E21.1 – Secondary hyperparathyroidism, not elsewhere classified

ICD-10-CM 2027 diagnosis code · Disorders of other endocrine glands

Billable code

ICD-10-CM code E21.1

Code: E21.1 (claims format: E211)
Description: Secondary hyperparathyroidism, not elsewhere classified
Billable: Yes – valid for HIPAA-covered transactions
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 4. Endocrine, nutritional and metabolic diseases (E00-E89)
Block: E20-E35 Disorders of other endocrine glands
Parent codes: E21

Notes for E21.1

Excludes1 (not coded here):

secondary hyperparathyroidism of renal origin (N25.81)

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

E21 – Hyperparathyroidism and other disorders of parathyroid gland

Excludes1 (not coded here):

adult osteomalacia (M83.-)
ectopic hyperparathyroidism (E34.2)
hungry bone syndrome (E83.81)
infantile and juvenile osteomalacia (E55.0)

Excludes2 (not included here):

familial hypocalciuric hypercalcemia (E83.52)

Block E20-E35

Excludes1 (not coded here):

galactorrhea (N64.3)
gynecomastia (N62)

Index terms for E21.1

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in E21

E21.0 – Primary hyperparathyroidismBillable
E21.2 – Other hyperparathyroidismBillable
E21.3 – Hyperparathyroidism, unspecifiedBillable
E21.4 – Other specified disorders of parathyroid glandBillable
E21.5 – Disorder of parathyroid gland, unspecifiedBillable

Frequently asked questions

What is ICD-10 code E21.1?

E21.1 is the ICD-10-CM code for secondary hyperparathyroidism, not elsewhere classified, in the block E20-E35 (Disorders of other endocrine glands).

Is E21.1 a billable code?

Yes. E21.1 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does E21.1 belong to?

It belongs to category E21 – Hyperparathyroidism and other disorders of parathyroid gland.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.