2026 ICD-10-CM Diagnosis Code T44.4X6AUnderdosing of predominantly alpha-adrenoreceptor agonists, initial encounter
T44.4X6A is a billable ICD-10-CM diagnosis code for underdosing of predominantly alpha-adrenoreceptor agonists, 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 T44.4X6A.
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 drugs primarily affecting the autonomic nervous system (T44). 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
Etilefrine
a phenylephrine-related beta-1 adrenergic and alpha adrenergic agonist used as a cardiotonic and antihypotensive agent.Metaraminol
a sympathomimetic agent that acts predominantly at alpha-1 adrenergic receptors. it has been used primarily as a vasoconstrictor in the treatment of hypotension.Methoxamine
an alpha-1 adrenergic agonist that causes prolonged peripheral vasoconstriction.Norepinephrine
precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the locus ceruleus. it is also found in plants and is used pharmacologically as a sympathomimetic.Norepinephrine Plasma Membrane Transport Proteins
sodium chloride-dependent neurotransmitter symporters located primarily on the plasma membrane of noradrenergic neurons. they remove norepinephrine from the extracellular space by high affinity reuptake into presynaptic terminals. the norepinephrine transporter regulates signal amplitude and duration at noradrenergic synapses and is the target of adrenergic uptake inhibitors.Phenylethanolamine N-Methyltransferase
a methyltransferase that catalyzes the reaction of s-adenosyl-l-methionine and phenylethanolamine to yield s-adenosyl-l-homocysteine and n-methylphenylethanolamine. it can act on various phenylethanolamines and converts norepinephrine into epinephrine. (from enzyme nomenclature, 1992) ec 2.1.1.28.Receptors, Adrenergic
cell-surface proteins that bind epinephrine and/or norepinephrine with high affinity and trigger intracellular changes. the two major classes of adrenergic receptors, alpha and beta, were originally discriminated based on their cellular actions but now are distinguished by their relative affinity for characteristic synthetic ligands. adrenergic receptors may also be classified according to the subtypes of g-proteins with which they bind; this scheme does not respect the alpha-beta distinction.Phenylephrine
an alpha-1 adrenergic agonist used as a mydriatic, nasal decongestant, and cardiotonic agent.
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 T44.4X6A to ICD-9-CMHistory
Code HistoryHistory
Questions About T44.4X6AOverview
Is T44.4X6A (Underdosing of predominantly alpha-adrenoreceptor agonists) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of predominantly alpha-adrenoreceptor agonists, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T44.4X6A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of predominantly alpha-adrenoreceptor agonists, such as an emergency visit or first evaluation.
Can T44.4X6A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of predominantly alpha-adrenoreceptor agonists, 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.
