E03.2

HCC Category Mapping

What This Code Means

Low thyroid function caused by medications or other external substances that interfere with thyroid hormone production or function.

Coding Tips

• •Identify and document the specific medication or substance causing the hypothyroidism (e.g., amiodarone, lithium, iodine contrast)
• •Include the drug name in the medical record and consider using an additional code for the adverse effect if applicable

Clinical Significance

Hypothyroidism due to medicaments and other exogenous substances is an iatrogenic condition caused by medications or external agents that suppress thyroid function. Common causative agents include amiodarone, lithium, interferon-alpha, tyrosine kinase inhibitors, and immune checkpoint inhibitors. Recognition of the medication-induced etiology is critical because management may involve dose adjustment, drug discontinuation, or thyroid hormone replacement while continuing the necessary medication.

Documentation Requirements

• ✓Documentation must identify the specific causative medication or exogenous substance and establish the causal relationship to the hypothyroidism.
• ✓Thyroid function tests before and after medication initiation, the clinical decision regarding continuing or discontinuing the offending agent, and any thyroid replacement therapy should be documented.
• ✓An additional adverse effect code (T36-T65) should be assigned to identify the specific substance.

Commonly Confused Codes