The difference of units between IU/mL and copies/mL

Many small partners see the biological field always appears IU / mL and copies/mL of these two units, always confused about the difference between the two, in fact, these two units in definition, application, and conversion, there are significant differences, listen to my detailed explanation below.

First, the definition of IU / mL and copies/mL

‘IU’ stands for International Unit, which is a unit of measurement used in pharmacology to express certain antibiotics, hormones, vitamins and antitoxins, and other biologically active substances. ‘mL’ stands for milliliter, a unit of volume. Therefore, IU/mL is used to describe the amount of IU per milliliter of liquid, i.e. the concentration of the substance.

 ‘Copy’ is the English word for copy, and in virus detection, one copy is usually regarded as one virus. Therefore, copy/mL is used to indicate the number of virus copies contained in each milliliter of liquid, which is also a way to indicate the concentration of the substance.

Application of IU/mL and copy/mL

IU/mL is widely used in the fields of medicine, biology, and pharmacy, especially in describing the concentration of antibiotics, hormones, and other biologically active substances. For example, in Hepatitis B virus DNA testing, IU/mL is a commonly used unit to assess the level of replication activity of the virus in the body.

Copies/mL are mainly used in the field of viral testing, especially when an accurate count of the number of viruses is required. In addition to Hepatitis B virus DNA testing, copy/mL is also widely used in the quantitative testing of other viruses.

Conversion relationship

The conversion relationship between IU/mL and copies/mL is not fixed but depends on the specific test methods and kits. Different hospitals or laboratories may use different reagents and testing methods, so even for the same substance, the conversion relationship between IU/mL and copies/mL may be different.

Specific conversion example: In Hepatitis B DNA testing, in general, 1 IU/mL of Hepatitis B DNA is approximately equal to 5 copies/mL, but this conversion relationship may vary slightly depending on the laboratory or test method. For example, the Roche COBAS AmpliPrep kit states that 1 IU = 5.82 copies.

It is important to note that when performing a viral test, it is important to focus on the specific assay and kit information. Different test methods and kits may have different sensitivity and accuracy, which may affect the reliability and accuracy of the test results.

In summary, there are significant differences between IU/mL and copies/mL in terms of definition, application, and conversion. When interpreting test results, it is necessary to correctly understand and differentiate the significance and conversion relationship between these two units, and pay attention to the specific test method and kit information.