What does the suffix "in" commonly indicate in medical terminology?

The suffix "in" in medical terminology often signifies a type of protein or a substance that has a protein-like characteristic. This can be seen in various terms such as "albumin," which is a protein found in blood, or "insulin," which plays a crucial role in glucose metabolism in the body. The use of "in" as a suffix helps to categorize and identify substances that are vital for biological processes, particularly those related to nutrition and metabolism.

The other options represent categories of nutrients as well, but they do not utilize the suffix "in" in their standard nomenclature. For instance, carbohydrates are not typically described with this suffix, nor are fats or minerals. Understanding these suffixes can enhance your grasp of medical terminology, especially in fields related to nutrition and physiology.