What ICD-10 Code is for Mental Disorder, Not Other Specified?

Learn About ICD-10 Codes for Unspecified Mental Disorders

When a client sees a physician, they expect to walk out with a diagnosis and know what they should do next. Unfortunately, that’s not always possible. A doctor may not have enough information or see enough symptoms to diagnose someone with a mental disorder. That is why ICD-10 (the version of the International Classification of Diseases used in the United States) designates code F99 for a mental disorder, not other specified.

This code appears in the files of clients who exhibit symptoms of a mental disorder but do not match the requirements for a specific condition. 

We’ll explain more about this code and why you would diagnose a client in this way.

What Is an Unspecified Mental Disorder?

Mental disorders are very common in the United States and other parts of the world. The National Alliance on Mental Illness (NAMI) found that 20% of adults suffer from mental illness every year, and one out of six young people 6-17 does. Some of the common ones you hear about include anxiety and depression. The ICD has codes reserved for those disorders and others that doctors can use based on the client’s symptoms.

The term “unspecified mental disorder” is a category used within the diagnosis. Doctors also use terms like not otherwise specified (NOS) and unspecified disorder. It means the client presented with symptoms that indicate a certain mental disorder but they do not have a specific condition. For example, the individual may have symptoms of a disorder within the depression family but not have depression. It allows the physician to give a general diagnosis but not a specific one.

Depressive Disorders

Depression is one of the most common disorders found in the United States. The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) lists three depressive disorders: major depressive disorder, persistent depressive disorder, and unspecified depressive disorder. A client who has a mental disorder, not specified code in their file when they have some of the symptoms of depression but not enough to fill into one of the categories. It also occurs when the doctor who sees and diagnoses them does not have enough information. This commonly happens in emergency departments. Another physician may change the diagnosis later.

The symptoms of an unspecified depressive disorder are similar to the signs of depression and include:

• Energy loss or fatigue
• Hopeless or sad feelings
• Guilty feelings
• A lack of interest or limited interest in activities they usually enjoy
• Delayed movements
• Gaining or losing weight
• Concentration problems
• Insomnia or sleeping more than they should
• Self-harm or thoughts of suicide

Unspecified Anxiety Disorders

Anxiety disorders cause persistent or frequent anxious thoughts. Physicians often use this diagnosis when they have a client who presents with general anxiety but they do not meet the criteria for one of the specific disorders. The symptoms of anxiety disorders include:

• Fatigue
• Worrying more about certain things, people, or activities
• Concentration problems
• Feeling restless
• Trouble sleeping
• Irritability

Other Unspecified Mental Disorders

There are other disorders that use this same code, such as an unspecified behavior disorder. Behavior disorders change the way a person, often a child, acts. Some of the disorders within this category include:

• Disruptive, impulse control, and conduct disorder
• Oppositional defiant disorder
• Conduct disorder

This family of disorders can cause children to act out or act up. Parents usually notice that their kids refuse to follow orders or requests and that they have problems following rules. Kids may also become annoyed quite easily and take steps to annoy or irritate others. As they get older, they may break laws and steal from others or refuse to attend school. Unspecified behavior disorders often prevent clients from understanding the consequences of their actions.

Unspecified bipolar disorder refers to someone who shows symptoms of bipolar disorder but does not fall into a specific type. They experience both manic and depressive episodes. Some of the signs of a manic episode include euphoric feelings, feeling jumpy or hyper, talking quickly, racing thoughts, and an inability to sleep. The client will also experience hopeless and/or suicidal thoughts, concentration issues, trouble sleeping or sleeping too much, and weight or diet changes, which are some of the common symptoms of depression. Someone diagnosed with bipolar disorder will often have both manic and depressive episodes that go along with mood swings.

The DSM-5 also includes an unspecified form of obsessive-compulsive and related disorder. Often called OCD, the disorder causes intrusive thoughts. The client may feel like they need to wash their hands multiple times or check the door lock several times before they leave the house. If they do not complete their rituals, they think something bad will happen to them or someone they know.

Body dysmorphia falls within this category. It affects the way a client feels about their body and can lead to them taking drastic measurements to change the way they look. Body dysmorphia with flaws is a condition that occurs when someone can observe the changes in the individual’s body. It can occur with or without repetitive behaviors, too. Chewing the inside of the mouth or chewing the nails are examples of repetitive behaviors. Similar conditions and symptoms can go along with the disorder, such as jealousy of their loved ones and fear that certain activities will lead to deformities.

Unspecified vs. Standard Diagnoses

An unspecified mental disorder is not necessarily less severe than a standard disorder. They include the same symptoms but indicate that the physician made a general diagnosis that can change later. Clients usually present with a combination of general symptoms that go along with a specific disorder but require more care than they can get at the moment. From 2019 to 2023, the number of emergency room visits among teens increased among those seeking help for their mental health. More young women than young men sought help.

ICD-10 Codes for Unspecified Mental Disorders

Physicians used ICD-9 codes up through 20102 when the World Health Organization (WHO) implemented the ICD-10. WHO uses these codes for several things:

• As a way to accurately report the cause of death of a client
• To help maintain client data in different regions
• To create a consistent way of keeping records
• To provide universal health care across hospitals and facilities

What Is the ICD-10 Code?

The ICD-10 code for a mental disorder, not other specified, is F99. It serves as a billing code and applies to mental disorders that are due to some type of unknown condition. It can also apply to pregnant women who exhibit the symptoms of a mental disorder and women who show signs after they give birth. The codes that come before this one are for other disorders that you may diagnose a client with later after you perform a thorough examination.

Reasons to Use an Unspecified Diagnosis Code

Working in an emergency room means you see multiple clients every shift. Many hospitals have physician assistants and nurses along with other workers who see clients before you do. You may spend a few minutes with the person or a few hours before you release or admit them. Adults and children can both receive an unspecified diagnosis code. It essentially means you know they had certain symptoms, but you didn’t know how to treat them. If you cannot perform a complete evaluation, you can enter the code and let the next physician know they need to take a deeper look.

Using the ICD-10 code is also common when the doctor needs more information. For example, you might have a teen who shows some signs of depression but you’re not sure if they have a depressive disorder or they’re simply acting like a teenager. As one of the first doctors to see the client, you need to become more familiar with them and their symptoms before you diagnose them. It’s also likely that you want to see how their symptoms develop and weed out any underlying conditions first. You may want to consider environmental factors that affect them, too. Though you do not need to know how to code or even how coding works, you must know the ICD-10 code to use for a client with an unspecified mental disorder.

One reason you need to know the F99 code is to bill a client’s insurer. Insurance companies cover the health care needs of an individual. They make their co-pay when they see you. You then bill the insurer and get the money you spent on their care reimbursed. Using the wrong code can result in many problems and keep you from getting your payment. The insurer will require that you use the correct code to identify the client and any care you provide. While the billing and coding department in your facility can add the code for you, you may need to do it yourself. Rural facilities and smaller hospitals still require that doctors enter the right codes.

WHO uses ICD-10 codes to track records and share data. This allows the organization to see where clusters of clients received the same diagnosis, which it can use to look for environmental and other factors that led to the condition. All of the information you share in your records will help WHO manage its records and keep accurate data.

If you work in a large facility, your files will go to the billing and coding department. The coder will go through the file, enter the data into the system, and send the information to the biller who is then responsible for billing the insurer on file. Coders do not have medical training and may have a difficult time deciphering the record due to poor handwriting or other problems. When you add the right code, the coder can quickly input the data and send it to the biller. This ensures the biller has all of the information they need to create a bill for the provided services.

A good way to see why you need to use the correct ICD-10 code is to look at the benefits of the codes, which include:

• They improve the treatments and services clients need.
• You prevent errors within the system.
• The codes help you keep track of multiple treatments a client requires.
• You help research teams keep track of new and emerging data.

The last benefit is especially helpful as times change. When WHO introduced the ICD-10 codes, it selected 140,000 codes. The previous version had only 17,000 codes. Many of the changes correlate to changes in the DSM-5, which applies to all mental disorders.

One of the biggest changes from the DSM-4 to the DSM-5 is that it replaced the term “not otherwise specified” with “not other specified.” The new term now applies to specific conditions rather than a combination of symptoms. For example, someone who presents with signs of depression can receive a depressive disorder not other specified diagnosis. They can then talk to a psychologist or psychiatrist and begin their treatment without going through further testing, though the doctor may do more testing to diagnose the client with a certain type of depression. Other unspecified disorders include feeding, eating, and tic disorders.

Edit and Track Notes Easily

As someone who works with clients who have mental disorders, you know the issues associated with keeping track of notes. AutoNotes is an app designed to make your professional life a little easier. Once you download the app, you pick the best template for your services. Fill out the form with information about your appointment and client. You then finalize the document and download a copy for your records. Our templates only require a few lines and will then summarize the data. You can even choose from free and premium plans. 

Try AutoNotes today to see how quickly you can record ICD-10 codes and write detailed records to better manage your caseload.