What do International Classification of Diseases (ICD) codes describe?

International Classification of Diseases (ICD) codes are specifically designed to classify and code diagnoses, symptoms, and health-related conditions. They provide a standardized method for documenting diseases and medical conditions in both clinical settings and for insurance purposes. This coding system allows for uniformity in healthcare reporting and research, ensuring that all healthcare providers accurately describe the patient's current health issues.

In contrast, medical procedures performed are typically captured by a different coding system, known as Current Procedural Terminology (CPT) codes. Patient demographics, such as age and gender, are relevant for various aspects of healthcare but are not captured by ICD codes. Additionally, healthcare providers’ specialties are not classified through ICD codes; rather, they might relate to billing or organizational aspects of healthcare delivery. Thus, the role of ICD codes is to focus on the specific diseases or conditions that patients present with, making option C the correct choice.