Skip to main content
An official website of the United States government
Español
Government Funding Lapse
Because of a lapse in government funding, the information on this website may not be up to date, transactions submitted via the website may not be processed, and the agency may not be able to respond to inquiries until appropriations are enacted.

The NIH Clinical Center (the research hospital of NIH) is open. For more details about its operating status, please visit cc.nih.gov.

Updates regarding government operating status and resumption of normal operations can be found at opm.gov.

IU

A unit used to measure the activity of many vitamins, hormones, enzymes, and drugs. An IU is the amount of a substance that has a certain biological effect. For each substance there is an international agreement on the biological effect that is expected for 1 IU. Also called International Unit.
Search NCI's Dictionary of Cancer Terms