2026 ICD-10-CM Diagnosis Code T38.6X6AUnderdosing of antigonadotrophins, antiestrogens, antiandrogens, not elsewhere classified, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T38

ICD-10-CM T38.6X6A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T38.6X6A is a billable ICD-10-CM diagnosis code for underdosing of antigonadotrophins, antiestrogens, antiandrogens, not elsewhere classified, 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

ICD-10-CM Code
T38.6X6A
Billable Status
Yes — Valid for Submission
Code Describes
Underdosing of antigonadotrophins, antiestrogens, antiandrogens, not elsewhere classified, initial encounter
Short Description
Underdosing of antigonadtr/antiestr/antiandrg, NEC, init
Parent Code
T38.6X6
Underdosing of antigonadotrophins, antiestrogens, antiandrogens, not elsewhere classified

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT36-T50Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances
CategoryT38Poisoning by, adverse effect of and underdosing of hormones and their synthetic substitutes and antagonists, not elsewhere classified
This CodeT38.6X6AUnderdosing of antigonadotrophins, antiestrogens, antiandrogens, not elsewhere classified, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T38.6X6A.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

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 hormones and their synthetic substitutes and antagonists, not elsewhere classified (T38). 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 INJ029
Underdosing of drugs and medicaments, initial encounter
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Cyproterone

    an anti-androgen that, in the form of its acetate (cyproterone acetate), also has progestational properties. it is used in the treatment of hypersexuality in males, as a palliative in prostatic carcinoma, and, in combination with estrogen, for the therapy of severe acne and hirsutism in females.

  • Cyproterone Acetate

    an agent with anti-androgen and progestational properties. it shows competitive binding with dihydrotestosterone at androgen receptor sites.

  • Danazol

    a synthetic steroid with antigonadotropic and anti-estrogenic activities that acts as an anterior pituitary suppressant by inhibiting the pituitary output of gonadotropins. it possesses some androgenic properties. danazol has been used in the treatment of endometriosis and some benign breast disorders.

  • Flutamide

    an antiandrogen with about the same potency as cyproterone in rodent and canine species.

  • Mifepristone

    a progestational and glucocorticoid hormone antagonist. its inhibition of progesterone induces bleeding during the luteal phase and in early pregnancy by releasing endogenous prostaglandins from the endometrium or decidua. as a glucocorticoid receptor antagonist, the drug has been used to treat hypercortisolism in patients with nonpituitary cushing syndrome.

  • Nafoxidine

    an estrogen antagonist that has been used in the treatment of breast cancer.

  • Tamoxifen

    one of the selective estrogen receptor modulators with tissue-specific activities. tamoxifen acts as an anti-estrogen (inhibiting agent) in the mammary tissue, but as an estrogen (stimulating agent) in cholesterol metabolism, bone density, and cell proliferation in the endometrium.

  • Toremifene

    a first generation selective estrogen receptor modulator (serm). like tamoxifen, it is an estrogen agonist for bone tissue and cholesterol metabolism but is antagonistic on mammary and uterine tissue.

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
Antiandrogen NECT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
Antiestrogen NECT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
Antigonadotrophin NECT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
CyproteroneT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
DanazolT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
FlutamideT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
MifepristoneT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
NafoxidineT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
NilutamideT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
OrmeloxifeneT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
TaleranolT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
TamoxifenT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6
ToremifeneT38.6X1T38.6X2T38.6X3T38.6X4T38.6X5T38.6X6

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 T38.6X6A to ICD-9-CMHistory

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

ICD-9-CM
No Map There is no ICD-9 equivalent for this code.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About T38.6X6AOverview

Is T38.6X6A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of antigonadotrophins, antiestrogens, antiandrogens, not elsewhere classified, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T38.6X6A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of antigonadotrophins, antiestrogens, antiandrogens, not elsewhere classified, such as an emergency visit or first evaluation.

Can T38.6X6A be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of antigonadotrophins, antiestrogens, antiandrogens, not elsewhere classified, 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.