Diagnostic criteria refer to a set of standardized signs, symptoms, tests, and other clinical findings that are used by healthcare professionals to diagnose a specific disease or condition. These criteria provide a clear framework for identifying and differentiating one condition from others with similar presentations.

### Key Features of Diagnostic Criteria: 1. Objective and Subjective Findings: They typically include both objective findings (e.g., lab results, imaging) and subjective symptoms (e.g., patient-reported pain). 2. Specificity: Diagnostic criteria are designed to be specific to a particular disease, minimizing the risk of misdiagnosis. 3. Standardization: They ensure consistency in diagnosis across different healthcare providers and settings. 4. Evidence-Based: Developed through research and clinical studies, diagnostic criteria are based on evidence showing which signs and symptoms reliably indicate the condition.

### Example: - DSM-5 Criteria for Major Depressive Disorder: The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) provides specific criteria such as depressed mood, loss of interest, weight changes, sleep disturbances, and more, which must be present for a certain duration to diagnose depression. - McDonald Criteria for Multiple Sclerosis: This set of criteria incorporates MRI findings, clinical symptoms, and cerebrospinal fluid analysis to diagnose multiple sclerosis.

Diagnostic criteria are crucial in guiding healthcare professionals to make accurate and consistent diagnoses.