E21.0 Primary hyperparathyroidism

The ICD-10-CM code for Primary hyperparathyroidism is E21.0 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

4: Endocrine, nutritional and metabolic diseases (E00-E89)

Section

E20-E35: Disorders of other endocrine glands (E20-E35)

Category E21

7 codes (6 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to E21.0:

• Osteitis › parathyroid
• Hypertrophy, hypertrophic › parathyroid (gland)
• Hyperparathyroidism › primary
• Hyperplasia, hyperplastic › parathyroid (gland)
• Recklinghausen disease › bones
• Enlargement, enlarged › parathyroid (gland)
• Disease, diseased › osteofibrocystic
• Osteitis › fibrosa NEC › cystica (generalisata)

Inclusion Terms

• Hyperplasia of parathyroid
• Osteitis fibrosa cystica generalisata [von Recklinghausen's disease of bone]

U.S. Hospital Utilization

• An estimated 30,165 U.S. inpatient stays in 2023 included E21.0 among the documented diagnoses.
• 2,605 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Diabetes mellitus (TOC entry)

a. Diabetes mellitus ................................................................................................................... 39

Obesity (TOC entry)

b. Obesity .................................................................................................................................. 42

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)