How to Find ICD Codes for Diagnosis

International Classification of Diseases (ICD) codes can be found on patient paperwork, including hospital records, medical records, visit summaries, and bills. These codes ensure that you receive appropriate treatment and are billed correctly for any medical services you receive.

The 10th edition of the code, which has been in use since 2015, is called ICD-10 and contains more than 70,000 disease codes. The ICD is maintained by the World Health Organization (WHO) and distributed in countries around the world.

This article describes how medical professionals use ICD codes, how codes continue to be updated, and how to find them when needed.

How to use ICD codes

In the United States, ICD codes are overseen by the Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS).

The ICD receives annual updates between revisions, which are sometimes reflected in the code headings. For example, the updated version for 2020 is ICD-10-CM. The ICD-11 was approved by the World Health Organization in 2019, so it could enter into force in 2022.

ICD codes are used for billing, treatment and statistical data collection. Having the correct code is important to ensure that standardized treatment for medical problems is provided and that medical expenses are reimbursed.

Insurance reimbursement

When your healthcare provider submits a claim form to an insurance company for reimbursement, each service is described by a Common Procedural Technology (CPT) code. It matches the ICD code. If the two codes are not properly aligned with each other, the company may refuse payment.

In other words, the insurance company won’t pay for the service if it’s not something that would normally be offered to someone with that diagnosis.

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For example, if you complain of a rash, your healthcare provider should not submit an X-ray order because the question does not indicate imaging.

Understand insurance codes to avoid billing errors

disease management

Each disease has an ICD code. If you have a chronic medical condition, such as diabetes or heart disease, your ICD code will usually follow your medical record.

In a hospital setting, this can save lives. But it can be frustrating for chronically ill patients who come to the hospital for unrelated problems.

When you meet a new health care provider, they may start by asking questions about chronic conditions rather than focusing on the reasons for your hospitalization. However, while a condition may not concern you, there may be a connection known only to your doctor.

This process makes sense when you consider that about 80% of “older people” have at least one chronic health condition, and 50% have two or more.

Still, this reality can sometimes lead providers to order unnecessary testing and treatment for chronic conditions, rather than focusing on the problem that led you to seek treatment.

Other uses

ICD codes are used globally to track health statistics and causes of death. This helps collect data on chronic and new diseases. For example, a new code was added to ICD-10 in 2020 to track vaping-related illnesses.

ICD codes are also used in clinical trials to recruit and track subjects and are sometimes (but not always) included on death certificates.

ICD code update

The 2015 revision of the ICD involved many changes. Therefore, ICD-10 codes are handled differently than ICD-9 codes.

ICD-9 code

Although obsoleted in 2015, the ICD-9 code still appears in older files. Most ICD-9 codes are three digits to the left of the decimal point and one or two digits to the right. E.g:

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  • 250.0 is diabetes without complications.
  • 530.81 is gastroesophageal reflux disease (GERD).
  • 079.99 is a virus.

Some ICD-9 codes are preceded by a “V” or “E”. The “V” code is for health services that do not require a diagnosis (usually preventive). The “E” code describes the environmental cause of a health problem, such as injury or poisoning.

ICD-10 code

The ICD-10 update revolutionized the encoding system. The new codes (over 14,000 in total) are divided into chapters and sub-chapters and consist of a letter plus two digits to the left of the decimal point, then one digit to the right.

The new system allows for more specific diagnostics. E.g:

  • E10.9 is type 1 diabetes and E11.9 is type 2 diabetes.
  • K21.9 is GERD.
  • B97.89 is a virus classified as a cause of disease elsewhere.

These letters group diseases together and describe the characteristics of a specific condition, organ system, or condition. This may cause initial confusion, as the “E” no longer stands for environmental causes, but endocrine disorders.

ICD-10 Diagnostic Codes from A to Z

  • A: Infectious and parasitic diseases
  • B: Infectious and parasitic diseases
  • C: cancer
  • D: Tumors, blood and hematopoietic organs
  • E: Endocrine, Nutritional or Metabolic
  • F: Mental and behavioral disorders
  • G: nervous system
  • H: eyes, ears, nose and throat
  • One: circulatory system
  • J: respiratory system
  • K: Digestive system
  • L: skin
  • M: Musculoskeletal System
  • N: genitourinary system
  • O: Pregnancy and childbirth
  • P: Perinatal status
  • Q: Congenital and chromosomal abnormalities
  • R: Abnormal clinical and laboratory findings
  • S: External causes such as trauma, poisoning, etc.
  • T: External causes such as trauma, poisoning, etc.
  • U: for emergency designation
  • Five: the external cause of the disease
  • W: External causes of morbidity
  • X: External causes of morbidity
  • Y: External causes of morbidity
  • Z: Factors affecting health status and exposure to health services

ICD-11 code

In 2022, the ICD code will change again, adding two numbers – one before the letter and one at the end. For example, X98.6 (ICD-10 code) will become 0X98.60.

The updated code also does not use the letters “I” or “O” to avoid confusion with 1s and 0s.

Where to find ICD codes

When you leave your healthcare provider’s appointment, treatment appointment, or hospital, you’ll receive a visit summary with a different code. Your ICD code is listed under “Diagnostics” or “Dx”, while the other codes are usually the CPT codes for the services provided.

When you receive an Statement of Benefit (EOB) from an insurance company, Medicare, or other payer, it also contains the ICD code.

If a claim is disputed or not paid, it may be because the ICD code does not match the CPT code. If this happens, talk to someone in your healthcare provider’s billing department.

If you need to find the ICD code for a specific diagnosis or to confirm what the ICD code stands for, visit the US Centers for Disease Control and Prevention (CDC) website to use its searchable database of current ICD-10 codes.


The International Classification of Diseases (ICD) is a tool for assigning codes (a medical shorthand) to diseases, signs and symptoms, abnormal findings, circumstances, and external causes of illness or injury. Insurance companies want codes to be consistent across illnesses and treatments. Otherwise, they may be reluctant to pay. That’s reason enough to learn how to find them yourself.