Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives: 1 inclusion term · 9 Excludes2 · 1 code-also instruction

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

MS-DRG 951 — OTHER FACTORS INFLUENCING HEALTH STATUS (MDC 23)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for Z77.123 in the official ICD-10-CM tabular list, quoted as published.

Notes without a marker are published on Z77.123 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

contact with and (suspected) exposures to potential hazards to health

Source: inherited from Z77

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

radiation exposure as the cause of a confirmed condition (W88-W90, X39.0-) Compare Z77.123 vs W88 →
radiation sickness NOS (T66) Compare Z77.123 vs T66 →
contact with and (suspected) exposure to communicable diseases (Z20.-) inherited from Z77Compare Z77.123 vs Z20 →
exposure to (parental) (environmental) tobacco smoke in the perinatal period (P96.81) inherited from Z77Compare Z77.123 vs P96.81 →
newborn affected by noxious substances transmitted via placenta or breast milk (P04.-) inherited from Z77Compare Z77.123 vs P04 →
occupational exposure to risk factors (Z57.-) inherited from Z77Compare Z77.123 vs Z57 →
retained foreign body (Z18.-) inherited from Z77Compare Z77.123 vs Z18 →
retained foreign body fully removed (Z87.821) inherited from Z77Compare Z77.123 vs Z87.821 →
toxic effects of substances chiefly nonmedicinal as to source (T51-T65) inherited from Z77Compare Z77.123 vs T51 →

Code Also

Additional codes that may be required to fully describe the encounter.

any follow-up examination (Z08-Z09)

Source: inherited from Z77-Z99

Coder workflow for Z77.123

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

Before you code Z77.123

Z77.123’s title joins a condition with an associated condition or complication. Confirm each component is documented. Where the classification presumes the link through the “with” convention, only a provider statement that the conditions are unrelated defeats it. A combination code is assigned only when it fully identifies the documented conditions; a required second code for the stage, type or manifestation is still reported when the notes ask for it (Guidelines I.B.9, I.A.15).
Guide: Combination codes →
Confirm the reason for the encounter this Z code records: the circumstance it records. Check whether the code may be reported as first-listed or principal — some Z codes are limited to one position — and do not report a history or status code for a condition documented as current. Z code categories and their reporting positions (Guidelines I.C.21.c, I.C.21.c.15).
Guide: Z codes as principal or first-listed diagnosis →

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).
The associated condition or complication: Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).
The reason for the encounter: Whether the code records the encounter’s purpose, a status, or a history — and whether it may be first-listed (Guidelines I.C.21.c).

Official instructions as workflow

Excludes2 — not part of Z77.123(9 notes)
Coding workflow: The conditions named in this note are not included in Z77.123. When the record documents both, both may be reported; the note is a boundary, not a prohibition.
CompareX39.0, T66, Z20, P96.81, P04, Z57
See the official tabular notes · Guidelines I.A.12.b
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.
See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

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

Documentation: Only one of the components this code’s title joins is documented.

Coding question: Is Z77.123 supported?

Path: Review the code for the documented component on its own.

Reason: A combination code is assigned only when it fully identifies the documented conditions; otherwise the documented component takes its own code (Guidelines I.B.9).

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.

Code Overview

Contact with and (suspected) exposure to radon and other naturally occurring radiation is a billable ICD-10-CM diagnosis code (Z77.123).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (4)

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.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Chapter 21: Factors influencing health status and contact with health services (Z00-Z99)

Category Z77, Other contact with and (suspected) exposures hazardous to health, indicates contact with and suspected exposures hazardous to health.

Don’t confuse Z77.123 with…

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

The codes most likely to be picked instead of Z77.123 — 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.

W88— Excludes2 relationship (Informational)
Distinct conditions — both may be reported.
A distinct condition — both may be reported when both are documented.
What moves you there: Documentation of radiation exposure as the cause of a confirmed condition adds W88; it is not part of this code and both may be reported when both are documented.
Full comparison: Z77.123 vs W88 →
W90— Excludes2 relationship (Informational)
Distinct conditions — both may be reported.
A distinct condition — both may be reported when both are documented.
What moves you there: Documentation of radiation exposure as the cause of a confirmed condition adds W90; it is not part of this code and both may be reported when both are documented.
Full comparison: Z77.123 vs W90 →
X39.0— Excludes2 relationship (Informational)
Distinct conditions — both may be reported.
A distinct condition — both may be reported when both are documented.
What moves you there: Documentation of radiation exposure as the cause of a confirmed condition adds X39.0; it is not part of this code and both may be reported when both are documented.
Full comparison: Z77.123 vs X39.0 →
T66— Excludes2 relationship (Informational)
Distinct conditions — both may be reported.
A distinct condition — both may be reported when both are documented.
What moves you there: Documentation of radiation sickness NOS adds T66; it is not part of this code and both may be reported when both are documented.
Full comparison: Z77.123 vs T66 →
Z20— Excludes2 relationship (Informational)
Distinct conditions — both may be reported.
A distinct condition — both may be reported when both are documented.
What moves you there: Documentation of contact with and (suspected) exposure to communicable diseases adds Z20; it is not part of this code and both may be reported when both are documented.
Full comparison: Z77.123 vs Z20 →
P96.81— Excludes2 relationship (Informational)
Distinct conditions — both may be reported.
A distinct condition — both may be reported when both are documented.
What moves you there: Documentation of exposure to (parental) (environmental) tobacco smoke in the perinatal period adds P96.81; it is not part of this code and both may be reported when both are documented.
Full comparison: Z77.123 vs P96.81 →

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

Principal-diagnosis restriction. The Medicare Code Editor lists this code as unacceptable as a principal diagnosis: it describes a circumstance influencing health status rather than a current illness or injury being treated. It is valid as a secondary diagnosis.

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 Z77.123 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.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 4 Excludes2 notes across 2 chapters: P04 — Newborn affected by noxious substances transmitted via placenta or breast milk (via Z77.-), Z59.1 — Inadequate housing (via Z77.1.-), Z91 — Personal risk factors, not elsewhere classified (via Z77.1.-), Z91 — Personal risk factors, not elsewhere classified (via Z77.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

Not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity.

Named in the grouper logic of 1 MS-DRG: DRG 951 (MDC 23).

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

Clinical classification (AHRQ CCSR):FAC025 — Other specified status (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

Principal diagnosis restriction (Medicare Code Editor)

Not acceptable as a principal diagnosis on an inpatient claim.

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other specified status).

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Exposure”, “Contact”; these codes share that main term but sit in a different category of the Tabular List.

Contextual Map

Every relationship of Z77.123 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 Z77.123 with these 16 related codes in Claim Check

Hierarchy

Z00-Z99 — Chapter 21: Factors Influencing Health Status and Contact with Health Services (Z00-Z99) (Z00-Z99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
Z77-Z99 — Persons with potential health hazards related to family and personal history and certain conditions influencing health status[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Excludes2

T66 — Radiation sickness, unspecified[Excludes2]: “radiation sickness NOS (T66)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
W88 — Exposure to ionizing radiation[Excludes2]: “radiation exposure as the cause of a confirmed condition (W88-W90, X39.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
W89 — Exposure to man-made visible and ultraviolet light[Excludes2]: “radiation exposure as the cause of a confirmed condition (W88-W90, X39.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
W90 — Exposure to other nonionizing radiation[Excludes2]: “radiation exposure as the cause of a confirmed condition (W88-W90, X39.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
X39.0 — Exposure to natural radiation[Excludes2]: “radiation exposure as the cause of a confirmed condition (W88-W90, X39.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes1 notes (19)

T51 — Toxic effect of alcohol[Excludes1](via Z77.-): “contact with and (suspected) exposure to toxic substances (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
T51-T65 — Toxic effects of substances chiefly nonmedicinal as to source (T51-T65)[Excludes1](via Z77.-): “contact with and (suspected) exposure to toxic substances (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
T52 — Toxic effect of organic solvents[Excludes1](via Z77.-): “contact with and (suspected) exposure to toxic substances (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
T53 — Toxic effect of halogen derivatives of aliphatic and aromatic hydrocarbons[Excludes1](via Z77.-): “contact with and (suspected) exposure to toxic substances (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
T54 — Toxic effect of corrosive substances[Excludes1](via Z77.-): “contact with and (suspected) exposure to toxic substances (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
T55 — Toxic effect of soaps and detergents[Excludes1](via Z77.-): “contact with and (suspected) exposure to toxic substances (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
T56 — Toxic effect of metals[Excludes1](via Z77.-): “contact with and (suspected) exposure to toxic substances (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
T57 — Toxic effect of other inorganic substances[Excludes1](via Z77.-): “contact with and (suspected) exposure to toxic substances (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
and 11 more

Referenced by Excludes2 notes

P04 — Newborn affected by noxious substances transmitted via placenta or breast milk[Excludes2](via Z77.-): “newborn in contact with and (suspected) exposures hazardous to health not transmitted via placenta or breast milk (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
Z59.1 — Inadequate housing[Excludes2](via Z77.1.-): “problems related to the natural and physical environment (Z77.1-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
Z91 — Personal risk factors, not elsewhere classified[Excludes2](via Z77.1.-): “exposure to pollution and other problems related to physical environment (Z77.1-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
Z91 — Personal risk factors, not elsewhere classified[Excludes2](via Z77.-): “contact with and (suspected) exposures hazardous to health (Z77.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

FAC025 — Other specified status[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

DRG 951 — OTHER FACTORS INFLUENCING HEALTH STATUS[MS-DRG]: “OTHER FACTORS INFLUENCING HEALTH STATUS (MDC 23)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

MDC 23 — Factors Influencing Health Status and Other Contacts with Health Services[MDC crossing]: “Factors Influencing Health Status and Other Contacts with Health Services — 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. 1,235 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

Contact (with), radiation, naturally occurring NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
Contact (with), radon[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
Exposure (to), radiation, naturally occurring NEC[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
Exposure (to), radon[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (40)

Z77 — Other contact with and (suspected) exposures hazardous to health[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
Z77.0 — Contact with and (suspected) exposure to hazardous, chiefly nonmedicinal, chemicals[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
Z77.01 — Contact with and (suspected) exposure to hazardous metals[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
Z77.010 — Contact with and (suspected) exposure to arsenic[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
Z77.011 — Contact with and (suspected) exposure to lead[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
Z77.012 — Contact with and (suspected) exposure to uranium[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
Z77.013 — Contact with and (suspected) exposure to gadolinium[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
Z77.018 — Contact with and (suspected) exposure to other hazardous metals[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
and 32 more

Change history (3)

FY2019 — Description revised[Change history]— CMS release files (code change ledger) · icd10cm-fy2019
and 2 more

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
Coding guidelines Official source data: ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section 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

Change history

FY2019 — October 1, 2018
Description revised
Contact with and (suspected) exposure to radon and other naturally occuring radiation → Contact with and (suspected) exposure to radon and other naturally occurring radiation
FY2019 changes
FY2019 — October 1, 2018
Short description revised
Cntct w & expsr to radon & oth naturally occuring radiation → Cntct w & expsr to radon and other naturally occur radiation
FY2019 changes
FY2016 — October 1, 2015
In the code set at ICD-10-CM adoption
Contact with and (suspected) exposure to radon and other naturally occuring radiation

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Z77.123 in its code family, with their registry titles.

View all codes in the Z77 family

Z77.123 ICD-10-CM Code: Contact with and (suspected) exposure to radon and other naturally occurring radiation