E02 Subclinical iodine-deficiency hypothyroidism

ICD-10-CM Code E02: Subclinical iodine-deficiency hypothyroidism

ICD-10-CM code E02 represents subclinical iodine-deficiency hypothyroidism, a diagnosis or health-status concept active in the 2026 terminology version. It falls under the E00-E07 parent category for thyroid gland disorders. The code identifies a subclinical hypothyroid pattern linked to insufficient iodine intake, characterized by elevated thyroid-stimulating hormone and normal free thyroxine levels. 1 2 4

Plain-language overview

Code E02 identifies a condition where the thyroid gland produces insufficient hormone due to inadequate dietary iodine, presenting with elevated thyroid-stimulating hormone alongside normal free thyroxine levels. 4

Clinical features indicative of subclinical hypothyroidism include elevated levels of thyroid-stimulating hormone and normal free thyroxine, though some individuals may present with a low thyroxine level instead. 2

What this code represents

E02 is the billable diagnosis code for subclinical iodine-deficiency hypothyroidism, restricted specifically to the iodine-deficiency subclinical pattern rather than a broader range of acquired hypothyroidism cases. 4

The terminology record classifies E02 with the semantic type of Disease or Syndrome, placing it under the parent concept E00-E07 for disorders of the thyroid gland. 1

Coding details

The E03 category for other hypothyroidism carries a Type 1 Excludes note that explicitly lists subclinical iodine-deficiency hypothyroidism, meaning E02 must be used instead of E03 for this specific condition. 4

E02 serves as the specific code when clinical documentation ties the subclinical hypothyroid pattern directly to iodine deficiency, distinguishing it from other iodine-deficiency-related thyroid disorders in category E01. 4 5

Documentation considerations

Documentation elements for E02 include laboratory parameters showing elevated thyroid-stimulating hormone with normal free thyroxine, alongside a clinical note linking the subclinical pattern to inadequate dietary iodine. 2 4

Coverage and utilization context

E02 can support a lab-only encounter when the ordering diagnosis is established subclinical iodine-deficiency hypothyroidism, and may be assigned as the primary diagnosis for an office visit focused on thyroid monitoring. 4

What the sources add

While the clinical reference details cardiovascular risk evaluations and levothyroxine treatment parameters for subclinical hypothyroidism, the coding sources establish that E02 strictly requires documentation of an iodine-deficiency etiology. 2 4

Sources

1. ICD-10-CM E02 terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. Bookshelf — ncbi.nlm.nih.gov; accessed 2026-07-27.
3. ICD-10 Version:2014 — icd.who.int; accessed 2026-07-27.
4. ICD-10 Code E02: Subclinical iodine-deficiency hypothyroidism — pabau.com; accessed 2026-07-27.
5. E | ICD-10-CM 2024 — unboundmedicine.com; accessed 2026-07-27.