S. TANTAWY M.D. S. TANTAWY M.D.

The
The Easy
Easy Way
Way To
To
Diagnose
Diagnose Osteoporosis
Osteoporosis
By
By
S.
S. TANTAWY
TANTAWY M.D.
M.D.
Osteoporosis
• Osteoporosis
is
a
skeletal
disease
characterized by low bone mass and
microarchitictural
deterioration
of
bone
tissue leading to enhanced bone fragility and
a consequent increase in fracture risk.
• Bone loss is inevitable and is part of the
normal aging process. It is greater in
trabecular than in cortical bone and occurs at
a linear loss of 1.2%per year from the age of
30.
Bone
Bone Mass:
Mass: What
What is
is normal?
normal?
• What is dividing line between normal and
abnormal:
Many
researchers
(Independently)
established that elderly women are at
risk fracture when their peak bone
mass in a given area is reduced by
20% to 30%or more compared with
their
peak
bone
mass
(PBM)
(PBM)­35 to 40years of age .
Factors
Factors affecting
affecting PBM
PBM and
and clinical
clinical
risk
risk factors
factors for
for osteoporosis:
osteoporosis:
Genetic:
Genetic:
Race
Race (white,
(white, Asian)
Asian) Sex
Sex (female)
(female) Family
Family
history.
history.
Nutritional:
Nutritional: Low
Low Ca
Ca intake
intake ,High
,High caffeine
caffeine and
and High
High
alcohol.
alcohol.
Life
Life style:
style:
Low
Low body
body weight,
weight, cigarette
cigarette consump.
consump. and
and
Low
Low physical
physical activity.
activity.
Drugs:
Drugs:
Corticosteroids,
Corticosteroids, anticoagulants,
anticoagulants,
anticonvulsants,
anticonvulsants, Lithium
Lithium &
& methotrexate
methotrexate
Endocrine:
Endocrine: Early
Early menopause
menopause &
& late
late menarche.
menarche.
Evaluation
Evaluation Of
Of Bone
Bone Mass
Mass
• I­Radiological
II­Biochemical
1­Radigrametry
2­Single and Dual photon absorptiometry
3­Single and Dual photon X­ray
absorptiometry
4­Neutron activation analysis.
5­Quantitative computed tomography.
6­Quantitative ultrasound.
7­High resolution MRI.
1­Radiogrametry
Radiographic
Radiographic
techniques
techniques are
are
subject
subject to
to a
a range
range
of
of problems
problems for
for
example;
example; variation
variation
in
in beam
beam quality,
quality, film
film
processing
processing and
and
scattered
scattered radiation.
radiation.
2­Single and Dual photon
absorptiometry
Based on photons emitted from a
radioactive source (I­125) or Gd­153
in dual photon absorptiometry.
SPA has a precision of 2­3%&
accuracy 5­6%
D.Ph.A. has a limited precision 2­4%
and accuracy error is up to 9%
Precision & Accuracy
• Precision : is the reability of
method for repeated tests. It is
the ability to obtain the same
result
from
repeated
measurements.
• Accuracy: is the reability of
actual measurements by other
methods.
3­ Single Energy X­Ray
Absorpiometry
• Both SPA and SEXA are based on the
same principal except that the photon
source in SEXA is an X­Ray system.
• It is used to measure bone density at
the forearm only. The arm is placed in
water bath.
• Scanning time is about 4­5m…Results
are expressed in BMC or BMD in gm/cm2
• Precision is 1% while accuracy error is
3%
Dual Energy X­Ray
Absorpiometry (DEXA)
• Physical principals of DEXA are similar
to DPA except that a low dose X­ray
tube replaces the radioactive Gd­153
as a source of photon.
• Scan time is few second for the
forearm and about 4 min. for lumbar
spine with precision 0.5 % and
accuracy 3­5%
Interpretation of
DEXA
In order to interpret BMD results in an
individual patient. It is essential to
have appropriate race and sex
matched BMD reference range. The
patient
results
can
then
be
expressed as a standard deviation
(SD) (Z score), percent percentile of
expected for age and sex, or as
(SD)(T score) percent or percentile
of age matched peak bone mass .
The WHO,1994 has
defined
“Osteopenia” as T­score between ­1
and ­2.5.
“Osteoporosis “ as T­score below­
2.5.
Severe osteoporosis as T score
below ­2.5 with fragility fracture.
4­Neutron Activation
Analysis
• This technique depends upon high
energy
neutron
to
activate
calcium­48 to calcium­49…The
decay back to Ca­48 can then be
measured
with
gamma
counter…However this technique
is
only
available
in
few
specialized centers.
5­Quantitative Computed
Tomography (QCT)
• CT is very effective for bone
mineral content measurements at
axial
skeleton.. Also used for
assessment of vertebral fracture
risk, measurement of age­related
bone
loss
follow­up
of
osteoporosis and other metabolic
bone disease.
• CT density is measured in H.U. and
conversion to gm/cm2 is made by
comparing the CT number of the
trabecular
bone
to
that
of
the
compartment of the calibration standard..
The calculated densities for the vertebrae
are averaged and compared to those of
normal population.
• Precision is 2­5% and accuracy 5­20%
6­ Quantitative
Ultrasound
• Ultrasound nowadays is used to
measure bone density either in the
phalanges, os calices or tibia.
• BUA
is determined in logarithmic
scale over the range 0.1­1 MHz…QUS
as there is no ionizing radiation,
portability of the equipment and its
coast effectiveness makes it as an
alternative option for evaluation of
bone mass and may be as screening
tool for osteoporosis.
7­High Resolution MR In
Diagnosis Of Osteoporosis.
• (using
three
dimensional
gradient­ echo sequence) in the
near future MR imaging may be
used to study changes in the
bone density and structure since
MR imaging offer the potential of
providing
information
about
trabecular bone status.
II­Biochemical Markers
• Markers of bone formation include: serum total or
bone specific alkaline phosphatase activity,
serum osteocalin and serum level type I collagen
propeptides.
• OSTEOCALIN is the only sensitive marker of
osteoblastic activity.
• Markers of bone resorption most commonly
is urinary calcium and hydroxyproline their
are elevated in diseases characterized by
bone
turnover
and
are
increased
menopause.
used
level
high
after
Indication For Bone Mass
Measurement
• In
estrogen­deficient
women,
to
diagnose significantly low bone mass
to make decisions about hormone
replacement therapy.
• In patient with vertebral abnormalities
or
radiographic
osteopenia,
to
diagnose spinal osteoporosis to make
decision about further diagnostic
evaluation and therapy.
• In patient receiving long­
term
gluco­corticoid
therapy, to diagnose low
bane
mass
to
adjust
therapy.
• In patient with primary asymptomatic
hyperparathyroidism to diagnose low
bone mass to identify those at risk of
severe skeletal disease who may be
candidate for surgical intervention.
Other potential
Indications
• Universal screening for
osteoporosis prophylaxis.
• Monitoring bone mass to assess
efficacy of therapy.
• Identifying women who are “fast
bone losers” for more aggressive
therapy.
Techniques
Techniques for
for the
the measurement
measurement of
of bone
bone mass
mass
Technique Site Radiogrametry Hand 1 to 2 4 3 to 5 100 Single­photon absorp. Wrist, heel 1 to 3 5 15 10 to 20 Dual­ photon absorp. Spine, hip, total body 2 to 4 4 to 10 20 to 40 5 0.5 to 2 3 to 5 3 to 7 1 to 3 2 to 5 5 to 20 Dual­energy X­ Spine, Ray absorp. hip, total DEXA body Quantitative CT Spine Precision Accuracy Exam. (%) (%) time (min) Radiation dose* (mrem) 10 to 15 100 to 1000 * One chest roentgenogram gives a radiation dose of 20 to
50 mrem, a full dental roentgenogram 300 mrem.
Conclusion:
• Considerable
effort
has
been
expended
in
the
development of methods
for quantitative assessing
of
bone
mass,
its
progression and response
to active therapy carefully
monitored .
• The capability now exists to
evaluate the peripheral , central
or entire skeleton as well as
trabecular bone with a high
degree of accuracy & precision
for determining bone strength
and predicting fracture risk.
• All methods of evaluation of bone
mass had been shortly discussed .
• The
goal
standard
in
DEXA
evaluation of bone mass is to
diagnose osteopenia which has
greater ttt potential i.e possible to
improve bone mass & associated
bone strength.
Clinical Message
Suspect low bone mass
in daughters of women
with osteoporosis
Concentrate on
influencing their life style
Clinical Message
Optimize good nutrition
and eating habits in
adolescent women
Clinical Message
Evaluate teenagers to
ensure a regular and
structured physical
exercise program
Counsel them to avoid a
sedentary lifestyle
Clinical Message
Monitor women with late onset
menarche, irregular cycles and
anovulation / infertility
Emphasize nutrition and exercise
and depending on the etiology
Prescribe low­dose of oral
contraceptives
Clinical Message
How to prevent and treat
osteoporosis
You can prevent osteoporosis
by having calcium rich diet
doing exercises, stop smoking
and reduce your caffeine
intake
Clinical Message
Treatment is easy and
available
Provided the disease is
discovered early
Thank You