Key terms on this page (6)
- Psychopathology
- The study of mental disorders: their signs, course, causes and how they are classified.
- DSM-5-TR
- The Diagnostic and Statistical Manual of Mental Disorders, fifth edition, text revision (2022), from the American Psychiatric Association.
- ICD-10-CM
- The US clinical modification of the WHO’s International Classification of Diseases. Its codes are required on health insurance claims.
- Specifier
- An added detail, such as severity or course, that narrows a diagnosis and can change its code.
- Differential diagnosis
- Weighing the conditions that could explain the same symptoms, and ruling them in or out.
- Z code
- An ICD-10-CM code for a condition that may be a focus of care but is not a mental disorder, such as relationship distress.
What a diagnosis is for
Diagnosis gets a mixed reception in therapy training. Some students arrive wary of labels; others expect it to be the center of the work. In practice it is a shared language. It helps you choose treatments with evidence behind them, talk with a psychiatrist or a school, track whether things are improving, and, very concretely, get paid by insurance.
It is also a judgment about a person, and it can follow them. Good clinicians hold diagnoses lightly, explain them to clients in plain words, and change them when the picture changes.
How the DSM-5-TR is built
The DSM-5 dropped the old five-axis system in 2013, and the 2022 text revision kept the same three-part shape. Most of your time will be spent in Section II.
- Section I
- The basics
How to use the manual, the definition of a mental disorder, and a caution about using it in court.
- Section II
- Criteria and codes
About twenty chapters of disorders, ordered roughly across the lifespan: neurodevelopmental first, neurocognitive near the end. Each entry has criteria, specifiers, codes and text on prevalence, course, culture and differential diagnosis.
- Section III
- Emerging measures
Assessment measures, the Cultural Formulation Interview, an alternative model for personality disorders, and conditions needing more research.
At the end of Section II is a chapter many students skip and practicing clinicians use daily: other conditions that may be a focus of clinical attention. These are the Z codes, for things like relationship distress, housing problems or uncomplicated bereavement, which matter in therapy without being disorders.
Reading a diagnosis line
A diagnosis in a chart or on a claim has three parts. Learning to read them now saves confusion later, when you are writing treatment plans and billing.
A diagnosis line reads: F33.1, major depressive disorder, recurrent episode, moderate. It has three parts: the ICD-10-CM code, the DSM-5-TR diagnosis name, and the specifiers.
- ICD-10-CM code
- F33.1What goes on the claim. “F” is the mental and behavioral chapter; insurers read the code, not the words.
- DSM-5-TR diagnosis
- Major depressive disorderThe name and criteria set from the DSM. The DSM lists the matching ICD-10-CM code for each diagnosis.
- Specifiers
- recurrent episode, moderateDetails that sharpen the picture. Here they also change the code: a single moderate episode is F32.1.
Codes you will see often
- F41.1Generalized anxiety disorder
- F43.10Posttraumatic stress disorder
- F43.22Adjustment disorder with anxiety
- F43.81Prolonged grief disorder
- F90.2ADHD, combined presentation
- Z63.0Relationship distress with spouse or intimate partner (not a disorder)
Differential diagnosis, step by step
Many diagnostic mistakes come from stopping at the first diagnosis that fits. Differential diagnosis is the habit of asking what else could explain the same picture, in an order that catches the dangerous and the easily missed first. Walk through one invented case:
The case (invented)
A 38-year-old man, laid off two months ago, says he has felt flat and slept badly for six weeks. His partner made the appointment.
Step 1 of 6 · Rule out malingering and factitious disorder.
Is anyone exaggerating or inventing symptoms?
Rare, but checked first because everything else assumes the report is genuine. An obvious outside gain (a court case, a disability claim) is the usual prompt.
In this case
No outside gain, and his partner describes the same changes. Move on.
Diagnosis and billing
Since 1 October 2015, HIPAA has required ICD-10 codes on health insurance claims, so every claim you submit carries at least one ICD-10-CM diagnosis code. Insurers pay for treatment that is medically necessary for a diagnosed condition, and your notes have to show that link. You will learn how in documentation and notes.
Two practical points. Codes change every 1 October, as when prolonged grief disorder got its own code, F43.81, in 2022, so code from the current list. And many insurers will not pay a claim whose only diagnosis is a Z code, which creates pressure to diagnose. Choosing a more serious diagnosis than the evidence supports, to get paid, is an ethics violation and can be insurance fraud. If a client doesn’t meet criteria for a disorder, say so, and discuss paying privately.
How it shows up on the exams
How to get ahead
- Learn the major chapters cold: depressive, bipolar, anxiety, trauma- and stressor-related, obsessive-compulsive, substance-related, neurodevelopmental and personality disorders cover most of what you will see.
- Read the differential section at the end of each disorder, not just the criteria. That is where exam questions come from.
- Make comparison cards for look-alikes: major depression vs persistent depressive disorder, PTSD vs acute stress disorder vs adjustment disorder, bipolar I vs II.
- Practice with case books. The APA publishes DSM-5-TR clinical cases, and working through them trains the judgment that criteria lists don’t.
Myths worth dropping
Myth
“A diagnosis describes who someone is.”
Actually
It describes a pattern a person is experiencing now. Say “a person with depression,” and keep it revisable.
Myth
“If they meet the criteria, the diagnosis is done.”
Actually
You still rule out substances, medical causes and better-fitting disorders, and check for real impairment.
Myth
“Insurers need the most serious diagnosis.”
Actually
They need an accurate one, supported in the notes. Inflating a diagnosis is fraud, not kindness.
Next · Step 8
Theories of therapy and the evidence
Once you can name what a client is facing, the next question is what to do about it: the families of therapy, and what decades of research say actually helps.
Questions people ask
Can LMFTs, counselors and social workers diagnose?
In most states, yes, once licensed, and associates usually diagnose under their supervisor. Scope of practice is set by each state’s law, so the exact wording varies. Check your state board’s scope-of-practice rules.
What is the difference between the DSM and ICD-10-CM?
The DSM-5-TR, from the American Psychiatric Association, holds the criteria and descriptions clinicians use to make a diagnosis. ICD-10-CM is the US version of the World Health Organization’s classification, and it supplies the codes that HIPAA requires on insurance claims. The DSM lists the ICD-10-CM code for each of its diagnoses.
Is the DSM-5-TR the current edition?
Yes. The DSM-5-TR (text revision) was published in March 2022. It kept the DSM-5 structure, revised the text of most disorders, added prolonged grief disorder, and updated codes. The APA also publishes coding updates as ICD-10-CM changes each October.
Should I buy the full DSM-5-TR as a student?
Many programs require it, and you will use it for years. The smaller desk reference holds the criteria without the text; the full manual is worth having for the descriptions, differential sections and cultural material.
Does the US use ICD-11?
Not for billing yet. ICD-11 is in use internationally, but US claims still use ICD-10-CM, updated every 1 October.
Sources
Checked 28 October 2026. Codes change every October; check the current ICD-10-CM list before you bill.
- American Psychiatric Association, DSM-5-TR — The current manual (published March 2022), its structure, and its coding updates.
- CMS, ICD-10 — ICD-10 required for all HIPAA-covered entities since 1 October 2015; code sets update every 1 October (FY 2027 files current).
- NBCC, Release of the DSM-5-TR — Summary of DSM-5-TR changes, including prolonged grief disorder.
- First, DSM-5-TR Handbook of Differential Diagnosis (APA Publishing) — The six-step approach to differential diagnosis that the walk-through is adapted from.
- ASPPB, EPPP content areas — Assessment and diagnosis is 16% of EPPP Part 1.
- NBCC, National Counselor Examination — Intake, assessment and diagnosis domain in the NCE content outline.
- AMFTRB, the national MFT examination — Domain on assessing, hypothesizing and diagnosing.
- ASWB, 2026 exam blueprints and Examination Guidebook — Assessment and Planning is 32% of the Clinical exam (blueprints in use since 3 August 2026), including use of the DSM in assessment.