ICD-10-CM Diagnosis Code E51.9 - Thiamine deficiency, unspecified (original) (raw)

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ICD List 2025-2026 Edition

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  6. 2026 ICD-10-CM Code E51.9

Thiamine deficiency, unspecified

ICD-10-CM Code:

E51.9

ICD-10 Code for:

Thiamine deficiency, unspecified

Is Billable?

Yes - Valid for Submission

Chronic Condition Indicator: [1]

Not chronic

Code Navigator:

E51.9 is a billable diagnosis code used to specify a medical diagnosis of thiamine deficiency, unspecified. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2025 through September 30, 2026.

Unspecified diagnosis codes like E51.9 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.

  1. Code Information
  2. Approximate Synonyms
  3. Clinical Classification
  4. Clinical Information
  5. Tabular List of Diseases and Injuries
  6. Index to Diseases and Injuries References
  8. Diagnostic Related Groups Mapping
  9. Convert to ICD-9 Code
  10. Patient Education
  11. Other Codes Used Similar Conditions
  12. Code History

The following list of clinical terms are approximate synonyms, alternative descriptions, or common phrases that might be used by patients, healthcare providers, or medical coders to describe the same condition. These synonyms and related diagnosis terms are often used when searching for an ICD-10 code, especially when the exact medical terminology is unclear. Whether you're looking for lay terms, similar diagnosis names, or common language alternatives, this list can help guide you to the correct ICD-10 classification.

Clinical Classifications group individual ICD-10-CM diagnosis codes into broader, clinically meaningful categories. These categories help simplify complex data by organizing related conditions under common clinical themes.

They are especially useful for data analysis, reporting, and clinical decision-making. Even when diagnosis codes differ, similar conditions can be grouped together based on their clinical relevance. Each category is assigned a unique CCSR code that represents a specific clinical concept, often tied to a body system or medical specialty.

CCSR Code: END007

Inpatient Default: Y - Yes, default inpatient assignment for principal diagnosis or first-listed diagnosis.

Outpatient Default: Y - Yes, default outpatient assignment for principal diagnosis or first-listed diagnosis.

a nutritional condition produced by a deficiency of thiamine in the diet, characterized by anorexia, irritability, and weight loss. later, patients experience weakness, peripheral neuropathy, headache, and tachycardia. in addition to being caused by a poor diet, thiamine deficiency in the united states most commonly occurs as a result of alcoholism, since ethanol interferes with thiamine absorption. in countries relying on polished rice as a dietary staple, beriberi prevalence is very high. (from cecil textbook of medicine, 19th ed, p1171)

References found for this diagnosis code in the External Cause of Injuries Index:

Below are the ICD-9 codes that most closely match this ICD-10 code, based on the General Equivalence Mappings (GEMs). This ICD-10 to ICD-9 crosswalk tool is helpful for coders who need to reference legacy diagnosis codes for audits, historical claims, or approximate code comparisons.

ICD-9-CM: 265.1

Approximate Flag - The approximate mapping means this ICD-10 code does not have an exact ICD-9 equivalent. The matched code is the closest available option, but it may not fully capture the original diagnosis or clinical intent.

B Vitamins

The B vitamins are:

These vitamins help the process your body uses to get or make energy from the food you eat. They also help form red blood cells. You can get B vitamins from proteins such as fish, poultry, meat, eggs, and dairy products. Leafy green vegetables, beans, and peas also have B vitamins. Many cereals and some breads have added B vitamins.

Not getting enough of certain B vitamins can cause diseases. A lack of B12 or B6 can cause anemia.

[Learn More in MedlinePlus]

Malnutrition

What is malnutrition?

Malnutrition means that your body isn't getting enough calories or the right balance of nutrients to stay healthy. This can happen if you don't get enough protein, carbohydrates, and fats, eat too much unhealthy food, or don't get the vitamins and minerals your body needs.

Malnutrition can affect people of all ages, but children, older adults, and people with chronic (long-term) health problems have a higher risk.

What are the types of malnutrition?

Most people think of undernutrition with malnutrition. But malnutrition can refer to undernutrition, overnutrition, or an imbalance of nutrients.

Types of malnutrition include:

What causes malnutrition?

Malnutrition may occur for many reasons, including:

Who is at risk for developing malnutrition?

Malnutrition can affect anyone, but some people have a higher risk than others. This includes people who:

What are the symptoms of malnutrition?

The symptoms of malnutrition can vary. You may have no symptoms, but if you do, they may include:

How is malnutrition diagnosed?

To check for malnutrition, your provider may:

What are the treatments for malnutrition?

Treatment for malnutrition may include improving your diet, replacing missing nutrients, and treating the underlying cause.

Can malnutrition be prevented?

To help prevent malnutrition, eat a healthy diet with many different foods. Talk with your provider if you are worried about your diet, weight loss, or your child's growth.

[Learn More in MedlinePlus]