Lactate dehydrogenase test
LDH test; Lactic acid dehydrogenase test
Lactate dehydrogenase (LDH) is a protein that helps produce energy in the body. An LDH test measures the amount of LDH in the blood.
Do you feel tired and listless? Do you find your mind drifting during the day? Do you get dizzy or short of breath whenever you climb the stairs? There are a few possible reasons for the way you feel, but you could have anemia. You could even have anemia without noticing any symptoms at all. Anemia is a problem with hemoglobin, a substance in red blood cells that carries oxygen throughout your body. Without enough hemoglobin, your heart and other organs can't get the oxygen they need to work. When your organs slow down, you slow down and you start feeling tired and listless. Many different health conditions can cause anemia, from heavy blood loss during a woman's period, to pregnancy, to an underactive thyroid gland. Healthy red blood cells are made in your bone marrow, the soft tissue in the middle of your bones. Any disease that damages blood marrow, such as lymphoma or leukemia, can also affect your red blood cell production. Anemia can also be caused by an immune system problem that damages red blood cells, or surgery to the stomach or intestines. How do you know if you have anemia? You may feel tired, dizzy, and have trouble concentrating. You may get sick more often. People with anemia often complain of chest pain, headaches, or shortness of breath. Your skin might look pale, like you haven't seen the sun for months. Because these can also be symptoms of other conditions, your doctor will confirm that you have anemia by taking a blood test to check your red blood cell count and hemoglobin level. Blood tests can also look for problems that may be causing your anemia, such as a vitamin or iron deficiency. If you are anemic, it's very important to treat it. When your body isn't getting enough oxygen, it can starve vital organs like your heart. This can lead to a heart attack. How you treat anemia really depends on the cause. If the problem is with your bone marrow, you may take a medicine called erythropoietin, which will help your bone marrow make more red blood cells. If the problem is a vitamin or mineral deficiency, your doctor may prescribe iron, vitamin B12, or folic acid supplements. Or, you may need a blood transfusion to replace damaged red blood cells with healthy ones. How well you do really depends on what's causing your anemia. Call your doctor if you have any symptoms like fatigue or shortness of breath. Once your doctor can find and treat the cause of your anemia, you should have more energy and start feeling like your old self again.
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
No specific preparation is necessary.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
LDH is most often measured to check for tissue damage. LDH is in many body tissues, especially the heart, liver, kidney, muscles, brain, blood cells, and lungs.
Other conditions for which the test may be done include:
Normal Results
Normal value range is 125 to 220 international units per liter (IU/L).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific results.
What Abnormal Results Mean
A higher-than-normal level may indicate:
- Blood flow deficiency (ischemia)
- Heart attack
- Hemolytic anemia
- Infectious mononucleosis
- Leukemia or lymphoma
- Liver disease (for example, hepatitis)
- Low blood pressure
- Muscle injury
- Muscle weakness and loss of muscle tissue (muscular dystrophy)
- New abnormal tissue formation (usually cancer)
- Pancreatitis
- Stroke
- Tissue death
If your LDH level is high, your provider may recommend an LDH isoenzymes test to determine the location of any tissue damage.
Risks
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
References
Panteghini M. Serum enzymes. In: Rifai N, Chiu RWK, Young I, Burnham CD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. St Louis, MO: Elsevier; 2023:chap 32.
Pincus MR, Carty RP. Clinical enzymology. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 21.
Version Info
Last reviewed on: 3/31/2024
Reviewed by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
