2027 ICD-10-CM Diagnosis Code E21.5Disorder of parathyroid gland, unspecified
ICD-10-CM Codes›E00–E89›E20-E35›E21
- Billable — Valid for Submission
- Chronic Condition
E21.5 is a billable ICD-10-CM diagnosis code for disorder of parathyroid gland, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 643 through 645. Coders also document this condition as anemia of endocrine disorder. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified endocrine disorders.
E21.5 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 23 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 23, ESRD (V21) category 23, ESRD (V24) category 23, and RxHCC Part D (V08) category 43 for payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
E21.5 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Anemia of endocrine disorder
- Anemia of parathyroid dysfunction
- Disorder of parathyroid gland
- Polyneuropathy due to disorder of parathyroid gland
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to E21.5: its own notes plus those printed at E21, block E20-E35, and Chapter 4. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- 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.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name E21.5, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming E21.5: they are not reported together with it, unless the two conditions are unrelated.
- E83 Disorders of mineral metabolism
Code First 2
These codes say to code first a condition named in the note, and E21.5 is one of the conditions named.
Notes 1
These notes mention E21.5.
- Chapter 4 (E00-E89) Endocrine, nutritional and metabolic diseasesAll 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. names E16-E31, which includes this code
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
parathyroid (gland) E21.5
Disorder (of) See Also: Disease;
parathyroid (gland) E21.5
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
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.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert E21.5 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About E21.5Overview
What is the ICD-10 code for disorder of parathyroid gland, unspecified?
The ICD-10-CM code for disorder of parathyroid gland, unspecified is E21.5 (sometimes written as E215). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is E21.5 (Hyperparathyroidism and other disorders of parathyroid gland) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report disorder of parathyroid gland, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does E21.5 group to?
When disorder of parathyroid gland, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 644, 645, 643, with relative weights from 0.7461 to 1.6138 depending on complications. Higher weights mean higher Medicare reimbursement.
Can E21.5 be reported with a code from M83?
Not as a rule. The Excludes1 note at E21, which applies to E21.5, lists "adult osteomalacia (M83.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of E21.5?
Under the General Equivalence Mappings, disorder of parathyroid gland, unspecified converts to ICD-9-CM 252.9 (parathyroid disorder NOS). The mapping is a direct match.
Does E21.5 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. E21.5 mapped to HCC 23 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 23 (Other Significant Endocrine and Metabolic Disorders), ESRD (V21) category 23 (Other Significant Endocrine and Metabolic Disorders), ESRD (V24) category 23 (Other Significant Endocrine and Metabolic Disorders), and RxHCC Part D (V08) category 43 (Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders).
