Abbreviations

Punctuation

Do not punctuate abbreviations with periods, except with persons’ initials and the abbreviation for number.

Nonscientific abbreviations

Avoid general nonscientific abbreviations (see examples below) in running text; such abbreviations are acceptable in parenthetical phrases, in figures (but not figure legends), and in tables (but not table footnotes).

When specifying locations, do not abbreviate country names.

When abbreviating names of US states and Canadian provinces, use the 2-letter postal abbreviations.

In mailing addresses (eg, the corresponding author’s contact information paragraph), abbreviate street names and other mailing directions wherever possible. But do not abbreviate parts of institutional or department names.

Units of measurement

Abbreviate units of measurement (including base pair and kilobase) without expansion when they follow a numeric quantity, using abbreviations on the list below. For abbreviations not on the list, follow the AMA Manual of Style, 10th ed., section 14.12. But when a unit is used in a general fashion (unconnected with a numeric quantity), spell it out.

Scientific abbreviations

Choice of abbreviation

Any scientific abbreviation representing a noun is acceptable, as long as each abbreviation is used consistently.

Nonnoun abbreviations

In running text, avoid using abbreviations that represent nonnouns, including certain clinical abbreviations.

Such abbreviations may be used in figures and tables, as long as they are explained at the first occurrence.

Article titles

Abbreviations are generally allowed in titles. If an abbreviation is used in a title, it must be expanded (spelled out) in the abstract.

General rule for abstracts and main text

Expand all scientific abbreviations (a) on first use in the abstract and (b) on first use in the main text, with 3 exceptions:

1. If the abbreviation is on the list of exceptions, expansion is never required.
2. If an abbreviation is first used in a section heading, it need not be expanded in the heading, as long as it is expanded at first use in the text of that section.
3. Expansion of the names of genes, restriction enzymes, cell lines, and mouse strains is not required.

At each first instance, expand the abbreviation in running text and include the abbreviation afterward in parentheses. But abbreviations of certain long chemical names should be defined by putting the expansion in parentheses after the abbreviation; in order to preserve scientific meaning, be sure to retain any parentheses within the expansion when you put the expansion inside parentheses.

General rule for figures and tables

In figure legends and table footnotes, expand abbreviations only if they have not been expanded in the main text before that figure’s or table’s first callout. Similarly, if an abbreviation is first expanded in a figure or table, it need not be expanded in the main text or anywhere else.

Plural abbreviations

Make abbreviations plural by adding an “s” to the end, including abbreviations in which the last character does not represent the plural term.

Abbreviations that never need expansion

Examples of chemical compound abbreviations that should be expanded in parentheses

The above list is not exhaustive. Remember not to alter parentheses within these expansions, even if the entire expansion is within parentheses.

Abbreviations for units of measurement

* Use these abbreviations only in tables and ratios (eg, 250 mm/h).