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Part 1of BP's Liver Series
Under-rated and Under Pressure
Part 2 in our liver series, BP gives the liver the once over: what does it do, how does it do it - all giving a good starting point from which to understand other 'liver issues' such as Hepatitis B, C, cirrhosis, fibrosis etc. (from issue 9)
Part 2 of BP's Liver Series
The
LIVER FUNCTION TEST (from issue 1)
You know the saying 'Knowledge is power?' Learning
a bit about how your liver works, what it needs to function well and understanding
what your results actually mean to you, allows you to be a bit more forearmed
when treatment decisions come your way. For the 2nd in this series we
thought we should start with deciphering the liver function test.It
is usually the first test you will have when information about your liver
is required. It is helpful to understand these results, they are part
of your liver's 'big picture' and by comparing them over time you may
be able to find out whether lifestyle changes are benefiting (or not)
your liver.
THE ROLE OF THE LIVER
The role of the liver is to keep the body's complex internal chemistry
in balance. It takes raw nutrients from our digestive system (in the form
of carbohydrates, so they can be stored and sent to different parts of
our body in the right form and quantity. The liver regulates the level
of sugars in our blood and manufactures bile (which breaks down fats in
our stomach). It also helps remove toxins, drugs and hormones from our
bloodstream.This brief explanation does the liver little justice - it
actually carries out over 1,500 complex biochemical functions. Perhaps
it is because the liver is so important, that up to a certain point, like
a lizard's tail, it can rejuvenate itself.
WHAT ARE LIVER FUNCTION TESTS?
A liver function test (LFT) is a blood test that gives an indication of
whether the liver is functioning properly. The test is also very useful
to see if there is active damage in the liver (hepatitis) or sluggish
bile flow (cholestasis). Liver function tests measure the amount of particular
chemicals in the blood. This gives a gauge of possible damage to liver
cells- damage that can be caused by many things including HCV. So a more
correct term for a liver test would actually be a liver dysfunction test.
It's important to remember that diagnosis of liver disease depends on
a combination of patient history, physical examination, laboratory testing,
biopsy and sometimes imaging studies such as ultrasound scans. Diagnosis
of hepatitis C usually also involves antibody tests or PCR tests.
People reading this should keep in mind that abnormalities within liver
tests don't necessarily point to specific diseases. Only a physician who
knows all the aspects of a specific case can reliably make a diagnosis.
So what are the substances measured in an LFT blood test and what is so important about them?
Total
protein Is
simply a combined measure of the concentrations of proteins in the blood.
This information can provide clues to several diagnostic possibilities.
There are two major types of protein: albumin and globulin.
Albumin
Provides a gauge of nutritional status. Can be reduced due to liver damage
and kidney disease. Because albumin is made in the liver, levels tend
to drop with cirrhosis.
Globulin
Describes the specific level of globulin's - which include antibodies.
This measure can be raised when liver cells are damaged due to autoimmune
liver damage or to long standing liver disease of many types, particularly
when cirrhosis exists.
Bilirubin
Is a by-product of the yellowish pigment responsible for jaundice. Bilirubin
levels can be raised due to Diseases, as well as conditions other than
liver disease, e.g. Gallstones. In cases of long term liver illness (chronic
hepatitis), the level usually stays within the normal range until significant
liver damage has occurred and cirrhosis is present. In cases of short
term liver illness (acute hepatitis), elevated Bilirubin levels indicate
the severity of the acute illness.
GGT
Is an enzyme produced in bile ducts that may be raised due to bile duct
illness. The GGT test is extremely sensitive and may be elevated due to
any type of liver disease or by different drugs, including alcohol, even
when liver disease is minimal. GGT levels sometimes rise even in the case
of a normally functioning liver.
Alk phos
Refers to Alkaline Phosphatase, a family of enzymes produced in the bile
ducts, intestine, kidneys, placenta and bones. These levels may rise when
a disease of the bile ducts or bone disorder occurs.
ALT
Is an enzyme produced in hepatocytes (the major type of liver cells) .
ALT level in the blood is increased when hepatocytes are damaged or die-
all types of hepatitis (viral, alcoholic, drug induced etc) cause hepatocyte
damage. Levels of ALT may equate to the degree of cell damage but this
is not always the case, particularly with hepatitis C. An estimate of
cell damage can only be made by liver biopsy.
AST
Is similar to ALT above, but less specific for liver disease because it
is also produced in body muscle cells. It does tend to be higher than
ALT in cases of alcohol related liver disease. (Aust. Hep C Review Aug98)
There are an estimated 200 000 to 400 000 Hepatitis C positive people
in Britain and a possible global infection rate of 170 000 000 people.
(Mainliners 98)
Platelets are the smallest of all blood cells and are involved in promoting
clotting of the blood.- normally a process of healing. In cases of chronic
liver disease where cirrhosis exists, the platelet count can be lowered-
although this can occur due to many conditions other than liver disease.
Adult range or normal range
This figure allows you to compare your various LFT readings with what
is considered to be normal ( these figures will vary slightly for each
laboratory). As shown in our sample LFT result, David Browns ALT reading
of 108 would be over twice the pathology labs upper normal range of 45.
Accessing your medical records? Your rights? Well you do have the right to see your medical records (as passed in the 1990 Access to Health Records Act, backed by the BMA), allowing patients to see their records ON THE CONDITION that it won't harm their mental or physical health. Patients, including children, can ask to see any records made after November 1, 1991, and to have them explained if they are illegible. The process should take a maximum of 40 days (!) and health authorities are allowed to charge £10 plus the cost of copying and sending the records. HOWEVER, for drug users the situation can be a little different. If it is the doctor who writes your scripts who you are asking for your notes, you may well worry that they may take this as an affront, and that you could rock the boat. Yes, sigh, this can be the reality. If so, perhaps it is worthwhile going to a liver specialist (who you should be referred to anyway), keeping things separate from your script. If you have a good relationship with your doctor, why not ask him/her to show/explain your liver function results, or just ask for a photocopy so you can keep your own records. REMEMBER, the health authorities have an obligation to provide information on request in accordance with 1995 Gov. Code of Practice on Openness. Frankly, they need to have a very good reason to refuse you access to your records. It really is time we got used to taking some of our control back.
Introducing the Liver...Part 1
