Testing for anxiety and depression involves a combination of questionnaire-based screening tools, a clinical interview with a mental health professional, and sometimes blood work to rule out physical causes. There is no single lab test that can diagnose either condition. Instead, diagnosis relies on a structured conversation about your symptoms, how long they’ve lasted, and how much they interfere with your daily life.
Self-Screening Questionnaires
The most common starting point is a short, standardized questionnaire. These are often handed out in a primary care office before you even see the doctor, and many are freely available online. They don’t provide a diagnosis on their own, but they give you and your provider a measurable snapshot of where your symptoms fall.
For depression, the most widely used tool is the PHQ-9 (Patient Health Questionnaire-9). It asks nine questions about the past two weeks, covering things like sleep changes, energy levels, appetite, concentration, and feelings of worthlessness. Each answer is scored from 0 to 3, and your total falls into one of five ranges:
- 0 to 4: Minimal or no depression
- 5 to 9: Mild depression
- 10 to 14: Moderate depression
- 15 to 19: Moderately severe depression
- 20 to 27: Severe depression
A score of 10 or above typically prompts a provider to explore further. Another common depression screener, the Beck Depression Inventory (BDI-II), uses a slightly different scale: 0 to 13 indicates no depression, 14 to 19 mild, 20 to 28 moderate, and 29 to 63 severe.
For anxiety, the standard tool is the GAD-7 (Generalized Anxiety Disorder-7). It works the same way: seven questions scored 0 to 3, with cutoffs at 5 for mild anxiety, 10 for moderate, and 15 or above for severe. If you’ve ever filled out a form at your doctor’s office asking how often you’ve felt nervous, unable to stop worrying, or restless over the past two weeks, you’ve likely completed one of these.
These questionnaires are useful precisely because they’re simple. But they have limitations. A screening tool can flag that something is going on; it can’t tell you exactly what. Scores can be influenced by a bad week, a stressful event, or even a physical illness. That’s why a high score leads to the next step: a clinical evaluation.
What Happens During a Clinical Evaluation
A formal diagnosis comes from a structured conversation with a qualified professional. Psychiatrists, psychologists, and psychiatric nurse practitioners are all trained to diagnose anxiety and depression. Your primary care doctor can also make a diagnosis, though they may refer you to a specialist for complex cases.
The evaluation typically starts with open-ended questions. You’ll be asked about your main concerns, when your symptoms started, whether they’ve gotten better or worse over time, and what your daily life looks like. The clinician will also ask about your personal history: childhood experiences, relationships, work or school stress, substance use, past mental health treatment, and family history of psychiatric conditions. This isn’t small talk. Family history of depression, for instance, significantly increases your own risk, and past trauma shapes how anxiety presents.
During this conversation, the clinician is also conducting what’s called a mental status exam. This isn’t a separate test you sit down for. It’s an ongoing observation of your mood, speech patterns, thought process, energy level, and general presentation. They’re noting whether your emotions match what you’re describing, whether your thoughts seem organized, and whether you mention anything that suggests risk of self-harm.
The whole process usually takes 45 minutes to an hour for an initial appointment. Some providers spread the evaluation across two sessions.
Diagnostic Criteria Your Provider Uses
Behind the scenes, your clinician is matching your symptoms against specific criteria from the DSM-5-TR, the standard diagnostic manual used in mental health care. Knowing what these criteria look like can help you understand what your provider is listening for.
For major depression, the threshold is five or more symptoms present during the same two-week period, and at least one of those symptoms must be either persistent depressed mood or a noticeable loss of interest or pleasure in activities you used to enjoy. The other possible symptoms include significant weight or appetite changes, insomnia or sleeping too much, physical restlessness or feeling slowed down, fatigue, feelings of worthlessness or excessive guilt, difficulty concentrating or making decisions, and recurrent thoughts of death or suicide.
For generalized anxiety disorder, the core requirement is excessive worry occurring more days than not for at least six months, about multiple areas of life (not just one specific thing). That worry must be accompanied by three or more of these six symptoms: restlessness or feeling on edge, being easily tired, difficulty concentrating, irritability, muscle tension, and sleep problems.
The duration matters. Feeling depressed for a few days after a breakup doesn’t meet the two-week threshold. Worrying intensely during finals week doesn’t meet the six-month threshold. These criteria exist to distinguish clinical conditions from normal emotional responses to life events.
Blood Tests That Rule Out Physical Causes
No blood test can diagnose depression or anxiety directly. But several physical conditions produce symptoms that look nearly identical, so your provider may order lab work to rule them out before settling on a mental health diagnosis.
Thyroid testing is the most common. Both an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism) can cause psychiatric symptoms ranging from mild depression and anxiety to severe mood disturbances. Some researchers have proposed that localized thyroid hormone imbalances in the brain can trigger depression even when blood levels of thyroid hormone appear normal, which is one reason thyroid issues are easy to miss.
Vitamin D levels are another frequent check. Vitamin D plays a protective role in the brain by supporting the growth and survival of neurons, regulating inflammation, and influencing the production of key signaling chemicals involved in mood. Low vitamin D is common, especially in northern climates or people who spend most of their time indoors, and it’s associated with both depression and anxiety symptoms. Interestingly, thyroid disorders themselves can lower vitamin D levels by impairing absorption and activation, so these two issues sometimes overlap.
Your provider may also check for anemia through a complete blood count, since low iron causes fatigue, difficulty concentrating, and irritability that closely mimics depression. Blood sugar levels, liver and kidney function, and certain nutritional deficiencies (particularly B12 and folate) are other common tests depending on your symptoms.
If any of these come back abnormal, treating the underlying physical condition often improves or resolves the mood symptoms. If they come back normal, that helps confirm the diagnosis is a primary mood or anxiety disorder.
Where to Get Tested
The easiest entry point for most people is a primary care appointment. Tell your doctor you’ve been struggling with your mood or persistent worry, and they can administer a screening questionnaire, order relevant blood work, and either make a diagnosis themselves or refer you to a specialist.
If you want to go directly to a mental health professional, three types of providers are qualified to give a formal diagnosis. Psychiatrists are medical doctors who completed additional training in mental health; they can diagnose and prescribe medication. Psychologists hold doctoral degrees and can diagnose and provide therapy, though in most states they cannot prescribe medication. Psychiatric nurse practitioners can assess, diagnose, prescribe, and provide therapy.
Many people start with an online screening tool at home, and that’s a reasonable first step. If your PHQ-9 score lands at 10 or above, or your GAD-7 score reaches 10 or higher, that’s a strong signal to schedule an appointment. Even scores in the mild range (5 to 9 on either scale) are worth discussing with a provider if the symptoms are affecting your work, sleep, or relationships. The screening gives you language for the conversation and helps your provider understand the severity from the start.