E03.3

HCC Category Mapping

What This Code Means

Low thyroid function that develops after a thyroid infection or inflammation has resolved, where the infection damages the thyroid's ability to produce hormones.

Coding Tips

• •Document the preceding infection or inflammatory condition (e.g., viral thyroiditis, bacterial infection) in the medical record
• •Verify the hypothyroidism persists after the acute infection phase to confirm postinfectious etiology

Clinical Significance

Postinfectious hypothyroidism develops as a sequela of thyroid gland infection or inflammation, most commonly following subacute thyroiditis (De Quervain thyroiditis) caused by viral infections. The thyroid gland is damaged by the infectious/inflammatory process, leading to permanent destruction of thyroid follicular cells and subsequent hypothyroidism. While many cases of subacute thyroiditis resolve with complete thyroid recovery, approximately 5-15% progress to permanent hypothyroidism.

Documentation Requirements

• ✓Documentation should establish the temporal relationship between a preceding infection or infectious thyroiditis and the subsequent development of hypothyroidism.
• ✓Prior episodes of thyroiditis, thyroid function test trajectory showing progression from thyrotoxicosis to hypothyroidism, and evidence of permanent thyroid damage should be documented.
• ✓Current thyroid replacement therapy and monitoring should be recorded.

Commonly Confused Codes