Bloodwork for OCD
Bloodwork has no role in diagnosing OCD, as the diagnosis is entirely clinical based on structured psychiatric assessment and standardized rating scales. 1, 2
Diagnostic Approach to OCD
OCD diagnosis requires a clinical psychiatric evaluation without laboratory testing. The American Psychiatric Association recommends diagnosing OCD when obsessions and/or compulsions consume more than 1 hour per day AND cause clinically significant distress or functional impairment. 1, 2
Core Clinical Assessment Components
Structured diagnostic interviews are the gold standard, including the Structured Clinical Interview for DSM-5 (SCID-5) or the Anxiety Disorders Interview Schedule for DSM-5 (ADIS-5). 3, 1
Symptom severity quantification using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), with scores ≥14 indicating clinically significant OCD requiring treatment. 1, 2
Mental status examination and detailed psychiatric history form the foundation of assessment, focusing on identifying ego-dystonic obsessions and compulsions. 1
When Bloodwork May Be Indicated
While bloodwork doesn't diagnose OCD, laboratory testing serves to rule out medical conditions that could mimic or contribute to obsessive-compulsive symptoms:
Exclude medical mimics: The diagnosis requires ruling out that symptoms are better explained by substance use or medical conditions before confirming OCD. 1, 2
Pre-treatment screening: Before initiating SSRI therapy (first-line pharmacological treatment), baseline laboratory work may be appropriate per standard medical practice, though this is for medication safety rather than OCD diagnosis. 4, 5
Critical Diagnostic Pitfalls
Don't confuse normal intrusive thoughts with OCD: The key distinguishing features are time consumption (>1 hour/day) and substantial distress or functional impairment, as intrusive thoughts are common in the general population. 1
Differentiate from other psychiatric conditions: Generalized anxiety disorder worries are about real-life concerns and lack compulsive rituals, while depression ruminations are less irrational than OCD obsessions. 2, 6
Document insight level: DSM-5 requires specifying whether the patient has good/fair insight, poor insight, or absent insight/delusional beliefs, as this impacts treatment approach. 1, 2
Essential Documentation
Beyond the clinical diagnosis, document:
Comorbid conditions such as depression, anxiety disorders, and tic disorders, which commonly co-occur with OCD. 1, 2
Family accommodation patterns: Assess whether family members provide reassurance, assist with avoidance behaviors, or participate in rituals, as this maintains symptoms. 3, 2
Functional impairment: OCD causes quality of life impairment comparable to schizophrenia, with significant dysfunction across work, family, and social domains. 1