Underdosing of drug/meds/biol subst, init

This code signifies that a patient has received less than the prescribed or therapeutically required amount of a medication, biological substance, or other drug, leading to a suboptimal clinical effect or failure to achieve the intended treatment outcome. It indicates that the underdosing is the primary reason for the current encounter and is not a subsequent event.

Use this code when a patient presents with symptoms or conditions due to insufficient administration of a drug, such as a missed dose of insulin leading to hyperglycemia, or inadequate antibiotic dosage resulting in persistent infection. This applies to situations where the underdosing is the focus of the initial evaluation and treatment.

• Always assign an additional code for the specific drug or substance underdosed (e.g., T38.3X6- for insulin).
• Also code the specific condition or symptom resulting from the underdosing (e.g., E11.65 for hyperglycemia due to insulin underdosing).
• Ensure the "A" seventh character is used only for the initial encounter where the underdosing is first identified and treated.