Related Conditions
Routine Bone Mineral Density (BMD) Testing

Osteoporosis:
A systemic skeletal disease characterized by low bone mass and micro-architectural deterioration, with a consequent increase in bone fragility with susceptibility to fracture. (W.H.O definition).  Osteoporosis screening is the most common aim of routine DXA scanning which can be determined by comparing a person’s bone density to the bone densities of a large population. In summary, to see how someone may rank compared to an average (ie: above or below) with specific levels indicating one of the following outcomes depending on your age or menopause status:

Males ≥50 / Females ≥menopause Males <50 / Females <menopause
Normal BMD
(T-Score: ≥ –1.0)		 Within expected range for age
(Z-Score: > –2)
Osteopenia (low BMD)
(T-Score: Between –1.0 and –2.5)		 Below expected range for age
(Z-Score: ≤ –2)
Osteoporosis
(T-Score: ≤ –2.5)

Listed below are some of the many sub-conditions which can result in osteoporosis:
Ageing and menopause:

  1. Males: Ageing related testosterone loss
  2. Females: Menopausal estrogen loss
  3. Both cases are associated with lowered bone density
Weight – both low and high

  1. Low weight/stature may not apply sufficient enough skeletal stress to encourage normal bone turnover
  2. High weight/stature may either apply too much skeletal stress so as to outbalance normal bone turnover
  3. Both cases may also preclude other conditions associated with low bone density
Low calcium and vitamin D levels

  1. As calcium forms a significant portion of bone mineral, low availability will be made evident in a person’s bone density results
  2. The hormone Vitamin D has a regulatory effect on calcium absorption, hence low availability will restrict calcium availability
  3. Both cases of low calcium and vitamin D may be diet related but more often related to other factors such as hormonal conditions
Life-style factors: smoking, alcohol abuse, lack of exercise

Smoking: Although a chemical link between tobacco and low bone density is yet to be determined, the correlation between the two is high enough for smoking to be classified as a risk factor. Alcohol: Excessive drinking can affect pancreatic calcium absorption, increase parathyroid hormone activity and interfere with cells responsible for bone remodeling. Lack of exercise: little or no bone stress can lead to under-stimulation of cells responsible for normal bone turnover. Furthermore may result in destructive cell activity overbalancing remodeling cell activity.
Use of corticosteroids
Corticosteroids which are commonly prescribed for various allergies and conditions, unfortunately have an affinity for interfering with normal bone remodeling cell function.
Genetic factors (family history, race)
Similar to many other conditions, family history and racial traits, on both a behavioral or genetic level can present with correlations to low bone density, hence these factors are duly noted by screening professionals.
Thyroid Disease

  1. Overactive thyroid (hyperthyroidism): initiates a quickening of the bone turnover process to the point where bone remodeling cannot keep up with the rate of bone breakdown.
  2. The hormone Vitamin D has a regulatory effect on calcium absorption, hence low availability will restrict calcium availability
  3. Underactive thyroid (hypothyroidism): is the extreme opposite of the above, hence synthetic thyroid hormones are prescribed. If such medications are abused or taken for long durations, the effects of hyperthyroidism described above can then initiate.

Related Conditions
Body Composition Analysis (BCA)

Listed below are some of the conditions that BCA can greatly assist with diagnosis and treatment but is not widely used for. Allied Health Care Professionals should consider adding a BCA scan as part of best practice care for patients.

Anorexia/Malnutrition:
Anorexia is a psychological condition often associated with body image dissatisfaction which can be broken down into two main types:
1. Nervosa: Associated with binge eating/purging and excessive caloric restriction
2. Athletica: Associated with unhealthily obsessive compulsive exercise habits

Body composition analysis can be a helpful method of monitoring musculoskeletal effects and therapeutic progression of anorexia by weighing up a subject’s muscle, fat and bone mass against population averages and monitoring intervention effects over time from the inside out.

When used as a part of a medically guided psychological approach, body composition analysis has the potential to guide improvements in a far clearer manner than traditional methods such as the use of body mass index (BMI).

For more information on anorexia please visit www.eatingdisorders.org.au
Obesity:
As current definitions of obesity tend to revolve around the use of body mass index (BMI) which classifies based on a person’s weight divided by their squared height, this condition can be difficult to clarify given that BMI can often miss-classify those with abnormally though advantageously high amounts of muscle as ‘obese’.

The use of body composition analysis where available can be a helpful tool both alongside and as a replacement to BMI in the aim of monitoring clearer indications of abnormally high fat levels (through results such as body fat % population average comparisons), compartmentalizing fat/muscle mass and being able to monitor rates of change for each area over time.

BMI can still be used as a contrast result to indicate cases of healthy state obesity, whereby one may present as obese on the BMI scale though have other body composition indications suggesting a state of composition related healthiness.

For more information on obesity please visit www.obesityaustralia.org
Lipodystrophy:
Lipodystrophy can both stem from genetic and acquired sources (such as with HIV) but in both cases involves an abnormality in the way a body stores and distributes fat. In many cases the subcutaneous layer (layer of fat just beneath the skin) is the most affected area, hence the condition can be quite recognizable. Lipodystrophy can lead to an array of other conditions such as polycystic ovarian syndrome, pancreatitis and liver cirrhosis.

As a part of a medically guided approach lipodystrophy in certain populations can be screened using body composition analysis to help derive fat distribution ratios between the trunk and limbs which is especially useful in the case of HIV management amongst other conditions.

Sarcopenia:
The European Working Group on Sarcopenia in Older People defines sarcopenia as a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength with a risk of adverse outcomes such as physical disability, poor quality of life and death.

From this established working definition, a diagnosis of sarcopenia needs to incorporate both:

  1. a structural component which can be derived from a body composition result known as appendicular lean height (compares height to lean mass in the limbs).
  2. a functional component involving tests of gait speed and grip strength to cover both upper and lower body function.
Cystic Fibrosis (CF):
CF involves an abnormally functioning exocrine (duct secreting) system leading to impaired pancreatic and respiratory function. CF is genetically obtained which requires both parents to be carriers in order for a child to be born with the condition.

As malnutrition is an associated side effect of CF requiring enzyme supplementation in order to allow the body to properly process carbohydrates and proteins, adequate monitoring of muscle retention may be a helpful tool in tracking responses to supplementation and pulmonary interventions in comparison to traditional classification criteria involving the use of BMI.

Body composition analysis enables the compartmentalization of muscle mass, when used alongside other measures such as height can derive better indicators of supplementation driven metabolism compared to traditional measures. Population average comparisons of composition analysis derived lean body mass indices have also been suggested as holding a stronger association with lung function than commonly used BMI based methods.

For more information on Cystic Fibrosis Please visit www.cysticfibrosis.org.au

Diabetes:
In simple terms, diabetes involves an abnormality in the way a body processes glucose – our main energy source. This is commonly due to a partial (type 2 diabetes) or complete deficiency (type 1 diabetes) of the hormone insulin which functions as a glucose processing mechanism for muscle cells.

The condition can pose an array of metabolic and cardiovascular health risks for which body composition analysis contains clinically valuable information to classify and monitor with. A typical example involves screening measurement and intervention related reduction monitoring of visceral fat (fat inside the rib cage) which has an association with the development of type 2 diabetes.

For more information on diabetes please visit www.diabetesaustralia.com.au

Paget’s Disease:

Paget’s disease is a chronic bone condition affecting remodeling at the microscopic level resulting in the rate of bone remodeling outbalancing bone breakdown – this leads to abnormally enlarged bone growths with impaired structural integrity compared to bone with a normal turnover rate.

Older Caucasians tend to be at higher risk of developing Paget’s disease, affecting males slightly more than females with the exact cause remaining under investigation. Bones more commonly at risk include the skull, spine, pelvis, femur and humerus.

Osteomalacia:

Often as a result of Vitamin D deficiency, Osteomalacia entails a bone softening effect, subject to both bending and breaking, as a direct result of poor calcium absorption and bone mineralization.

As Vitamin D uptake can also be affected by various conditions such as Celiac or diseases of the liver and kidneys, treatments can vary but will often involve Vitamin D and calcium supplementation. As sun exposure is an important source of Vitamin D, world regions with cooler climates or with traditional body covering practices are often at risk.

Osteogenesis Imperfecta:

A genetically obtained disorder drawing from a collagen mutation, OI – otherwise known as ‘brittle bone disease’ results in a malformed skeletal structure often accompanied by blue tinting in the eye sclerae and opal tinged teeth.

As there is currently no cure for this genetic condition, prosthetic (metal) reinforcements and treatments such as bisphosphonate therapy are amongst the most common courses of action.

Learn more about bone density conditions: