Adverse effect of antithyroid drugs, subsequent encounter

This code signifies a harmful or undesirable reaction experienced by a patient due to the therapeutic use of antithyroid medications, such as methimazole or propylthiouracil. The "subsequent encounter" indicates that the patient is receiving follow-up care for the adverse effect after the initial treatment has been provided.

Apply this code when a patient presents for ongoing management, monitoring, or treatment of an adverse effect caused by antithyroid drugs. This includes scenarios where the patient is being evaluated for the effectiveness of interventions to mitigate the adverse reaction, or for long-term complications stemming from the drug.

• Always sequence this code after the code identifying the specific adverse effect (e.g., agranulocytosis, liver failure).
• Ensure documentation clearly states the antithyroid drug as the cause of the adverse effect and that this is not the initial presentation.
• Distinguish from poisoning (T49.4X-) or underdosing (T38.2X6-) which have different code assignments.