ANMU Bone Mineral Density (BMD)

Bone Mineral Density Scan

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Procedure:

You have been referred for a BMD study in which the density of your bones can be determined by using a thin X-ray beam.
The test is also referred to as a DEXA scan (Dual Energy X-ray Absorptiometry).
A BMD study is very useful if you are concerned that your bones are becoming weaker, you are displaying symptoms of osteoporosis, or you have reached the age when preventative screening is necessary.
The study can determine if you have osteoporosis (1), osteopenia (2) or normal bone density (3).
A BMD study can also look at data on soft tissue, bone composition, lean- and fat-tissue mass, and percentage of fat.
Initially a questionnaire needs to be completed, and then your Height and Weight are measured.
You are then required to lie on a bed with your legs elevated on a square cushion.
The X-ray beam will then pass over your lower spine and there is no sensation to this. This takes approximately 5 minutes to complete.
You will then lay your legs flat on the bed and have them rotated inwards. The X-ray beam will then pass over your right or left hip. Again, there is no sensation to this and takes approximately 5 minutes to do.
Occasionally, we require measuring the BMD of your forearm or even your whole body. These can also be done whilst lying on the bed and can take up to 10 minutes to perform.
Usually, measuring the density of your spine and hip is sufficient in determining the density of your bones.
There are many conditions that bring on osteoporosis earlier in life. These are listed below - see "Notes: Conditions...” (4).
A BMD study can take up to 20 minutes to complete and is totally harmless.
You do receive a minuscule radiation dose when having a BMD study.
This dose is less than 0.01mSv ~ 0.0042 times your yearly background radiation (5).
The Federal Government will pay a Medicare rebate for a BMD study only to patients considered at risk of osteoporosis (i.e. with certain medical conditions), those over 70 years or to those already diagnosed with osteoporosis (by a previous DEXA study or QCT scan).

Patient Preparation:

If you are pregnant, trying to fall pregnant or breast-feeding, you must inform our staff.
A BMD Study cannot be performed within 24 hours of having a Nuclear Medicine, PET or MRI scan.
A BMD Study cannot be performed within 7-days of having CT intravenous contrast media or oral contrast media (barium).
If you have had a prior BMD study elsewhere, please bring these results with you.
There is no preparation for a BMD study i.e. eat and drink as normal.
If you are on any medications, please take these as normal.
Wear comfortable clothing and minimise the amount of metal jewellery you have on. All metal objects (zippers, pens, metal buttons, body piercings) bra, plastic, velcro, leather patch, etc… will need to be removed prior to imaging.
Please inform us if you have any prosthetic joints.
Important Note: If you have had Iodine-131 therapy, allow 4-weeks before having this test. Please ring to discuss booking options.

Breast-Feeding Mothers: It is safe to breast-feed after having a BMD study.

Billing:

BMD studies done within 12 months of each other have no Medicare rebate.
BMD studies done within 24 months and certain pre-conditions may have no Medicare rebate.
If unsure of when your last BMD was done with us, please contact us on 9519 9666.
If your BMD was done elsewhere, you will need to know the exact date when this was done and what your pre-conditions were at the time - otherwise Medicare may not reimburse you.
We routinely accept full payment for a BMD study.
You then are required to claim the majority back from the Medicare rebate.
Click here to be directed to the “Payment” section for more information…

Results:

These are usually sent or hand delivered to your doctor.
If you have an appointment to see your doctor within a day or two, it is advisable to wait for the results.
It is important to note that all BMD results should be interpreted with your complete medical history.
For this reason, your referring doctor is the best person to explain these results to you.
Your results are referred to as your T-score and this is based on the bone mineral density of a healthy 20-year-old Australian compared to your own BMD value.

T-Score Values

Normal: Hip T-score is within 1 Standard Deviation (SD) (+1 or −1) of the young adult mean.

Low bone mass: Hip T-score is between 1 and 2.5 SD below the young adult mean (−1 to −2.5 SD).

Osteoporosis: Hip T-score is 2.5 SD or more below the young adult mean (−2.5 SD or lower).

Severe (established) osteoporosis: Hip T-score is more than 2.5 SD below the young adult mean and there have been one or more osteoporotic fractures.

(These BMD categories/values are proposed by the World Health Organization (WHO) and the International Osteoporosis Foundation (IOF))

Z-Score: Compares your BMD to that of a typical individual whose age is matched to yours (rather than a 20 year old). Since a low BMD level is common among older adults, comparisons with the BMD of a typical individual whose age is matched to yours can be misleading. This is why the diagnosis of osteoporosis is based on your T-score (not your Z-Score). A Z-score is very useful for determining whether an underlying disease or condition is causing your bone loss.

Notes:

(1) Osteoporosis – when bones become brittle and fragile from loss of tissue, typically as a result of hormonal changes, deficiency of calcium or vitamin D

(2) Osteopenia – refers to BMD that is lower than normal peak BMD but not low enough to be classified as osteoporosis.

(3) Normal Bone density – is when your BMD is in the range within one Standard Deviation (+1 or −1) of the young adult mean.

(4) Conditions (that can exacerbate osteoporosis): Senile & Postmenopausal osteoporosis, Thyrotoxicosis, Acromegaly, Hypercortisolism, Ovarian Agenesis (Turner's Syndrome), Male Hypogonadism (Klinefelter's Syndrome), Osteogenesis Imperfecta, Adult Hypophosphatasia, Homocystinuria, Marfan's Syndrome, Ehlers-Danlos Syndrome, Menke's Syndrome, Riley-Day Syndrome, Vitamin D Resistant Rickets, Juvenile (idiopathic) osteoporosis, Immobilization, Hepatic Insufficiency, Cystic Fibrosis, Downs Syndrome, Heparin Therapy, Systemic mastocytosis, Chronic Pulmonary Disease, Immunosuppressive Therapy, Rheumatoid Arthritis, Waldenstrom's Macroglobulinemia, Lymphoma, Leukemia, Multiple Myeloma, Hyperparathyroidism, Osteomalacia (in the absence of pseudofractures).

(5) We all receive a yearly background radiation dose ~ 2.4mSv. Radiation dose from a BMD study ~ 0.01mSv = 0.0042 times yearly background dose.

Medicare item numbers, Indications and Frequency for having a BMD Study:

One Service every 24 months (Medicare Item No.: 12306):

Fractures after Minimal Trauma

Monitoring Low BMD (T-score: -2.5 SD ; Z-score: -1.5 SD) proven by densitometry at least 12 months prior.

One Service every 12 months (Medicare Item No.: 12312):

Prolonged Glucocorticoid Therapy (need to be currently taking. Oral >= 7.5mg Prednisone equivalent per day OR inhaled glucocorticoid equivalent to or > 800mcgms beclomethasone dipropionate per day).

Female Hypogonadism

Male Hypogonadism

Cushings Syndrome

Early Menopause (< 45yrs)

One Service every 24 months (Medicare Item No.: 12315):

Primary Hyperparathyroidism

Proven Malabsorption

Hyperthyroidism

Chronic Liver Disease

Chronic Renal Disease

Rheumatoid Arthritis

One Service every 12 months (Medicare Item No.: 12321):

Monitor changes in Osteoporosis Therapy 1 year after change in class of therapy.

One Service every 24 Months (Medicare Item No.: 12322):

Patients aged 70 years or over

One Service every 5 years (Medicare Item No.: 12320):

Patients aged 70 years or over

The following Questions will need to be answered on the day of your BMD study

BMD Questionnaire:

When was your previous BMD?
Has osteoporosis been diagnosed on a previous BMD?
Are you taking any medications and if so, what are they?
If you have osteoporosis, what therapy/treatment are you taking?
How long have you been taking this treatment?
Have you had any fractures that have occurred after minor injury or minimal trauma?
Have you had any surgery on your spine?
Have you had any surgery on your hips?
Have you had any surgery on your wrist/forearm?
Have you had any X-rays or Scans in the last week?
Do you have Rheumatoid Arthritis?
Do you have chronic liver disease?
Do you have chronic kidney disease?
Do you have an Overactive thyroid or parathyroid disease?
Do you have disease associated with bowel malabsorption e.g. Crohn’s or Coeliac disease?
Are you taking any steroid medication e.g. prednisolone, becloforte, becotide?
How long have you been taking these steroids?
Female patients: Have you had amenorrhoea (no periods) for more than 6 months before the age of 45?
Male patients: Are you on treatment for low testosterone levels?
If you’re 40 years or over, has either your mother or father broken their hip?
If you’re 40 years or over, would you drink 3 or more units of alcohol per day?
(1 unit= 285mls = glass of beer / 120mls wine / 60mls aperitif or spirits)
If you’re 40 years or over, do you currently smoke tobacco?
If you’re 40 years or over, are you an insulin dependent diabetic?

To download a copy of this questionnaire, please click here….

NOTE: Questions relating to your medical history are necessary for the calculation of the “FRAX 10 year absolute fracture risk”.

The World Health Organization (WHO) Fracture Risk Assessment Tool (FRAX) computes a 10-year probability of having a major osteoporotic fracture from multiple risk factors (prior fractures, parental hip fracture history, age, gender, body mass index, ethnicity, smoking, alcohol use, glucocorticoid use, rheumatoid arthritis, secondary osteoporosis) including your Hip (femoral neck) T-scores.

Some details of your past medical history are relevant to the reporting of your BMD study.

References:

http://www.niams.nih.gov/Health_Info/Bone/Bone_Health/bone_mass_measure.asp#d

http://www3.gehealthcare.com/en/Products/Categories/Bone_Health/DXA/Prodigy_for_Bone_Health

http://www.rah.sa.gov.au/nucmed/images/posters/DXA_operator_Dose_paper_IBDW_2008.pdf

http://www.ncbi.nlm.nih.gov/pubmed/20839285

http://www.ncbi.nlm.nih.gov/pubmed/20107292

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