Patient's Guide to Medical Codes

Making sense of those confusing medical codes

Medical codes are used to describe diagnoses and treatments, determine costs and reimbursements, and relate one disease or drug to another.

Patients can use medical codes to learn more about their diagnosis, learn more about the services their practitioner has provided, 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 page provides a list of medical coding systems, as well as links to more information:

CPT Codes (Current Procedural Terminology)

Doctor. Adam Berry / Stringer / Getty Images

These codes, developed by the American Medical Association, describe every type of service a healthcare provider may provide to a patient. They are used to make a list of those services, then to submit to insurance or Medicare or another payer for reimbursement purposes.

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

HCPCS Codes (Healthcare Common Procedure Coding System)

HCPCS Codes are used by Medicare and are based on CPT Codes.

Patients who use Medicare, especially those who have needed ambulance services or other devices outside of the doctor's office, may want to learn more about HCPCS codes.

ICD Codes (International Classification of Diseases)

ICD Codes, International Classification of Diseases, are maintained in the United States by the CDC, and internationally by the World Health Organization. They are used to describe diagnoses.

ICD codes change over time, so they have a number appended to them to show which set of codes is being used. ICD-9 codes are often found in patient records. American doctors are now migrating to an updated list of ICD-10 codes.

ICD disease codes are found in vital patient records like death certificates or hospital records.

ICF Codes for Disabilities

ICF codes are relatively new. ICF codes refer to the International Classification of Functioning, Disability, and Health and they describe the outcomes of disability — how functional a patient is in his environment. 

DRGs (Diagnosis Related Groups)

DRGs — Diagnosis Related Groups — were developed by Medicare to group hospital services based on a diagnosis, type of treatment, and other criteria for billing purposes.

When a patient is admitted to the hospital, the reimbursement from Medicare is based on the patient's DRG, regardless of what the real cost of the hospital stay was, or what the hospital bills Medicare for.

The assumption is made that patients that 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, for example, swine flu (H1N1) or hospital-acquired conditions

NDC Codes (National Drug Codes)

NDC Codes are found in the National Drug Code Directory.

Since 1972, the FDA has required all prescription or insulin drug manufacturers to identify and report a unique, three-segment number for each of its products. The FDA maintains an updated list of these numbers on its website. It should be noted that just because the number is assigned, that does not mean the drug has been approved by the FDA.

If you are curious about this NDC for a drug you take, you can research it at the FDA website.

CDT Codes (Code on Dental Procedures and Nomenclature)

CDT codes allow dentists to get into the coding act. CDT refers to Code on Dental Procedures and Nomenclature.

DSM-IV-TR Codes for Psychiatric Illnesses

DSM-IV-TR codes are used to diagnose psychiatric illnesses. They are published and maintained by the American Psychiatric Association. DSM-IV-TR stands for Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision.