Why it is important to know your ALT – A conversation
with Dr. Rajiv Jalan MD, FRCP, FRCPE,
PhD
What is it?
The ALT is a protein manufactured in the liver
which participates in metabolism. The term ALT refers to
alanine-amino transferase.This
protein is an enzyme which participates in modifying aminoacids,
the building blocks of proteins. The ALT is made predominately in
the liver and therefore alterations in the serum ALT can be
directly related to disturbances of liver structure and
function.
Is the serum ALT hard to
measure?
It is straightforward to have ones blood
sample tested for a serum ALT, it only requires obtaining a blood
sample. The serum ALT is easily measured in laboratories
throughout the world. The methodology may vary from laboratory
to laboratory, making direct comparisons of the absolute serum ALT
value difficult, but all laboratories have a normal range for men
and women.
What does an elevated serum ALT
reflect?
The ALT is manufactured within liver
cells. Elevations in the serum ALT reflect alterations in the
structure and function of the liver. Damaged liver cells release
ALT into the blood stream where it can then be measured. The serum
ALT, therefore, reflects damage to liver cells, liver injury, and
underlying liver disease.
Why should I know my serum
ALT?
We should all be aware of our health.
Unfortunately, unlike diseases affecting other organs, injury to
the liver can be silent. Patients may not have any symptoms and the
ALT can be elevated for years before one is aware of an underlying
liver disease. When one develops symptoms from liver disease, it
usually reflects advanced damage to the liver. Once significant
damage to the liver has occurred, therapies other than liver
transplantation, may not be very beneficial. Recent studies show
that a persistently elevated abnormal ALT is associated with higher
mortality than standardised mortality. Therefore, making the
diagnosis of a liver disease early in its course can be very
beneficial in regards to receiving specific therapies and modifying
lifestyle.
My doctor also measures other blood
tests. What are they and is the serum ALT the best
test?
The liver is a complex organ with a variety of
essential functions for the body. It participates in metabolism,
produces bile, and generates proteins secreted into the blood, so
your doctor may measure compounds associated with all of these
liver functions. All of those tests are frequently measured
in a battery of tests referred to as a “liver panel.”
Depending upon the type and nature of the underlying liver injury
and therefore the liver disease, changes in the magnitude of the
various components of this panel provide meaningful information to
your physician. However, if one simply wants to know whether
one has liver wellness or may have an underlying liver disease, the
ALT is likely the most sensitive test for the vast majority of
liver illness.
Is there a direct correlation between
the magnitude of the serum ALT elevation and the severity of the
underlying liver disease?
Although there can be a relationship between
the magnitude of elevation in the serum ALT and the severity of the
abnormalities in liver structure and function, this relationship is
not absolute. Patients with advanced scarring of the liver
may have significant liver dysfunction despite only mild elevations
of the serum ALT. Therefore, any elevation of the serum ALT
should be taken seriously and one should seek appropriate medical
care to determine the cause.
What are some common causes of an
elevated serum ALT?
Perhaps the most common cause in the North
American population is fat accumulation within liver cells.
Fat can accumulate anywhere in the body, but its accumulation in
the liver cells is toxic to the liver. In particular,
patients who are above their ideal body weight, have diabetes, or
elevations in their blood lipids, may be at risk for having fat
within the liver. The serum ALT is a common approach to
determine whether one may have fat in the liver and if it is
injurious to this organ. Other common causes of an elevated
serum ALT include excessive consumption of alcohol, infection by
chronic hepatitis viruses such as hepatitis B and C, toxicity from
pharmaceutical medications, a genetic liver disease associated with
an excess accumulation of iron in the liver, and autoimmune liver
diseases. The latter are a variety of liver diseases in which
the body’s immune system inflicts damage on ones own
organ.
I have an elevated ALT. What should I
do?
If you have an elevated ALT, you should seek
medical attention. The vast majority of primary care
physicians and specialists in gastroenterology and hepatology, can
perform the necessary testing to determine the cause of an elevated
serum ALT.
How often should I have my serum ALT
measured?
Like the serum cholesterol and blood glucose
tests for elevated cholesterol and diabetes, respectively; one
should have the serum ALT measured repeatedly and regularly over
time. A conservative approach would be to have ones serum ALT
measured on an annual basis during the annual physical
examination.
Information provided
by Dr
Rajiv Jalan.
General Disclaimer
This page is designed for educational purposes only and is not
engaged in rendering medical advice or professional services. The
information provided through these pagess should not be used for
diagnosing or treating a health problem or a disease. It is not a
substitute for professional care. If you have or suspect you may
have a health problem, you should consult your health care
provider.