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ICD-10-CM 2027 diagnosis code

E21Hyperparathyroidism and other disorders of parathyroid gland

Not billable — use a more specific code

E21 is a header code, so it can't be reported by itself. Choose one of the 6 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About E21

E21 is the ICD-10-CM diagnosis code for hyperparathyroidism and other disorders of parathyroid gland. It belongs to block E20-E35 (disorders of other endocrine glands) and chapter 4 (endocrine, nutritional and metabolic diseases). It is a header code, so it can't be reported by itself; one of its 6 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: E21.0 (hyperparathyroidism), E21.1 (classified), E21.2 (hyperparathyroidism), E21.3 (unspecified), E21.4 (gland) and E21.5 (unspecified).

Don't report E21 together with the conditions in its Excludes1 note: adult osteomalacia (M83.-), ectopic hyperparathyroidism (E34.2), hungry bone syndrome (E83.81) and infantile and juvenile osteomalacia (E55.0).

The conditions in its Excludes2 note aren't part of E21, but may be coded alongside it if the patient has both: familial hypocalciuric hypercalcemia (E83.52).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under E21

Coding notes

Excludes1Not coded here — never report together with this code
  • adult osteomalacia (M83.-)
  • ectopic hyperparathyroidism (E34.2)
  • hungry bone syndrome (E83.81)
  • infantile and juvenile osteomalacia (E55.0)
Excludes2Not included here — may be reported together if both conditions exist
  • familial hypocalciuric hypercalcemia (E83.52)

Notes that apply from higher levels

Instructions written at a parent level also apply to E21.

Broader instructions also apply from E20-E35 Disorders of other endocrine glands and Chapter 4: Endocrine, nutritional and metabolic diseases.

Codes whose notes reference E21

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about E21

Is E21 billable?

No. E21 is a header code. Report one of its more specific subcodes instead.