2027 ICD-10-CM Diagnosis Code Z17.420Hormone receptor negative with human epidermal growth factor receptor 2 positive status
Z17.420 is a billable ICD-10-CM diagnosis code for hormone receptor negative with human epidermal growth factor receptor 2 positive status. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 951. The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Genetic susceptibility to disease.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for Z17.420.
Present on Admission (POA)Billing
Z17.420 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Estrogen, and other hormones and factors receptor status (Z17).
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Z17.420: its own notes plus those printed at Z17.4, Z17, and Chapter 21. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- HR- with HER2+
Code First
The underlying condition named in the note is sequenced before this code.
Notes
General instructions on how these codes are used.
- Assign a code from subcategory Z17.4- when only a combined receptor status is documented
- Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
- (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
- (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Z17.420, its category, or a range that includes it.
Use Additional Code 1
These codes say to use an additional code from the note, and Z17.420 is one of the codes named.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Status (post) See Also: Presence (of);
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Code HistoryHistory
Questions About Z17.420Overview
Is Z17.420 (Hormone receptor negative) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report hormone receptor negative with human epidermal growth factor receptor 2 positive status on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Z17.420 group to?
On inpatient claims, hormone receptor negative with human epidermal growth factor receptor 2 positive status maps to MS-DRG 951 (other Factors Influencing Health Status), which carries a relative weight of 0.5574. Higher weights mean higher Medicare reimbursement.
Can Z17.420 be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because hormone receptor negative with human epidermal growth factor receptor 2 positive status describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
Is Z17.420 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for hormone receptor negative with human epidermal growth factor receptor 2 positive status on inpatient claims. The code appears in the Estrogen, and other hormones and factors receptor status (Z17) range of the CMS exempt list.
