Underdosing of antithyroid drugs, subsequent encounter

This code signifies that a patient is experiencing adverse effects or complications because they are not taking enough of their prescribed antithyroid medication. This underdosing is leading to a recurrence or worsening of hyperthyroid symptoms. It indicates a failure to achieve the desired therapeutic effect due to insufficient drug intake.

This code is appropriate for follow-up visits where a patient's hyperthyroidism is poorly controlled due to non-adherence or an insufficient dosage of antithyroid drugs. It should be used when the physician is managing the ongoing consequences of the underdosing, such as adjusting medication, monitoring thyroid function, or treating persistent hyperthyroid symptoms.

• Always assign an additional code for the specific manifestation of the hyperthyroidism (e.g., E05.90 for thyrotoxicosis, unspecified).
• Ensure documentation clearly states the underdosing is the cause of the current clinical presentation and that this is a subsequent encounter.
• Distinguish from initial encounters (A) or sequela (S) encounters; this code is specifically for ongoing management (D).