What's the plural form of hyperthyroxinemia? Here's the word you're looking for.
Answer
The noun hyperthyroxinemia can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be hyperthyroxinemia.
However, in more specific contexts, the plural form can also be hyperthyroxinemias e.g. in reference to various types of hyperthyroxinemias
or a collection of hyperthyroxinemias.