2026 ICD-10-CM Diagnosis Code T46.4X5AAdverse effect of angiotensin-converting-enzyme inhibitors, initial encounter
T46.4X5A is a billable ICD-10-CM diagnosis code for adverse effect of angiotensin-converting-enzyme inhibitors, 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. 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 Adverse effects of drugs and medicaments, initial encounter.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for T46.4X5A.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- ACE inhibitor-aggravated angioedema
- Acute renal failure caused by angiotensin-converting-enzyme inhibitor
- Adverse reaction caused by losartan
- Angioedema caused by angiotensin-converting-enzyme inhibitor
- Angioedema due to disorder of kinin metabolism
- Angiotensin II receptor antagonist adverse reaction
- Angiotensin-converting-enzyme inhibitor adverse reaction
- Captopril adverse reaction
- Cilazapril adverse reaction
- Drug-induced hyperkalemia
- Edema of intestinal tract
- Enalapril adverse reaction
- Fosinopril adverse reaction
- Hyperkalemia
- Hyperkalemia caused by angiotensin-converting enzyme inhibitor
- Intestinal angioedema caused by angiotensin-converting enzyme inhibitor
- Lisinopril adverse reaction
- Nephrotoxic acute renal failure
- Perindopril adverse reaction
- Quinapril adverse reaction
- Ramipril adverse reaction
- Trandolapril adverse reaction
Coding GuidelinesGuidance
When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.
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
Hyperkalemia
abnormally high potassium concentration in the blood, most often due to defective renal excretion. it is characterized clinically by electrocardiographic abnormalities (elevated t waves and depressed p waves, and eventually by atrial asystole). in severe cases, weakness and flaccid paralysis may occur. (dorland, 27th ed)Pseudohypoaldosteronism
a heterogeneous group of disorders characterized by renal electrolyte transport dysfunctions. congenital forms are rare autosomal disorders characterized by neonatal hypertension, hyperkalemia, increased renin activity and aldosterone concentration. the type i features hyperkalemia with sodium wasting; type ii, hyperkalemia without sodium wasting. pseudohypoaldosteronism can be the result of a defective renal electrolyte transport protein or acquired after kidney transplantation.Grade 1 Hyperkalemia, CTCAE|Grade 1 Hyperkalemia
>uln - 5.5 mmol/lGrade 2 Hyperkalemia, CTCAE|Grade 2 Hyperkalemia
>5.5 - 6.0 mmol/l; intervention initiatedGrade 3 Hyperkalemia, CTCAE|Grade 3 Hyperkalemia
>6.0 - 7.0 mmol/l; hospitalization indicatedGrade 1 Hyperkalemia, CTCAE|Grade 1 Hyperkalemia
>uln-5.5 mmol/lGrade 2 Hyperkalemia, CTCAE|Grade 2 Hyperkalemia
>5.5-6.0 mmol/l; intervention initiatedGrade 3 Hyperkalemia, CTCAE|Grade 3 Hyperkalemia
>6.0-7.0 mmol/l; hospitalization indicatedGrade 4 Hyperkalemia, CTCAE|Grade 4 Hyperkalemia
>7.0 mmol/l; life-threatening consequencesGrade 5 Hyperkalemia, CTCAE|Grade 5 Hyperkalemia
deathHyperkalemia
higher than normal levels of potassium in the circulating blood; associated with kidney failure or sometimes with the use of diuretic drugs.Hyperkalemia, CTCAE|Hyperkalemia|Hyperkalemia
a disorder characterized by laboratory test results that indicate an elevation in the concentration of potassium in the blood; associated with kidney failure or sometimes with the use of diuretic drugs.Hyperkalemic Mineralocorticoid Resistance|Chloride Shunt Syndrome|Familial Hyperkalemic Hypertension|Gordon Hyperkalemia|Mineralocorticoid Resistant Hyperkalemia|PHA Type 2|Pseudohypoaldosteronism, Type II|Spitzer-Weinstein Syndrome
a genetically heterogynous condition characterized by hyperkalemia, hyperchloremic acidosis, low or suppressed renin activity, and normal to high concentrations of aldosterone. mutations in genes (for example wnk1 or wnk4), regulating na-cl cotransporters (ncc), na-k-cl cotransporters (nkcc2), or the renal outer medullary potassium (romk) channel have been identified as causative in this condition. the primary abnormality is thought to be a specific defect of the renal secretory mechanism for potassium, which limits the kaliuretic response to, but not the sodium and chloride reabsorptive effect of, mineralocorticoid.Hyperkalemic Mineralocorticoid Resistance|Chloride Shunt Syndrome|Familial Hyperkalemic Hypertension|Gordon Hyperkalemia|Mineralocorticoid Resistant Hyperkalemia|PHA Type 2|Pseudohypoaldosteronism, Type II|Spitzer-Weinstein Syndrome
a genetically heterogenous condition characterized by hyperkalemia, hyperchloremic acidosis, low or suppressed renin activity, and normal to high concentrations of aldosterone. mutations in genes (for example wnk1 or wnk4), regulating na-cl cotransporters (ncc), na-k-cl cotransporters (nkcc2), or the renal outer medullary potassium (romk) channel have been identified as causative in this condition. the primary abnormality is thought to be a specific defect of the renal secretory mechanism for potassium, which limits the kaliuretic response to, but not the sodium and chloride reabsorptive effect of, mineralocorticoid.
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
Drug Reactions
Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.
The full article covers:
- What is a drug interaction?
- What are side effects?
- What are drug allergies?
- How can I stay safe when taking medicines?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T46.4X5A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T46.4X5AOverview
Is T46.4X5A (Adverse effect of angiotensin-converting-enzyme inhibitors) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of angiotensin-converting-enzyme inhibitors, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T46.4X5A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for adverse effect of angiotensin-converting-enzyme inhibitors, such as an emergency visit or first evaluation.
What MS-DRG does T46.4X5A group to?
On inpatient claims, adverse effect of angiotensin-converting-enzyme inhibitors, initial encounter maps to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
Can T46.4X5A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of angiotensin-converting-enzyme inhibitors, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
What is the ICD-9 equivalent of T46.4X5A?
Under the General Equivalence Mappings, adverse effect of angiotensin-converting-enzyme inhibitors, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E942.6 (adv eff antihyperten agt). The mapping is approximate, so confirm the match fits the documentation.
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.
