What Are ICD-10 Codes?

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Healthcare reimbursement is contingent on accurate coding. Therefore, a system has been designed that describes a person's medical condition/diagnosis and the list of services and tests provided. The codes must apply across all payers, no matter if they are federal or private insurance plans.

To this end, Healthcare Finance Administration Common Procedural Coding System (HCPC) codes identify the test or service the person received, while the ICD-10 (International Classification of Disease) codes describe the person's condition or diagnosis.

The ICD-10—also known as the International Classification of Diseases, 10th Revision—is the World Health Organization's (WHO) medical coding system for labeling diseases. The WHO creates these codes, which become modified by U.S. government agencies overseen by the Centers for Disease Control and Prevention (CDC).

The WHO began overseeing the ICD coding system in 1948, and the 10th revision was released in 2015. Note that an 11th revision was approved on January 1, 2022, and was pending until modifications were made.

All ICD-10 codes can be found online on the WHO website. This article details what the ICD-10 is used for and why it is useful for healthcare facilities, consumers, scientists, and government entities.

ICD-10 Codes

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The ICD-10 Coding Format

ICD-10 codes contain three to seven characters. They begin with a capital letter and a number (with single digits beginning with 0). The letter and number of the condition are followed by a decimal and either numbers or letters.

For example, ICD-10 codes J09 to J18 cover influenza (the flu) and pneumonia, respectively. The types of flu are labeled with numbers indicating factors like whether the strain of flu virus is yet to be identified and whether the virus was accompanied by pneumonia or other respiratory conditions. For example:

  • J10: Influenza due to identified seasonal influenza virus
  • J10.0: Influenza with pneumonia, seasonal influenza virus identified
  • J10.1: Influenza with other respiratory manifestations, seasonal influenza virus identified
  • J11: Influenza, virus not identified
  • J11.0: Influenza with pneumonia, virus not identified
  • J11.1: Influenza with other respiratory manifestations, seasonal influenza virus not identified

These flu-related ICD-10 codes could be a way to gather data on a strain of flu and how and where it affects the population. They are also a way to clearly diagnose patients while listing any treatment methods and charges incurred or able to be reimbursed by insurance.

Other ICD-10 codes can range from simple to complex, such as:

  • G10: Huntington's disease
  • M80.021G: Age-related osteoporosis with current pathological fracture, right humerus; subsequent encounter for fracture with delayed healing (or, in other words, osteoporosis of old age with a repeated upper right arm fracture that is taking long to heal).

What Information Do ICD-10 Codes Provide?

ICD-10 codes not only name diseases, but they also describe them, as follows:

  • Comorbidities: These are names of other diseases associated with the labeled condition. For example, flu might come with pneumonia or other respiratory diseases.
  • Where affected: With tumors, for example, ICD-10 codes provide information on the tumor location (C76.2 is the code for an abdominal tumor, while C44.509 is a tumor in the abdominal cavity wall, for example).
  • Severity: An ICD-10 code could also designate whether a tumor is malignant (C80.10) or benign (D36.9).
  • Causes: For a patient treating a poisonous substance, for example, an ICD-10 code could describe whether the patient ingested the substance on purpose or was poisoned unintentionally. This could help with claims, including workers' compensation or insurance, in the future.

Types of ICD-10 Codes

There are two types of ICD-10 codes, these include:

  • The United States uses the ICD-10-CM, or International Classification of Diseases, 10th Revision, Clinical Modification, for diagnosis in all healthcare facilities.
  • The ICD-10-PCS, or Classification of Diseases, 10th Revision, Procedure Coding System, is for procedures in hospitals only.

Uses for ICD-10 Codes

ICD-10 codes are used for:

  • Creating and tracking patient treatment plans
  • Labeling death certificates
  • Monitoring patient safety
  • Medical billing, insurance reimbursements, and collections
  • Collecting data for monitoring public health
  • Health research
  • Understanding less common diseases by detailing their symptoms and how they connect to more well-known conditions

For the general public, ICD-10 codes can help with:

  • Keeping track of healthcare expenses
  • Preventing fraud and overcharges within medical billing
  • Communicating with billing and insurance companies
  • Understanding personal diagnoses and health conditions

ICD-10 Codes for Medical Billing and Insurance

ICD-10 codes are most well known for their use in medical billing for health care facilities and insurance companies. These codes can help all those involved within a medical care transaction keep track of charges while preventing fraud.

How to Find an ICD-10 Code for a Health Condition

There are a couple of ways to find an ICD-10 code. These include:

ICD-10 Codes for Public Health

For public health, the ICD-10 codes provide:

  • An efficient way to collect health care data on large populations of people
  • A way to track rare diseases and provide roadmaps to other conditions they could be related to
  • Diagnostic criteria based on collections of data
  • Information on where disease intervention is needed
  • Data on the social conditions or events that encourage a particular disease

Summary

ICD-10 codes are a part of an international labeling system for health conditions or diseases. The system was adopted by the World Health Organization (WHO) in 1948, and it is used worldwide to categorize and label diseases in an organized manner that encourages efficiency and monitoring of public health.

A Word From Verywell

It can be tough to navigate the complications of most healthcare procedures while monitoring charges and billing. ICD-10 codes help by organizing the diagnoses, causes, and conditions of a disease in an efficient, orderly manner.

ICD-10 codes can help you to work with your own healthcare providers to understand your condition, to navigate treatment, and to keep track of costs.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. World Health Organization. International Statistical Classification of Diseases and related health problems (ICD).

  2. Centers for Medicare & Medicaid Services. Basic introduction to ICD-10-CM.

  3. World Health Organization. ICD-10 Version: 2019.

  4. AAPC. What is ICD-10?

  5. Centers for Disease Control and Prevention. International Classification of Diseases, (ICD-10-CM/PCS) transition - background.