2026 ICD-10-CM Diagnosis Code T46.6X6AUnderdosing of antihyperlipidemic and antiarteriosclerotic drugs, initial encounter
T46.6X6A is a billable ICD-10-CM diagnosis code for underdosing of antihyperlipidemic and antiarteriosclerotic drugs, 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 T46.6X6A.
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 agents primarily affecting the cardiovascular system (T46). 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
Bezafibrate
an antilipemic agent that lowers cholesterol and triglycerides. it decreases low density lipoproteins and increases high density lipoproteins.Clofibrate
a fibric acid derivative used in the treatment of hyperlipoproteinemia type iii and severe hypertriglyceridemia. (from martindale, the extra pharmacopoeia, 30th ed, p986)Colestipol
highly crosslinked and insoluble basic anion exchange resin used as anticholesteremic. it may also may reduce triglyceride levels.Fenofibrate
an antilipemic agent which reduces both cholesterol and triglycerides in the blood.Gemfibrozil
a lipid-regulating agent that lowers elevated serum lipids primarily by decreasing serum triglycerides with a variable reduction in total cholesterol.Halofenate
an antihyperlipoproteinemic agent and uricosuric agent.Linoleic Acid
a doubly unsaturated fatty acid, occurring widely in plant glycosides. it is an essential fatty acid in mammalian nutrition and is used in the biosynthesis of prostaglandins and cell membranes. (from stedman, 26th ed)Linoleic Acids
eighteen-carbon essential fatty acids that contain two double bonds.Linoleic Acids, Conjugated
a collective term for a group of around nine geometric and positional isomers of linoleic acid in which the trans/cis double bonds are conjugated, where double bonds alternate with single bonds.Linoleoyl-CoA Desaturase
an enzyme that catalyzes the syn-dehydrogenation of linoleol-coa gamma-linolenoyl-coa. it was formerly characterized as ec 1.14.99.25.Lovastatin
a fungal metabolite isolated from cultures of aspergillus terreus. the compound is a potent anticholesteremic agent. it inhibits 3-hydroxy-3-methylglutaryl coenzyme a reductase (hydroxymethylglutaryl coa reductases), which is the rate-limiting enzyme in cholesterol biosynthesis. it also stimulates the production of low-density lipoprotein receptors in the liver.Oleic Acid
an unsaturated fatty acid that is the most widely distributed and abundant fatty acid in nature. it is used commercially in the preparation of oleates and lotions, and as a pharmaceutical solvent. (stedman, 26th ed)Oleic Acids
a group of fatty acids that contain 18 carbon atoms and a double bond at the omega 9 carbon.Ricinoleic Acids
eighteen carbon fatty acids that comprise the great majority of castor oil, which is from the seed of ricinus.Pravastatin
an antilipemic fungal metabolite isolated from cultures of nocardia autotrophica. it acts as a competitive inhibitor of hmg coa reductase (hydroxymethylglutaryl coa reductases).Probucol
a drug used to lower ldl and hdl cholesterol yet has little effect on serum-triglyceride or vldl cholesterol. (from martindale, the extra pharmacopoeia, 30th ed, p993).Safflower Oil
an oily liquid extracted from the seeds of the safflower, carthamus tinctorius. it is used as a dietary supplement in the management of hypercholesterolemia. it is used also in cooking, as a salad oil, and as a vehicle for medicines, paints, varnishes, etc. (dorland, 28th ed & random house unabridged dictionary, 2d ed)Simvastatin
a derivative of lovastatin and potent competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme a reductase (hydroxymethylglutaryl coa reductases), which is the rate-limiting enzyme in cholesterol biosynthesis. it may also interfere with steroid hormone production. due to the induction of hepatic ldl receptors, it increases breakdown of ldl cholesterol.Sitosterols
a family of sterols commonly found in plants and plant oils. alpha-, beta-, and gamma-isomers have been characterized.Triparanol
antilipemic agent with high ophthalmic toxicity. according to merck index, 11th ed, the compound was withdrawn from the market in 1962 because of its association with the formation of irreversible cataracts.
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 T46.6X6A to ICD-9-CMHistory
Code HistoryHistory
Questions About T46.6X6AOverview
Is T46.6X6A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report underdosing of antihyperlipidemic and antiarteriosclerotic drugs, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T46.6X6A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for underdosing of antihyperlipidemic and antiarteriosclerotic drugs, such as an emergency visit or first evaluation.
Can T46.6X6A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because underdosing of antihyperlipidemic and antiarteriosclerotic drugs, 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.
