Underdosing of antithyroid drugs, initial encounter

This code signifies that a patient has not received enough of their prescribed antithyroid medication, leading to an inadequate therapeutic effect. This underdosing can result in uncontrolled hyperthyroidism or a worsening of thyroid-related symptoms.

Apply this code when documentation indicates a patient is experiencing adverse effects or a lack of improvement due to insufficient antithyroid drug intake. This includes situations where the patient intentionally or unintentionally takes less than the prescribed dose, or if the prescribed dose itself was inadequate.

• Always sequence this code after the primary diagnosis indicating the condition being treated (e.g., hyperthyroidism).
• Ensure documentation clearly specifies "underdosing" and identifies the drug class as antithyroid.
• The "A" in the seventh character indicates an initial encounter for this specific underdosing event.