Medical Code Guide for Patients

Medical codes are used to describe diagnoses and treatments, determine costs and reimbursements, and relate one disease or drug to another. Although the CPT code system is the most widely used, many other code sets are also in use. The different code sets are necessary because of the broad range of services and operations within the medical industry.

Patients can use medical codes to learn more about their diagnosis, the services their practitioner has provided, to figure out how much their providers were paid, or even to double-check their billing from either their providers or their insurance or payer.

This article discusses medical coding systems, what they are used for, and how you can use them to benefit your own health care.

CPT Medical Codes

Current Procedural Terminology (CPT) codes are developed by the American Medical Association. They describe every type of medical service (e.g., tests, surgeries, evaluations, and other medical procedures) provided to patients. CPT codes are submitted to insurance, Medicare, or other payers for reimbursement purposes.

Patients may be interested in looking at CPT codes to help them understand the services their doctor provided, double-check their bills, or negotiate lower pricing for their healthcare services.

CPT codes are organized into categories:

• Category I codes are the most commonly used. These codes track healthcare provider services and procedures.
• Category II codes are used alongside category I codes to track supplemental information about a patient, such as medical history and test results.
• Category III codes are temporary codes used for experimental or new services and procedures.

What are 5 common CPT codes?

Different practices may use different codes more often than others, but some of the most common include:

• 99213/99214: Office visit/Outpatient Services
• 90791/90792: Psychiatric evaluation
• 81002/81003: Urinalyses
• 85025: Complete blood count
• 90471: Vaccine administration

HCPCS Medical Codes

Healthcare Common Procedure Coding System (HCPCS) codes are used by Medicare and are based on CPT codes. If you use Medicare it may be helpful to learn about these codes. This is especially true if you have used ambulance services or medical devices outside your healthcare provider's office.

There are two levels:

• Level I HCPCS codes mirror CPT codes and are used to identify medical services and procedures.
• Level II HCPCS codes are alphanumeric and identify non-physician services like ambulance rides, wheelchairs, walkers, other durable medical equipment, and other medical services that don’t fit into Level I.

ICD Medical Codes

International Classification of Diseases (ICD) is published by the World Health Organization (WHO). This diagnostic classification system is the international standard for reporting diseases and health conditions. It uses death certificates and hospital records to count deaths, as well as injuries and symptoms.

ICD codes change over time, so they have a number appended to them to show which set of codes is being used. For example, the ICD-9 code set was introduced during the late 1970s. It was replaced by the more detailed ICD-10 code set on October 1, 2015.

ICF Medical Codes

The International Classification of Functioning, Disability, and Health is also known as ICF. ICF is a framework for measuring health and disability related to a health condition. While ICD classifies disease, ICF looks at how functional a person is in their environment.

DRG Medical Codes

The diagnostic-related group (DRG) system categorizes different medical codes. For billing purposes, hospital services are categorized based on a diagnosis, type of treatment, and other criteria.

This means that hospitals are paid a fixed rate for inpatient services corresponding to the DRG assigned to a given patient, regardless of what the real cost of the hospital stay was, or what the hospital bills the insurance company (or Medicare) for.

The assumption is that patients who fit the same profile will need approximately the same care and services. There are about 500 different DRGs. They are updated annually to add new diagnoses or circumstances.

NDC Medical Codes

The National Drug Code (NDC), is a unique, numeric identifier given to medications. The code is present on all nonprescription (OTC) and prescription medication packages and inserts in the US. The NDC is 10-digits divided into three segments:

• The first segment identifies the product labeler (manufacturer, marketer, repackager, or distributor of the product).
• The second segment identifies the product itself (drug-specific strength, dosage form, and formulation).
• The third segment identifies the package size and type.

It should be noted that just because the number is assigned, that does not mean the drug has been approved by the FDA. The FDA publishes a list of NDC codes in the NDC Directory, which is updated daily.

CDT Medical Codes

Code on Dental Procedures and Nomenclature (CDT) codes allow dentists to get into the coding act. It is a set of procedural codes for oral health and related services.

DSM-IV-TR Medical Codes

In an earlier version of the Diagnostic and Statistical Manual of Mental Disorders, (4th Edition, Text Revision) codes are used to diagnose psychiatric illnesses. They are published and maintained by the American Psychiatric Association.

While you may see these codes in existing patient records, the fifth edition of the DSM was published in 2013 and recommends ICD-10 codes for psychiatric conditions. These also change over time, as there was a revision in October​ 2017.

Summary

Medical codes are used by healthcare providers to track patient diagnosis and treatment and to bill insurance companies for medical services. Many different code sets may be used depending on the organization and the services it provides. The CPT system is the most widely used.

As a patient, you can use these codes to help understand more about your care and to make sure you are being correctly billed for services.

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. American Medical Association. CPT (current procedural terminology).
2. American Academy of Professional Coders. What is CPT?
3. American Medical Association. CPT® code 99213: Established patient office visit, 20-29 minutes.
4. Medicare Coverage Database. Billing and coding: Psychiatry and psychology services.
5. American Academy of Professional Coders. CPT® 81002, under urinalysis procedures.
6. American Academy of Professional Coders. CPT® 85025, under hematology and coagulation procedures.
7. Tsai Y, Zhou F, Lindley MC. Insurance reimbursements for routinely recommended adult vaccines in the private sector. Am J Prev Med. 2019;57(2):180-190. doi:10.1016/j.amepre.2019.03.011
8. Centers for Medicare & Medicaid Services. HCPCS - general information.
9. Centers for Medicare and Medicaid Services. ICD-10.
10. World Health Organization. International classification of functioning, disability and health (ICF).
11. MedPac.gov. Hospital acute inpatient services payment system.
12. U.S. Food and Drug Administration. National drug code directory.
13. CDT: Dental Procedure Codes. American Dental Association.
14. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Arlington, VA: American Psychiatric Association.

By Trisha Torrey
Trisha Torrey is a patient empowerment and advocacy consultant. She has written several books about patient advocacy and how to best navigate the healthcare system.

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