Lactic Acid Dehydrogenase (Blood)
Does this test have other names?
Lactic dehydrogenase, LDH, lactate dehydrogenase
What is this test?
This is a blood test that measures the level of lactic dehydrogenase (LDH) in your
body. LDH is an enzyme, or catalyst, found in many different tissues in your body.
These include your red blood cells, skeletal muscles, kidneys, brain, and lungs. When
your LDH rises, it means that tissues may have been damaged or are diseased.
Why do I need this test?
You may have this test if your healthcare provider suspects you have had a heart attack
or may have tissue damage or disease. If you've already been diagnosed with a specific
disease, you may have this test so your provider can watch your condition and see
whether your treatment is working.
What other tests might I have along with this test?
You may also have a lactate dehydrogenase isoenzyme test. Your total LDH is made up
of 5 isoenzymes numbered LDH-1 through LDH-5. The concentration of each isoenzyme
depends on the tissue. For example, LDH-1 and LDH-2 are found mainly in heart tissue.
LDH-5 is found mostly in the liver.
A higher than normal total LDH means possible tissue damage. Your healthcare provider
might order a lactate dehydrogenase isoenzyme test to find out which tissue is damaged
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
The normal range for total LDH is:
Newborn: 160 to 450 units per liter (units/L)
Infant: 100 to 250 units/L
Child: 60 to 170 units/L at 30° C
Adult/elderly adult: 100 to 190 units/L at 37° C
If your total LDH is higher than normal, it could mean that you have organ or tissue
damage. But total LDH doesn't tell which tissue or organ may be damaged. If all of
your LDH isoenzymes are higher than normal, you could have damage to several organs,
including your heart, lungs, kidneys, and liver. Autoimmune diseases like lupus and
advanced cancers can also cause higher LDH levels.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
If the blood sample is contaminated or your red blood cells are broken, your LDH will
Anesthetics, aspirin, narcotics, and certain other medicines can raise your LDH. Medicines
with ascorbic acid (vitamin C) can decrease your LDH levels. Alcohol also can affect
your LDH levels.
How do I get ready for this test?
You don't need to prepare for this test. Be sure your healthcare provider knows about
all medicines, herbs, vitamins, and supplements you are taking. This includes medicines
that don't need a prescription and any illicit drugs you may use.