What is the ICD-10 code for hypothyroidism?

The ICD-10-CM code for hypothyroidism is E03.9 when documented without further specification. More specific documentation changes the code — see the scenario table.

Yes — E03.9 is a billable ICD-10-CM code, but payers expect the most specific code the documentation supports.

ICD-10 Code for hypothyroidism

The ICD-10-CM code for hypothyroidism is E03.9 when documented without further specification. RxHCC Unspecified hypothyroidism is E03.9; autoimmune (Hashimoto's) and post-surgical causes have their own codes.

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Which Code Should You Use?

E03.9 ✓ Billable — Hypothyroidism, unspecified

Hypothyroidism documented without a specified cause.

E06.3 ✓ Billable — Autoimmune thyroiditis

Hashimoto's (autoimmune) thyroiditis documented.

E89.0 ✓ Billable — Postprocedural hypothyroidism

Postprocedural hypothyroidism (after thyroidectomy or radioablation).

E02 ✓ Billable — Subclinical iodine-deficiency hypothyroidism

Subclinical iodine-deficiency hypothyroidism.

What to Document

Cause when known (autoimmune, post-surgical, drug-induced E03.2).
Long-term levothyroxine therapy (no Z79 analog - the condition code suffices).
Pregnancy context (O99.28- applies as the first-listed code).

Also Known As

Official ICD-10-CM Alphabetic Index terms that point to E03.9:

Myxedema (adult) (idiocy) (infantile) (juvenile)
Hypothyroidism (acquired)
Hoffmann's syndrome
Insufficiency, insufficient › thyroid (gland) (acquired)
Cataract (cortical) (immature) (incipient) › myxedema
Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › in (due to) › hypothyroidism, acquired
Arthropathy › in (due to) › hypothyroidism
Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute) › in (due to) › hypothyroidism NEC

Coding Notes

"Hypothyroidism" alone indexes to E03.9. Myxedema coma is the higher-acuity E03.5.

Prevalence & Statistics

Nearly 5 out of 100 Americans ages 12 years and older have hypothyroidism, although most cases are mild or have few obvious symptoms. (NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases) - Hypothyroidism (Underactive Thyroid), 2021)