E21.0
Primary hyperparathyroidism
E21.0 (also written E210) is a billable ICD-10-CM diagnosis code for primary hyperparathyroidism. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 6 codes in category E21 (Hyperparathyroidism and other disorders of parathyroid gland). The Alphabetic Index lists it under 11 entries. Its coding notes include 7 Excludes1 entries and 1 Excludes2 entry.
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
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, 2026Inclusion terms
Conditions classified to this code.
- Hyperplasia of parathyroid
- Osteitis fibrosa cystica generalisata [von Recklinghausen's disease of bone]
Notes
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. 11 entries
- Curvature, spine (acquired) (angular) (idiopathic) (incorrect) (postural), due to or associated with, osteitis, fibrosa cystica
- Disease, diseased, osteofibrocystic
- Enlargement, enlarged, parathyroid (gland)
- Hyperparathyroidism, primary
- Hyperplasia, hyperplastic, parathyroid (gland)
- Hypertrophy, hypertrophic, parathyroid (gland)
- Osteitis, fibrosa NEC, cystica (generalisata)
- Osteitis, fibrosa NEC, osteoplastica
- Osteitis, parathyroid
- Recklinghausen disease, bones
- Von Recklinghausen, disease (neurofibromatosis), bones