for Liver and Kidney Disease
Exposure to hazardous or toxic substances
can affect the body in many ways. In general, when chemicals
and other hazardous substances are absorbed, they travel through
the various body systems and can affect a particular organ or
organs, called the “target
organ(s).” Fortunately, the body has mechanisms, mainly in
the liver and kidneys, to process and eliminate many of these substances.
This ability to eliminate toxic substances can reduce the effect(s)
on the target organ(s).
The elimination of toxic substances
is just one of the many functions of the liver and kidneys. For
example, the kidneys maintain the blood volume and regulate the
mineral content in the bloodstream. The liver converts nutrients
into energy, forms proteins and stores carbohydrates. While these
organs can be remarkably resilient in the elimination of toxins,
their other functions can be damaged in the process.
Damage to the kidney and
liver can be acute or chronic. An acute process generally refers
to a relatively short period of time (hours to weeks) between
exposure to the toxin and the onset of symptoms or medical findings.
A chronic process generally refers to a long period of time (years)
between exposure to the toxin and the onset of symptoms or medical
findings. The detection of either an acute or chronic process
or disease can be complex, depending on the type of toxin and
the extent of exposure.
How Do You Detect Liver or Kidney Disease?
Medical screening to detect chronic liver and kidney disease usually
involves a test that measures how well these organs are functioning,
rather than testing for the toxic substance itself. While there
are several reasons for this approach, the main reason is that
many substances that cause chronic disease of the liver and kidney
are difficult to detect in the body.
There are several tests available to detect
abnormalities. Blood tests --- commonly referred to as liver
and kidney function tests --- are among
the most commonly used. In a typical blood chemistry profile,
six liver function and two kidney function tests are done. See
What are Liver Function Tests?
of the liver function tests, with the exception of bilirubin, are
measurements of enzyme levels. These enzymes
are normally present in liver cells, and there is a certain “normal” level
of these enzymes circulating in the bloodstream. When the liver becomes
inflamed or damaged, these enzymes are released into the bloodstream
in abnormal amounts by the damaged cells. This results in elevated
levels in the bloodstream. Bilirubin, another substance commonly
measured in the blood to detect liver disease, is produced from the
breakdown of red blood cells. Again, a normal bilirubin level is
maintained as the liver continually removes bilirubin from the bloodstream
for further processing. If the liver is impaired, however, bilirubin
is not removed, and the level in the bloodstream will rise.
What are Kidney Function Tests?
The kidney function tests do not measure enzymes, but measure breakdown
products of normal body processes. Blood urea nitrogen (BUN) is produced
as a result of protein breakdown. BUN is formed in the liver and
carried via the bloodstream to the kidneys to be eliminated. Creatinine
is a breakdown product of a specific type of muscle protein. It is
formed in certain muscles and is carried via the bloodstream to be
eliminated by the kidneys. If the kidneys become impaired and unable
to eliminate the usual amount of these substances, the BUN and creatinine
blood levels will rise.
|Alanine aminotransferase (ALT)
||Blood urea nitrogen (BUN)
|Gamma glutamic transpeptidase
|Lactic dehydrogenase (LD or
|Alkaline phosphatase (ALP)
What if These Tests are Elevated?
If either a liver or a kidney function test
is elevated, then the next step is to determine what is causing
the elevation. It is important to remember that elevated liver
or kidney tests are not diagnoses in themselves but rather serve
as indicators of abnormal function of these organs.
There are many diseases and conditions that can cause an elevation
of these tests. Some of the more common causes are hepatitis (inflammation
of the liver) from infectious agents such as viruses and substances
such as alcohol. Some common causes of kidney damage include diabetes
and high blood pressure. Kidney and liver damage may also be work-related.
There are certain organic chemicals (such as carbon tetrachloride)
that can cause both liver and kidney disease. Certain metals (lead,
mercury, cadmium and uranium) are known to cause chronic kidney
disease. Since many toxic substances are difficult to detect in
the body, a detailed occupational history is essential for determining
whether kidney or liver disease is work-related.
Liver and kidney function tests, once documented to be elevated,
need to be monitored periodically, depending on the degree of elevation
and the overall medical circumstances. Further tests may be done
to determine more precisely the extent of damage. Besides follow-up
tests, it should be emphasized that if a particular chemical substance,
whether work-related or not, is causing the abnormality in the liver
or a kidney function tests, exposure should be stopped to prevent
further damage to these organs. Workers also need to minimize exposure
to workplace liver and/or kidney toxins if they have kidney or liver
disease of any origin.