2026 ICD-10-CM Diagnosis Code T56.823AToxic effect of gadolinium, assault, initial encounter

ICD-10-CM Codes›S00–T88›T51-T65›T56

ICD-10-CM T56.823A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T56.823A is a billable ICD-10-CM diagnosis code for toxic effect of gadolinium, assault, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, assault; External cause codes: poisoning by non-drug; and Toxic effects, initial encounter.

Code Identity

ICD-10-CM Code
T56.823A
Billable Status
Yes — Valid for Submission
Code Describes
Toxic effect of gadolinium, assault, initial encounter
Short Description
Toxic effect of gadolinium, assault, initial encounter
Same as the full description in the CMS dataset.
Parent Code
T56.823
Toxic effect of gadolinium, assault

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT51-T65Toxic effects of substances chiefly nonmedicinal as to source
CategoryT56Toxic effect of metals
This CodeT56.823AToxic effect of gadolinium, assault, initial encounter

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Toxic effect of metals (T56). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR EXT022
External cause codes: intent of injury, assault
Default principal diagnosis: inpatient No · outpatient No
CCSR EXT015
External cause codes: poisoning by non-drug
Default principal diagnosis: inpatient No · outpatient No
CCSR INJ023
Toxic effects, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Gadolinium

    an element of the rare earth family of metals. it has the atomic symbol gd, atomic number 64, and atomic weight 157.25. its oxide is used in the control rods of some nuclear reactors.

  • Gadolinium DTPA

    a complex of gadolinium with a chelating agent, diethylenetriamine penta-acetic acid (dtpa see pentetic acid), that is given to enhance the image in cranial and spinal mris. (from martindale, the extra pharmacopoeia, 30th ed, p706)

Table of Drugs and ChemicalsClinical

Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.

SubstanceAccidentalSelf-harmAssaultUndeter­minedAdverse
Effect		Under­dosing
GadoliniumT56.821T56.822T56.823T56.824––

Code History & ChangesHistory

Replacement T56.823A replaces the following previously assigned code(s):

  • T56.893A - Toxic effect of other metals, assault, initial encounter
FY 2024AddedAdded to the ICD-10-CM code setEffective October 1, 2023.
FY 2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About T56.823AOverview

Is T56.823A (Toxic effect of gadolinium, assault) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of gadolinium, assault, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T56.823A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for toxic effect of gadolinium, assault, such as an emergency visit or first evaluation.

What MS-DRG does T56.823A group to?

When toxic effect of gadolinium, assault, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.