Normally, one of the most frequent problems that translators have to deal with is the translation of abbreviations or acronyms. Note that an abbreviation is the formation of a word from the first letter of each of the words that are part of it. Acronyms, however, are abbreviations that are pronounced as a word (e.g. “sonar” or “NATO”).
In general terms, these are some of the most important guidelines for the translation of abbreviations (examples in this post are between Spanish and English, but apply to nearly all language pairs):
1. When it refers to a company or agency that may not be widely recognized (DEA, UBA, LAPD), translate the name and then place in parentheses: the acronym followed by “for its acronym in [language of origin]” or the abbreviation followed by an explanation in English.
For example: Buenos Aires University (UBA, for its acronym in Spanish) or Buenos Aires University (UBA, Universidad de Buenos Aires).
2. Abbreviations of world-renowned international organizations generally have their own translation in each language (WFP = PMA, NATO = OTAN). In this case, write the full name and abbreviation in brackets.
E.g. United Nations (UN)
3. Acronyms related to medicine (those that refer to diseases, compound names of body parts, etc.) also have a default translation: TC = CT (computed tomography), SIDA = AIDS (acquired immunodeficiency syndrome).
4. Abbreviations of job titles (CFO, CEO, CTO), names of countries (USA), political organizations (ETA, IRA, etc.). For these cases, some investigation is necessary, since some acronyms have a standardized translation (e.g., IRA is translated in Spanish as ERI, Ejército Revolucionario Irlandés) and others do not.
Other rules that are important to consider:
1) A lowercase “s” is added at the end to form the plural: “met the CEOs of 10 companies …”.
2) The letters do not have an accent in languages with accented letters.
3) Almost all the letters are capitalized (some exceptions are “laser” and “radar”).
(Versión en español: http://blog-de-traduccion.trustedtranslations.com/traduccion-de-siglas-2012-06-06.html)