AMA Manual of Style - Stacy L. Christiansen, Cheryl Iverson 2020

Agencies, Organizations, Foundations, Funding Bodies, and Others
Abbreviations

Many organizations (eg, academies, associations, government agencies, research institutes) are known by abbreviations or acronyms rather than by their full names. Some of these organizations have identical abbreviations (eg, AHA for both American Heart Association and American Hospital Association). Therefore, to avoid confusion, the names of all organizations should be expanded at first mention in the text and other major elements of the manuscript, with the abbreviation following immediately in parentheses, in accordance with the guidelines offered in 13.11, Clinical, Technical, and Other Common Terms.

The article the is often used with abbreviated forms of agencies and organizations (eg, the UN, the AMA, the FDA); however, an article is not necessary with forms pronounced as words (eg, NASA [nas-ah], OSHA [oh-shuh], WAME [wa-mee]).