The E04.1 Diagnosis Code, as defined within the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM), is a billable code used to specify a diagnosis for medical reimbursement and statistical tracking. Specifically, E04.1 refers to a nontoxic single thyroid nodule, a condition characterized by a solitary, noncancerous growth on the thyroid gland that does not cause hyperthyroidism. This code is crucial for healthcare professionals and medical coders in accurately documenting and classifying this particular thyroid condition.
Effective from October 1, 2024, the 2025 edition of ICD-10-CM lists E04.1 as a valid and specific code. It’s important to note that while this is the American ICD-10-CM version, international versions of ICD-10 E04.1 might have slight variations. Therefore, when dealing with medical coding, especially in international contexts, always verify the specific coding guidelines applicable to the region.
The E04.1 code is applicable to several related terms, ensuring comprehensive coverage for this diagnosis. These applicable terms include:
- Colloid nodule (cystic) of the thyroid: This describes a common type of benign thyroid nodule filled with colloid, which can sometimes form cysts.
- Nontoxic uninodular goiter: This term highlights the non-cancerous nature of the single nodule and the absence of thyrotoxicosis (hyperthyroidism). “Uninodular” emphasizes that it is a single nodule, differentiating it from multinodular goiter.
- Thyroid (cystic) nodule NOS (Not Otherwise Specified): This broad term covers cystic thyroid nodules when further specification is not available in the medical record.
Understanding the synonyms for E04.1 can further clarify its meaning and aid in accurate code assignment. Common approximate synonyms include:
- Cyst of thyroid
- Dominant nodule of thyroid
- Dominant thyroid nodule
- Functioning thyroid nodule (in a nontoxic context)
- Non-toxic uninodular goiter
- Thyroid cyst
- Thyroid goiter, nontoxic, uninodular
- Thyroid nodule
- Thyroid nodule, functioning (nontoxic)
It’s also helpful to understand where E04.1 fits within the broader ICD-10-CM code structure. It falls under the category of E04 – Other nontoxic goiter, which sits within the larger chapter of Endocrine, Nutritional and Metabolic Diseases (E00-E89). Codes adjacent to E04.1 provide context and differentiation within thyroid disorders:
- E04.0 – Nontoxic diffuse goiter: Enlargement of the entire thyroid gland without toxicity.
- E04.2 – Nontoxic multinodular goiter: Presence of multiple nontoxic nodules in the thyroid.
- E05.1 – Thyrotoxicosis with toxic single thyroid nodule: In contrast to E04.1, this code describes a single thyroid nodule that is toxic, causing hyperthyroidism.
The history of the E04.1 code is straightforward; it was introduced as a new code in 2016 (effective October 1, 2015) with the initial non-draft ICD-10-CM release and has remained unchanged in subsequent yearly updates through 2025. This stability indicates the code’s established and consistent use in medical classification.
In conclusion, the E04.1 diagnosis code is a specific and billable ICD-10-CM code designating a nontoxic single thyroid nodule. Understanding its definition, applicable terms, synonyms, and context within related codes is essential for accurate medical coding, ensuring appropriate reimbursement and data collection for this common thyroid condition.
