anemia: Style Guide Spelling Decisions (AP, Chicago, MLA, APA)

How major style guides rule on "anemia"

American style drops the 'a' from 'ae' digraphs in medical terms; British retains them: anemia/anaemia, leukemia/leukaemia, pediatric/paediatric.

The disagreement on "anemia" is an example of medical-spelling differences between American and British style, the category of style-guide differences that most often confuses copy editors and creates inconsistency across long documents. Below is a guide-by-guide breakdown, drawn directly from the published editions cited.

What the divergence actually means

Unlike many compound-modernization decisions where style guides eventually converge, "anemia" continues to show genuine divergence between major guides. The AP Stylebook treats this as a settled call; Chicago Manual leaves more flexibility; and Merriam-Webster, as a descriptive dictionary, records both forms. Source: Chicago Manual of Style, 17th Edition

The APA Publication Manual aligns with AP and Chicago on "anemia", though APA generally addresses spelling questions only when they intersect with statistical reporting or technical psychology vocabulary. Where the manual is silent, APA defers to Merriam-Webster as its standard reference. Source: APA Publication Manual, 7th Edition

Merriam-Webster lists "anemia (UK: anaemia)", which serves as the lexicographic baseline for U.S. style decisions. Because Merriam-Webster's entries reflect aggregated published usage rather than editorial preference, when a guide says "follow Merriam-Webster", as APA does, that effectively delegates the call to whichever spelling has dominated the published corpus. Source: Merriam-Webster Dictionary

Garner's Modern English Usage classifies the "anemia" / "anaemia" pair on its Language-Change Index, a five-stage scale measuring whether a once-disputed form has been accepted into Standard English. For medical-spelling differences between American and British style, Garner's typically rates the dominant form at Stage 4 ("ubiquitous but objected to by traditionalists") or Stage 5 ("fully accepted"). Source: Garner's Modern English Usage, 5th Edition

Practical guidance for editors

For working writers, the practical rule is straightforward: in journalism, follow AP; in academic writing in the humanities, follow MLA or Chicago; in social-science publishing, follow APA; in book publishing, follow Chicago. When no house style applies, Merriam-Webster's main entry is the safest default. The differences across these guides on "anemia" reflect not disagreement about correctness but different audiences and editorial pressures.

Editorial context

In international medical publishing, the spelling anaemia persists despite American dominance in global style, particularly in organizations prioritizing British English conventions like the World Health Organization, whose reports consistently employ it to align with Commonwealth standards. For instance, a WHO fact sheet might state: Anaemia affects one in three people worldwide, predominantly women and children. This register split endures because medical terminology often draws from classical Greek and Latin roots, where the æ digraph (ænemia) was historically retained in British lexicography, as seen in the Oxford English Dictionary's preference for anaemia as the headword form. Google Books N-grams for British English show anaemia maintaining a lead through the 20th century, only marginally ceding ground post-2000 amid Americanization, underscoring how formal UK and global health contexts resist US simplification for precision in etymological fidelity and audience targeting.

Cross-references

For the dictionary entry, frequency data, and pronunciation of anemia, see the main word page. For other style-guide spelling decisions in this category, browse all style-guide spelling rulings.