Which code represents a routine medical check-up?

The correct choice for representing a routine medical check-up is CPT code 99396. This code is specifically designated for an "annual preventive medicine visit" for an established patient aged 65 years or older, which aligns with the concept of routine check-ups aimed at preventive health care measures.

In the context of preventive visits, CPT codes in the range starting with 99381 to 99397 are used for various age groups and types of preventive medicine visits. They often cover comprehensive evaluations that assess overall health, screen for potential health issues, and provide counseling on lifestyle modifications.

Other codes provided are linked to different types of services. For instance, CPT code 99213 is used for an office or other outpatient visit for an established patient, which typically encompasses a problem-focused encounter rather than a comprehensive routine check-up. Similarly, CPT code 99203 is for a new patient visit, and CPT code 99406 pertains to smoking and tobacco use cessation counseling, neither of which specifically describes a routine check-up.

Thus, CPT code 99396 is the most appropriate choice for denoting a routine medical check-up as it adheres to the preventive nature of such appointments, focusing on assessing and promoting general well-being.