The best indicator of hepatotoxicity is an increase in certain liver
enzymes that circulate in the bloodstream. The most important enzymes
are AST (aspartate aminotransferase), ALT (alanine aminotransferase),
alkaline phosphotase, and bilirubin. These four enzymes are normally checked
as a part of a "chem screen," a panel of tests that your doctor
probably orders every time you have blood drawn to check your T-cells
and viral load.
To learn more about these and other important liver enzymes that are
usually checked as part of your regular "chem screen," click
here:
Understanding Your Chem-Screen (CS) Test
If you or your doctor has any reason to suspect that a drug you are taking
has been causing liver injury, then a blood test should be performed.
It is always best to detect hepatotoxicity in its early stages so that
steps can be taken to prevent it from getting worse and to allow the liver
to heal.
Most of the time, hepatotoxicity takes several months or years to develop
and usually begins with mild increases in either AST or ALT that progresses
to more serious increases. Generally speaking, if your AST or ALT levels
are elevated but are no higher than five times the normal range (e.g.,
AST above 43 IU/L but below 215 IU/L or ALT above 60 IU/L but below 300
IU/L), you have mild-to-moderate hepatotoxicity. If your AST is higher
than 215 IU/L or your ALT is above 300 IU/L, you have severe hepatotoxicity,
which can lean to permanent liver damage and serious problems.
Fortunately, as stated above, the vast majority of doctors order chem
screens on a regular basis (every three to six months) and are usually
able to catch mild-to-moderate hepatotoxicity (which is often reversible)
before it progresses to severe hepatotoxicity. However, some drugs, such
as Ziagen® (abacavir) and Viramune®
(nevirapine), can result in an allergic reaction in the liver that can
cause liver enzymes to increase sharply soon after the medication is started.
In turn, it is very important that your doctor check your liver enzymes
every two weeks for the first three months if you begin taking either
of these medications.
Increased liver enzymes can rarely be felt. In other words, you may not
have any physical symptoms, even if your liver enzymes are elevated. Thus,
it is very important that you and your doctor monitor your liver enzymes
on a regular basis using blood tests. However, symptoms can occur in people
with severe hepatotoxicity and these symptoms are very similar to those
associated with viral hepatitis (e.g., hepatitis B or hepatitis
C). Symptoms of hepatitis include:
- anorexia (loss of appetite)
- malaise (feeling unwell)
- nausea
- vomiting
- light-colored stools
- unusual tiredness/weakness
- stomach or abdominal pain
- jaundice (yellowing of the skin or whites of the eyes)
- loss of taste for cigarettes
If you are experiencing any of these symptoms, it is very important that
you speak with your doctor or another health-care provider.
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