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Normal LDH level in the blood

Blood test
Normal LDH level in the blood
Last update: 24/11/2020

What is the normal level of LDH in the blood?

Adults 130 - 240 UI/l
Children from 12 to 18 years old: 100 - 290 UI/l
Children from 2 to 12 years old: 120 - 345 UI/l
Children up to 2 years old: 155 - 395 UI/l
Babies from 1 month to 1 year old: 170 - 450 UI/l
Newborns (1 to 30 days old): 125 - 765 UI/l

In the International System of Units (SI), LDH in the blood is measured in µkat/L. The normal LDH level in the blood in the SI is:

Adults 2.17 - 4 µkat/l
Children from 12 to 18 years old: 1.67 - 4.84 µkat/l
Children from 2 to 12 years old: 2 - 5.76 µkat/l
Children up to 2 years old: 2.58 - 6.59 µkat/l
Babies from 1 month to 1 year old: 2.83 - 7.51 µkat/l
Newborns (1 to 30 days old): 2.08 - 12.77 µkat/l

Why normal levels can differ across different labs?

Each laboratory must establish its own normal ranges for LDH in the blood. These ranges depend on the makeup of the local population, the technologies used and the accuracy of the measurement. There may be also slight differences in the normal levels, according to age, gender, race or ethnic origin, geographic region, diet, type of sample and other relevant status.

Your doctor will study the results along with your medical record, screenings, physical condition, symptoms and any other relevant information about your situation.

The normal ranges of LDH in the blood may be very different from lab to lab depending on the technique and the temperature at which it is measured. One of the most used methods follows the IFCC standard at 37ºC and it is the one explained in this guide. In case your test is performed at a different temperature (for example 30ºC) or with a different technique, the normal range may differ. For that reason, it is very important to check the normal range that appears in your report.

Besides, LDH may be measured in different fluids such as urine or cerebral spinal fluid (CSF). In the CSF, the normal range is approximately a 10% of the amount in the blood. An elevation of LDH in CSF is a sign of bacterial meningitis.

What is the role of LDH in the body?

LDH (lactate dehydrogenase), also called lactic acid dehydrogenase or LD, is a hydrogen transfer enzyme, from the oxidoreductase family, that catalyzes the reversible conversion of lactic acid to pyruvic acid. For this reason, it plays an important role in the regulation of the body's energy.

LDH is found in many body tissues of the body particularly heart, liver, skeletal muscle, kidney and RBCs (Red Blood Cells). It is also present in other organs such as the kidneys, pancreas, spleen, brain, and lungs.

LDH is found in the form of isoenzymes based on their electrophoretic mobility. There are five main isoenzymes being each one primarily from a different organ:

  • LDH1 (17 to 27% of total LDH): It is primarily from the heart and erythrocytes (RBC).
  • LDH2 (23 to 38% of total LDH): It comes mostly from the reticuloendothelial system.
  • LDH3 (18 to 28% of total LDH: It is from the lungs.
  • LDH4 (5 to 15% of total LDH): It comes from the placenta, kidneys, and pancreas.
  • LDH5 (5 to 15% of total LDH): It is largely from the liver and striated muscle.

In a normal situation, LDH2 is the isoenzyme that contributes more to the total LDH.

What is the LDH blood test used for?

A LDH blood test is usually used as an indicator of tissue damage. When tissues are damaged, they release LDH isoenzymes into the bloodstream depending on the location and severity of the injury.

Therefore, an increase of LDH in the blood is a pathological condition that occurs when tissues are damaged. A serum LDH increase may be related to myocardial infarction, liver diseases, pernicious anemia, megaloblastic anemia, renal diseases, malignant diseases, and progressive muscular dystrophy.

A total LDH increase is not specific for any disease and it is necessary to know the isoenzyme causing the increase to give a more appropriate diagnosis.

For example, myocardial infarctions and hemolytic anemias tend to cause elevations in LDH1 and LDH2, LDH3 is elevated in pulmonary infarction while LDH5 is usually elevated due to liver disorders. Malignant tumors, in general, cause increases in LDH2, LDH3 and LDH4.

LDH levels below the normal range are rare and give usually no medical information. However, there are some genetic disorders related to a low LDH level in the blood. A decrease in the LDH level during a cancer treatment is usually a positive sign.

Where can I find more information about LDH level in the blood?

You can visit our pages about:

Which values are considered a normal LDH level in the blood?

The following values are considered to be normal values:

IMPORTANT: These levels are expressed in UI/l. They are an example of a healthy man of about 45 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

Lactate dehydrogenase (LDH)
130 UI/l132 UI/l134 UI/l136 UI/l138 UI/l140 UI/l142 UI/l144 UI/l
146 UI/l148 UI/l150 UI/l152 UI/l154 UI/l156 UI/l158 UI/l160 UI/l
162 UI/l164 UI/l166 UI/l168 UI/l170 UI/l172 UI/l174 UI/l176 UI/l
178 UI/l180 UI/l182 UI/l184 UI/l186 UI/l188 UI/l190 UI/l192 UI/l
194 UI/l196 UI/l198 UI/l200 UI/l202 UI/l204 UI/l206 UI/l208 UI/l
210 UI/l212 UI/l214 UI/l216 UI/l218 UI/l220 UI/l222 UI/l224 UI/l
226 UI/l228 UI/l230 UI/l232 UI/l234 UI/l236 UI/l238 UI/l240 UI/l
Medically reviewed by our Medical staff on 24/11/2020


  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 538.
  • Tietz. Fundamentals of Clinical Chemistry. Carl A. Burtis, Edward R. Ashwood, David E. Bruns, Barbara G. Sawyer. WB Saunders Company, 2008. Pag 321. ISBN: 978-0-7216-3865-2.
  • Laboratory tests and diagnostic procedures with nursing diagnoses (8th ed), Jane Vincent Corbett, Angela Denise Banks, ISBN: 978-0-13-237332-6, Pag. 285.

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