Hyperparathyroidism
  • Hyperprolactinemia
  • Hyperthyroidism (Thyrotoxicosis/Graves disease)
  • Male Hypogonadism
  • Renal Failure

GASTROINTESTINAL DISEASE / NUTRITIONAL DISORDERS:

  • Anorexia Nervosa
  • Celiac Disease
  • Crohn’s Disease
  • Hemigastrectomy
  • Malabsorption Syndromes
  • Parenteral Nutrition
  • Pernicious Anemia

HEMATOLOGICAL DISORDERS:

  • Hemochromatosis
  • Hemophilia
  • Leukemia
  • Systemic Mastocytosis
  • Thalassemia

GENETIC DISORDERS:

  • Congenital Porphyria
  • Hemolytic Anemia
  • Hypophosphatasia
  • Klinefelter’s Syndrome
  • Osteogenesis Imperfecta
  • Thalassemia
  • Turner’s Syndrome

GYNECOLOGICAL DISORDERS:

  • Abnormal Menstruation
  • Polymenorrhea – menstrual cycles of greater than usual frequency
  • Oligomenorrhea – scanty menstruation
  • Hypermenorhea – excessively prolonged or profuse menses
  • Primary – absence of menstruation by age 16; multiple etiology
  • Secondary – absence of menstruation after cycle is established (e.g. in cases of
    pregnancy, anorexia or excessive athletics)
  • Endometriosis

MALIGNANCIES:

  • Lymphoma
  • Multiple Myeloma
  • Metastatic Bone Disease

RENAL DISEASE:

  • Chronic Renal Failure
  • Excess Creatinine
  • Renal Dialysis
  • Renal Tubular Acidosis

RESPIRATORY DISORDERS:

  • Chronic Obstructive Lung Disease (COPD)
  • Sarcoidosis

OTHER:

  • Amyloidosis
  • Epidermolysis Bullosa
  • Hypophosphatasia
  • Idiopathic Scoliosis
  • Osteomalacia
  • Paget’s Disease
  • Multiple Sclerosis
  • Scurvy
  • Severe Liver Disease

IMMOBILIZATION DISORDERS:

  • Cerebral Palsy
  • Multiple Sclerosis
  • Parkinson’s disease
  • Paraplegia
  • Poliomyelitis