Alphabetic Index FY2027

E21

Hyperparathyroidism and other disorders of parathyroid gland

FY2027Chapter 4: Endocrine, nutritional and metabolic diseases/E20–E35 Disorders of other endocrine glands

Non-billable headerNot valid on its own. Use one of the more specific codes under it.

E21 is a non-billable ICD-10-CM code category for hyperparathyroidism and other disorders of parathyroid gland. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are E21.0 Primary hyperparathyroidism; E21.1 Secondary hyperparathyroidism, not elsewhere classified; E21.2 Other hyperparathyroidism; E21.3 Hyperparathyroidism, unspecified and 2 more. Its coding notes include 7 Excludes1 entries and 1 Excludes2 entry.

Excludes1

Not coded here. The listed conditions generally should not be reported together.

This code
  • adult osteomalacia (M83.-)
  • ectopic hyperparathyroidism (E34.2)
  • hungry bone syndrome (E83.81)
  • infantile and juvenile osteomalacia (E55.0)
Also from chapter/block level (3 notes)
Inherited from E20–E35 Disorders of other endocrine glands
Inherited from Chapter 4 Endocrine, nutritional and metabolic diseases
  • transitory endocrine and metabolic disorders specific to newborn (P70-P74)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

This code
  • familial hypocalciuric hypercalcemia (E83.52)

Notes

Also from chapter/block level (1 note)
Inherited from Chapter 4 Endocrine, nutritional and metabolic diseases
  • 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.

More specific codes under E21 6