Fact Sheet Number 107
Chemistry Panel
- CHEMISTRY (CHEM) SCREEN
- THE ELECTROLYTES
- KIDNEY FUNCTION TESTS
- LIVER FUNCTION TESTS
- OTHER BLOOD CHEMISTRY TESTS
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A large part of your laboratory report is results of the chemistry
screen. These tests measure various chemicals in your blood to
see whether your body is working correctly. See Fact
Sheet 106 for information on the Complete Blood Count and
Fact Sheet 108 for information on
blood glucose (sugar) and cholesterol tests.
Laboratories have different “reference ranges” or
normal values for the results of each test. Most lab reports show
the normal range and highlight any test results outside the normal
range. For more information on laboratory test results, see MEDLINEplus
online at http://www.medlineplus.gov/
The mineral calcium is a major component of bones and
teeth. Calcium is also needed for nerves and muscles to work properly,
and in chemical reactions in the cells. The body controls the
amount of calcium in the blood. However, the amount of protein
in the blood can affect calcium test results (see albumin). The
most common cause of low calcium test results for people with
HIV is low protein levels due to malnutrition or wasting. Abnormal
calcium levels can indicate digestive problems.
Phosphorus, like calcium, is a major component of bones.
Low levels of phosphorus for a long period of time can cause damage
to bones, nerves and muscles. High phosphate levels are most often
due to kidney failure.
Glucose is sugar, which is broken down in the cells
to provide energy. See Fact Sheet 108
for more information on blood glucose tests.
The electrolytes are related to fluid balance in your cells. They
are especially important if you become dehydrated or have kidney
problems.
- Sodium levels indicate your balance of salt and water.
They also are a sign of the functioning of your kidneys and adrenal
glands. Abnormal blood sodium levels often indicate that blood
volume is too low (due to dehydration) or too high. They can
also occur when the heart is not pumping blood normally, or when
the kidneys are not working properly.
- Potassium affects several major organs including the
heart. Potassium levels rise in kidney failure, and may be abnormal
due to vomiting or diarrhea.
- Chloride levels often go up and down along with sodium
levels. This is because sodium chloride, or common salt, is a
major component of blood.
- Bicarbonate or CO2 measures a buffer system
in the blood. A normal CO2 level keeps the blood acidity at the
correct level.
TESTS
The basic kidney function tests are blood urea nitrogen (BUN)
and creatinine. Abnormal levels of phosphorus, sodium or uric
acid can also be caused by kidney problems.
Blood Urea Nitrogen (BUN) is nitrogen in the blood.
This is a waste product that is normally removed by the kidneys
in the urine. High BUN levels can be due to a high-protein diet,
dehydration, or kidney or heart failure.
Creatinine is a waste product of protein digestion and
a measure of kidney function. High levels are usually due to kidney
problems. Doctors use the creatinine level as most direct sign
of how well the kidneys are removing waste products from the body.
TESTS
The lab tests called “liver function tests” actually
measure the levels of enzymes found in the liver, heart, and muscles.
Enzymes are proteins that cause or increase chemical reactions
in living organisms. High enzyme levels can indicate liver damage
caused by medications, alcohol, hepatitis, or recreational drug
use.
Different patterns of these enzymes – when some are elevated
and others are normal – can help your doctor identify specific
health problems. Laboratory tests include:
- ALT (alanine aminotransferase), formerly called serum
glutamate pyruvate transaminase or SGPT)
- AST (aspartate aminotransferase), formerly called
serum glutamic-oxaloacetic transaminase or SGOT)
- Bilirubin (a yellow fluid produced when red blood
cells break down). Note: The antiviral drug indinavir (Crixivan®)
can increase bilirubin.
- Alkaline Phosphatase
- GGT (gamma glutamyl transpeptidase)
- LDH (lactic dehydrogenase)
TESTS
Uric Acid comes from the breakdown of DNA (genetic
material in the cells). It is normally removed by the kidneys.
High levels of uric acid are fairly common. Very high levels can
be caused when the kidneys are unable to remove uric acid from
the blood or by leukemia or lymphoma.
Albumin is the major protein in the blood. It maintains
water balance in the cells, carries nutrients to the cells and
removes waste products. Low albumin is generally a sign of nutrition
problems.
Because albumin carries so many substances in the blood, low
albumin levels can cause incorrect low results for other laboratory
tests, especially calcium or testosterone.
Globulin measures the protein in antibodies produced
by the immune system. HIV infection causes an abnormally high
level of globulin.
Sedimentation Rate or Sed Rate measures how quickly
red blood cells settle in a tube of blood. A high sed rate indicates
some type of inflammation. However, the sed rate does not indicate
whether the inflammation is long-term, like arthritis, or is due
to the body fighting an infection.
Revised April 30, 2002
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