2026 ICD-10-CM Diagnosis Code E26.01Conn's syndrome

ICD-10-CM Codes›E00–E89›E20-E35›E26

ICD-10-CM E26.01
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

E26.01 is a billable ICD-10-CM diagnosis code for Conn's syndrome. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 643 through 645. Coders also document this condition as adrenal adenoma. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified endocrine disorders.

Code Identity

ICD-10-CM Code
E26.01
Billable Status
Yes — Valid for Submission
Code Describes
Conn's syndrome
Short Description
Conn's syndrome
Same as the full description in the CMS dataset.
Parent Code
E26.0
Primary hyperaldosteronism

Code Classification

ChapterE00–E89Endocrine, nutritional and metabolic diseases
SectionE20-E35Disorders of other endocrine glands
CategoryE26Hyperaldosteronism
This CodeE26.01Conn's syndrome

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adrenal adenoma
  • Adrenal cortical adenoma
  • Aldosterone-producing adenoma
  • Benign neoplasm of adrenal cortex
  • Hyperaldosteronism due to neoplasm of the adrenal cortex
  • Primary hyperaldosteronism due to adrenal adenoma

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Code Also

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Conn's syndrome
    • Syndrome
      • Conn's

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

Patient EducationClinical

Adrenal Gland Disorders

Your adrenal glands are two small organs that sit on top of each kidney. The adrenal glands make different types of hormones you need to stay alive and healthy. Hormones are chemicals that travel in your bloodstream and control how different parts of your body work.

The full article covers:

  • What are adrenal glands?
  • What are adrenal gland disorders?
  • What causes adrenal gland disorders?
  • How are adrenal gland disorders diagnosed?
  • What are the treatments for adrenal gland disorders?

Read the full article at MedlinePlus

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

Convert E26.01 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
255.12 Conn's syndrome
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About E26.01Overview

Is E26.01 (Primary hyperaldosteronism) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report Conn's syndrome on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does E26.01 group to?

When Conn's syndrome is the principal diagnosis on an inpatient stay, it groups to MS-DRG 643, 644, 645, with relative weights from 0.7683 to 1.6461 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of E26.01?

Under the General Equivalence Mappings, Conn's syndrome converts to ICD-9-CM 255.12 (Conn's syndrome). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.