2026 ICD-10-CM Diagnosis Code T50.6X6AUnderdosing of antidotes and chelating agents, initial encounter
T50.6X6A is a billable ICD-10-CM diagnosis code for underdosing of antidotes and chelating agents, 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). The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Underdosing of drugs and medicaments, initial encounter.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for T50.6X6A.
Coding GuidelinesGuidance
Underdosing refers to taking less of a medication than is prescribed by a provider or a manufacturer's instruction. Codes for underdosing should never be assigned as principal or first-listed codes. If a patient has a relapse or exacerbation of the medical condition for which the drug is prescribed because of the reduction in dose, then the medical condition itself should be coded.
The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substances (T50). 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.
Clinical InformationClinical
Cysteamine
a mercaptoethylamine compound that is endogenously derived from the coenzyme a degradative pathway. the fact that cysteamine is readily transported into lysosomes where it reacts with cystine to form cysteine-cysteamine disulfide and cysteine has led to its use in cystine depleting agents for the treatment of cystinosis.Disulfiram
a carbamate derivative used as an alcohol deterrent. it is a relatively nontoxic substance when administered alone, but markedly alters the intermediary metabolism of alcohol. when alcohol is ingested after administration of disulfiram, blood acetaldehyde concentrations are increased, followed by flushing, systemic vasodilation, respiratory difficulties, nausea, hypotension, and other symptoms (acetaldehyde syndrome). it acts by inhibiting aldehyde dehydrogenase.Glutathione
a tripeptide with many roles in cells. it conjugates to drugs to make them more soluble for excretion, is a cofactor for some enzymes, is involved in protein disulfide bond rearrangement and reduces peroxides.Glutathione Disulfide
a glutathione dimer formed by a disulfide bond between the cysteine sulfhydryl side chains during the course of being oxidized.Glutathione Peroxidase
an enzyme catalyzing the oxidation of 2 moles of glutathione in the presence of hydrogen peroxide to yield oxidized glutathione and water.Glutathione Peroxidase GPX1
one of the most abundant isoenzymes of the glutathione peroxidase family. located in the cytosol and mitochondria, it catalyzes the reduction of hydrogen peroxide to water, functioning to limit the accumulation of hydrogen peroxide and modulating processes that utilize hydrogen peroxide; and also the reduction of other organic hydroperoxides to their corresponding alcohols.Glutathione Reductase
catalyzes the oxidation of glutathione to glutathione disulfide in the presence of nadp+. deficiency in the enzyme is associated with hemolytic anemia. formerly listed as ec 1.6.4.2.Glutathione S-Transferase pi
a glutathione transferase that catalyzes the conjugation of electrophilic substrates to glutathione. this enzyme has been shown to provide cellular protection against redox-mediated damage by free radicals.Glutathione Synthase
one of the enzymes active in the gamma-glutamyl cycle. it catalyzes the synthesis of glutathione from gamma-glutamylcysteine and glycine in the presence of atp with the formation of adp and orthophosphate. ec 6.3.2.3.Glutathione Transferase
a transferase that catalyzes the addition of aliphatic, aromatic, or heterocyclic free radicals as well as epoxides and arene oxides to glutathione. addition takes place at the sulfur. it also catalyzes the reduction of polyol nitrate by glutathione to polyol and nitrite.Lactoylglutathione Lyase
an enzyme that catalyzes the interconversion of methylglyoxal and lactate, with glutathione serving as a coenzyme. ec 4.4.1.5.Phospholipid Hydroperoxide Glutathione Peroxidase
a selenoenzyme that converts glutathione plus fatty acid hydroperoxides to glutathione disulfide plus hydroxy fatty acids and water.Protein Disulfide Reductase (Glutathione)
an enzyme that catalyzes the reduction of a protein-disulfide in the presence of glutathione, forming a protein-dithiol. insulin is one of its substrates. ec 1.8.4.2.Obidoxime Chloride
cholinesterase reactivator occurring in two interchangeable isomeric forms, syn and anti.Penicillamine
3-mercapto-d-valine. the most characteristic degradation product of the penicillin antibiotics. it is used as an antirheumatic and as a chelating agent in wilson's disease.
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.
Patient EducationClinical
Medication Errors
Medicines treat infectious diseases, prevent problems from chronic diseases, and ease pain. But medicines can also cause harmful reactions if not used correctly. Errors can happen in the hospital, at the health care provider's office, at the pharmacy, or at home. You can help prevent errors by:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T50.6X6A to ICD-9-CMHistory
Code HistoryHistory
Questions About T50.6X6AOverview
Is T50.6X6A (Underdosing of antidotes and chelating agents) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of antidotes and chelating agents, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T50.6X6A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of antidotes and chelating agents, such as an emergency visit or first evaluation.
Can T50.6X6A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of antidotes and chelating agents, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
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.
