E05.21
Thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis or storm
E05.21 (also written E0521) is a billable ICD-10-CM diagnosis code for thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis or storm. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 14 codes in category E05 (Thyrotoxicosis [hyperthyroidism]). The Alphabetic Index lists it under 14 entries. Its coding notes include 3 Excludes1 entries.
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Home Health Primary
Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Endocrine clinical group.
Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026Hospital MCC
Counts as a major complication or comorbidity (MCC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 59 codes in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.
Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix CNotes
Also from chapter/block level (1 note)
- All neoplasms, whether functionally active or not, are classified in Chapter 2. Appropriate codes in this chapter (i.e. E05.8, E07.0, E16-E31, E34.-) may be used as additional codes to indicate either functional activity by neoplasms and ectopic endocrine tissue or hyperfunction and hypofunction of endocrine glands associated with neoplasms and other conditions classified elsewhere.
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 14 entries
- Goiter (plunging) (substernal), multinodular (cystic) (nontoxic), toxic or with hyperthyroidism, with thyroid storm
- Goiter (plunging) (substernal), nodular (nontoxic) (due to), toxic, with thyroid storm
- Goiter (plunging) (substernal), nodular (nontoxic) (due to), with, hyperthyroidism, with thyroid storm
- Goiter (plunging) (substernal), nodular (nontoxic) (due to), with, thyrotoxicosis, with thyroid storm
- Hyperthyroidism (latent) (pre-adult) (recurrent), with, goiter (diffuse), nodular (multinodular), with thyroid storm
- Nodule (s), nodular, thyroid (cold) (gland) (nontoxic), toxic or with hyperthyroidism, with thyroid storm
- Nodule (s), nodular, thyroid (cold) (gland) (nontoxic), with thyrotoxicosis, with thyroid storm
- Plummer's disease, with thyroid storm
- Struma, nodosa (simplex), toxic or with hyperthyroidism, multinodular, with thyroid storm
- Struma, nodosa (simplex), toxic or with hyperthyroidism, with thyroid storm
- Struma, nodosa (simplex), toxicosa, multinodular, with thyroid storm
- Struma, nodosa (simplex), toxicosa, with thyroid storm