2027 ICD-10-CM Diagnosis Code E24.3Ectopic ACTH syndrome

ICD-10-CM Codes›E00–E89›E20-E35›E24

ICD-10-CM E24.3
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

E24.3 is a billable ICD-10-CM diagnosis code for ectopic ACTH syndrome. 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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 23 closely related codes. Coders also document this condition as ectopic ACTH secretion. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified endocrine disorders.

E24.3 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
E24.3
Billable Status
Yes — Valid for Submission
Code Describes
Ectopic ACTH syndrome
Short Description
Ectopic ACTH syndrome
Same as the full description in the CMS dataset.
Parent Code
E24
Cushing's syndrome

Code Classification

ChapterE00–E89Endocrine, nutritional and metabolic diseases
SectionE20-E35Disorders of other endocrine glands
CategoryE24Cushing's syndrome
This CodeE24.3Ectopic ACTH syndrome

Medicare Risk Adjustment (HCC)Billing

E24.3 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.

  • Ectopic ACTH secretion
  • Hypercortisolism due to nonpituitary neoplasm
  • Paraneoplastic ectopic secretion of ACTH

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to E24.3: its own notes plus those printed at E24, 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 E24 Cushing's syndrome applies to 7 codes
  • congenital adrenal hyperplasia (E25.0)
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)

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 E24.3, its category, or a range that includes it.

Excludes1 3

These codes carry an Excludes1 note naming E24.3: they are not reported together with it, unless the two conditions are unrelated.

  • E34.2 Ectopic hormone secretion, not elsewhere classified
    ectopic ACTH syndrome (E24.3)
  • E22 Hyperfunction of pituitary gland
    Cushing's syndrome (E24.-) names E24.-, which includes this code
  • E27.0 Other adrenocortical overactivity
    Cushing's syndrome (E24.-) names E24.-, which includes this code

Code First 2

These codes say to code first a condition named in the note, and E24.3 is one of the conditions named.

  • E08 Diabetes mellitus due to underlying condition
    Cushing's syndrome (E24.-) names E24.-, 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 E24.3.

  • 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

  • ACTH Syndrome, Ectopic

    symptom complex due to acth production by non-pituitary neoplasms.

Patient EducationClinical

Cushing's Syndrome

Cushing's syndrome is a hormonal disorder. The cause is long-term exposure to too much cortisol, a hormone that your adrenal gland makes. Sometimes, taking synthetic hormone medicine to treat an inflammatory disease leads to Cushing's. Some kinds of tumors produce a hormone that can cause your body to make too much cortisol.

Read the full article at MedlinePlus

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

Convert E24.3 to ICD-9-CMHistory

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

ICD-9-CM
255.0 Cushing's syndrome
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About E24.3Overview

What is the ICD-10 code for ectopic ACTH syndrome?

The ICD-10-CM code for ectopic ACTH syndrome is E24.3 (sometimes written as E243). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is E24.3 (Cushing's syndrome) a billable code?

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

What MS-DRG does E24.3 group to?

When ectopic ACTH syndrome 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.

Is E24.3 a CC or MCC?

CMS lists E24.3 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 23 closely related codes in its exclusion list.

Can E24.3 be reported with E25.0?

Not as a rule. The Excludes1 note at E24, which applies to E24.3, lists "congenital adrenal hyperplasia (E25.0)". 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).

Does E24.3 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. E24.3 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).