Is ICD-10-CM code E21 billable?

No, E21 (Hyperparathyroidism and other disorders of parathyroid gland) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code E21 belong to?

E21 belongs to Chapter 4 of the ICD-10-CM tabular list: E00–E89 (Endocrine, Nutritional and Metabolic Diseases).

E21Not billable, use a more specific code below

Hyperparathyroidism and other disorders of parathyroid gland

In Disorders of other endocrine glands (E20-E35), chapter 4: Endocrine, Nutritional and Metabolic Diseases

6 billable codes under E21: none are a CC or MCC; none map to an HCC.

Instructional notes

Excludes1: not coded here, use a different code

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

Excludes2: not included here, code separately if applicable

familial hypocalciuric hypercalcemia (E83.52)

Also applies, from Disorders of other endocrine glands (E20-E35)

These notes sit on E20-E35 and apply to every code under it, including E21.

Excludes1: not coded here, use a different code

galactorrhea (N64.3)
gynecomastia (N62)

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Covers diabetes mellitus coding, including type, insulin and drug use, pump malfunction and secondary diabetes, plus obesity and obesity class codes.

Diabetes mellitus (page 39)
Obesity (page 42)

Read Section I.C.4 (page 39)

All codes under E21

E21 can't be used on a claim. Pick a billable code below; grey headings group them.

E21 MS-DRGs

As the principal diagnosis, all 6 billable codes under E21 group to MS-DRG 643, 644, or 645 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

Other codes that refer to E21

Notes on these codes point to E21.

E83 Excludes1: parathyroid disorders (E20-E21)
M14.8 Code First: hyperparathyroidism (E21.-)

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Parathyroid Disorders

Most people have four pea-sized glands, called parathyroid glands, on the thyroid gland in the neck. Though their names are similar, the thyroid and parathyroid glands are completely different. The parathyroid glands make parathyroid hormone (PTH), which helps your body keep the right balance of calcium and phosphorous.

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.