2027 ICD-10-CM Diagnosis Code E20.812Autoimmune hypoparathyroidism

ICD-10-CM Codes›E00–E89›E20-E35›E20

ICD-10-CM E20.812
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

E20.812 is a billable ICD-10-CM diagnosis code for autoimmune hypoparathyroidism. 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, 791, 793. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified endocrine disorders.

E20.812 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

ICD-10-CM Code
E20.812
Billable Status
Yes — Valid for Submission
Code Describes
Autoimmune hypoparathyroidism
Short Description
Autoimmune hypoparathyroidism
Same as the full description in the CMS dataset.
Parent Code
E20.81
Hypoparathyroidism due to impaired parathyroid hormone secretion

Code Classification

ChapterE00–E89Endocrine, nutritional and metabolic diseases
SectionE20-E35Disorders of other endocrine glands
CategoryE20Hypoparathyroidism
This CodeE20.812Autoimmune hypoparathyroidism

Medicare Risk Adjustment (HCC)Billing

E20.812 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.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 23
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 23 · ESRD (V21): HCC 23 · ESRD (V24): HCC 23
ESRD V21 weights: 0.013 dialysis, 0.234–0.359 functioning graft · ESRD V24 weights: 0.036 dialysis, 0.217–0.390 functioning graft
Part D (RxHCC)
RxHCC 43 — Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders
also risk-adjusts in the Part D prescription drug model (V08)

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.

  • Autoimmune hypoparathyroidism

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to E20.812: its own notes plus those printed at E20, 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.

From E20 Hypoparathyroidism applies to 9 codes
  • Di George's syndrome (D82.1)
  • postprocedural hypoparathyroidism (E89.2)
  • tetany NOS (R29.0)
  • transitory neonatal hypoparathyroidism (P71.4)
From Block E20-E35 Disorders of other endocrine glands applies to 99 codes
From Chapter 4 (E00-E89) Endocrine, nutritional and metabolic diseases applies to 973 codes
  • transitory endocrine and metabolic disorders specific to newborn (P70-P74)

Code First

The underlying condition named in the note is sequenced before this code.

  • if applicable, underlying condition such as:
  • autoimmune polyglandular failure (E31.0)
  • Schmidt's syndrome (E31.0)

Notes

General instructions on how these codes are used.

From Chapter 4 (E00-E89) Endocrine, nutritional and metabolic diseases applies to 973 codes
  • 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 E20.812, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming E20.812: they are not reported together with it, unless the two conditions are unrelated.

  • E83.5 Disorders of calcium metabolism
    autoimmune hypoparathyroidism (E20.812)
  • E83 Disorders of mineral metabolism
    parathyroid disorders (E20-E21) names E20-E21, which includes this code

Code First 3

These codes say to code first a condition named in the note, and E20.812 is one of the conditions named.

  • G73.7 Myopathy in diseases classified elsewhere
    hypoparathyroidism (E20.-) names E20.-, which includes this code
  • H28 Cataract in diseases classified elsewhere
    hypoparathyroidism (E20.-) names E20.-, which includes this code
  • G63 Polyneuropathy in diseases classified elsewhere
    endocrine disease, except diabetes (E00-E07, E15-E16, E20-E34) names E20-E34, which includes this code

Notes 1

These notes mention E20.812.

  • Chapter 4 (E00-E89) 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. names E16-E31, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR END015
Other specified and unspecified endocrine disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Hypoparathyroidism

    a condition caused by a deficiency of parathyroid hormone (or pth). it is characterized by hypocalcemia and hyperphosphatemia. hypocalcemia leads to tetany. the acquired form is due to removal or injuries to the parathyroid glands. the congenital form is due to mutations of genes, such as tbx1; (see digeorge syndrome); casr encoding calcium-sensing receptor; or pth encoding parathyroid hormone.

Patient EducationClinical

Autoimmune Diseases

Your immune system protects you from disease and infection by attacking germs that get into your body, such as viruses and bacteria. Your immune system can tell that the germs aren't part of you, so it destroys them. If you have an autoimmune disease, your immune system attacks the healthy cells of your organs and tissues by mistake.

The full article covers:

  • What are autoimmune diseases?
  • What causes autoimmune diseases?
  • Who is at risk for autoimmune diseases?
  • What are the symptoms of autoimmune diseases?
  • How are autoimmune diseases diagnosed?
  • What are the treatments for autoimmune diseases?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement E20.812 replaces the following previously assigned code(s):

  • E20.8 - Other hypoparathyroidism
FY 2024AddedAdded to the ICD-10-CM code setEffective October 1, 2023.
FY 2025–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About E20.812Overview

What is the ICD-10 code for autoimmune hypoparathyroidism?

The ICD-10-CM code for autoimmune hypoparathyroidism is E20.812 (sometimes written as E20812). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is E20.812 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report autoimmune hypoparathyroidism on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does E20.812 group to?

When autoimmune hypoparathyroidism is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 644, 645, 643, with relative weights from 0.7461 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.

Can E20.812 be reported with D82.1?

Not as a rule. The Excludes1 note at E20, which applies to E20.812, lists "Di George's syndrome (D82.1)". 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 coded first with E20.812?

The Code First note reads: , if applicable, underlying condition such as: autoimmune polyglandular failure (E31.0); Schmidt's syndrome (E31.0). When one of these applies, it is sequenced before E20.812.

Does E20.812 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. E20.812 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).