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

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for E26.01 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on E26.01 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for E26.01

MedCoder structured workflow — derived from this code’s own official record

Before you code E26.01

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with E26.01. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in E26.01’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewN64.3, N62

Consider E26.01. Then review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Official instructions as workflow

• Excludes1 — check before selecting E26.01(2 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with E26.01: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareN64.3, N62

  See the official tabular notes · Guidelines I.A.12.a

• Code Also — related condition(1 note)

  Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

  ReviewD35.0

  See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Conn's syndrome
• Syndrome, Conn's

Don’t confuse E26.01 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of E26.01 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• N64.3— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of galactorrhea moves the case to N64.3; the two are not reported together unless documented as unrelated.

  Full comparison: E26.01 vs N64.3 →

• N62— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of gynecomastia moves the case to N62; the two are not reported together unless documented as unrelated.

  Full comparison: E26.01 vs N62 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name E26.01 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Code First instruction: G63 — Polyneuropathy in diseases classified elsewhere (via E26.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 3 MS-DRGs: DRG 643 (MDC 10), DRG 644 (MDC 10), DRG 645 (MDC 10).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):END015 — Other specified and unspecified endocrine disorders (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other specified and unspecified endocrine disorders).

E21.5 — Disorder of parathyroid gland, unspecified, E24.1 — Nelson's syndrome, E24.2 — Drug-induced Cushing's syndrome, E24.3 — Ectopic ACTH syndrome, E24.4 — Alcohol-induced pseudo-Cushing's syndrome, E24.8 — Other Cushing's syndrome, E24.9 — Cushing's syndrome, unspecified, E25.0 — Congenital adrenogenital disorders associated with enzyme deficiency, E25.8 — Other adrenogenital disorders, E25.9 — Adrenogenital disorder, unspecified, E26.02 — Glucocorticoid-remediable aldosteronism, E26.09 — Other primary hyperaldosteronism, E26.1 — Secondary hyperaldosteronism, E26.81 — Bartter's syndrome, E26.89 — Other hyperaldosteronism, E26.9 — Hyperaldosteronism, unspecified, E27.0 — Other adrenocortical overactivity, E27.1 — Primary adrenocortical insufficiency, E27.2 — Addisonian crisis, E27.3 — Drug-induced adrenocortical insufficiency, +83 more

Contextual Map

Every relationship of E26.01 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run E26.01 with these 2 related codes in Claim Check

Hierarchy

• E00-E89 — Chapter 4: Endocrine, Nutritional and Metabolic Diseases (E00-E89) (E00-E89)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Code Also

• D35.0 — Benign neoplasm of adrenal gland[Code Also]: “adrenal adenoma (D35.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code First instructions

• G63 — Polyneuropathy in diseases classified elsewhere[Code First](via E26.-): “endocrine disease, except diabetes (E00-E07, E15-E16, E20-E34)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• END015 — Other specified and unspecified endocrine disorders[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• DRG 643 — ENDOCRINE DISORDERS WITH MCC[MS-DRG]: “ENDOCRINE DISORDERS WITH MCC (MDC 10)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 644 — ENDOCRINE DISORDERS WITH CC[MS-DRG]: “ENDOCRINE DISORDERS WITH CC (MDC 10)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 645 — ENDOCRINE DISORDERS WITHOUT CC/MCC[MS-DRG]: “ENDOCRINE DISORDERS WITHOUT CC/MCC (MDC 10)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 10 — Endocrine, Nutritional and Metabolic Diseases and Disorders[MDC crossing]: “Endocrine, Nutritional and Metabolic Diseases and Disorders — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 5,008 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Conn's syndrome[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Syndrome, Conn's[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (9)

• E26 — Hyperaldosteronism[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• E26.0 — Primary hyperaldosteronism[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• E26.02 — Glucocorticoid-remediable aldosteronism[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• E26.09 — Other primary hyperaldosteronism[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• E26.1 — Secondary hyperaldosteronism[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• E26.8 — Other hyperaldosteronism[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• E26.81 — Bartter's syndrome[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• E26.89 — Other hyperaldosteronism[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 1 more

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to E26.01 in its code family, with their registry titles.

• E26 — Hyperaldosteronism
• E26.0 — Primary hyperaldosteronism
• E26.02 — Glucocorticoid-remediable aldosteronism
• E26.09 — Other primary hyperaldosteronism
• E26.1 — Secondary hyperaldosteronism
• E26.8 — Other hyperaldosteronism
• E26.81 — Bartter's syndrome
• E26.89 — Other hyperaldosteronism
• E26.9 — Hyperaldosteronism, unspecified

View all codes in the E26 family