What is the initial step in evaluating a patient presenting with depressive symptoms to rule out underlying medical conditions?

Medical Rule Out for Depression: Initial Evaluation Steps

When evaluating a patient with depressive symptoms, immediately determine and treat medical or substance-induced causes of depression before attributing symptoms to primary psychiatric illness. 1

Step 1: Assess for Immediate Safety Concerns

Before proceeding with medical workup, evaluate for:

• Risk of harm to self or others - requires immediate emergency psychiatric referral 1
• Severe agitation - warrants urgent evaluation 1
• Psychosis - requires immediate psychiatric consultation 1
• Confusion or delirium - demands immediate medical evaluation 1

If any of these are present, facilitate a safe environment with one-to-one observation and initiate emergency referral before continuing diagnostic workup. 1

Step 2: Rule Out Medical and Substance-Induced Causes

This is the critical first step in the medical rule-out process. Medical conditions and substances must be identified and treated before diagnosing primary depression. 1

Neurological Causes to Evaluate:

• Stroke - particularly important as flat affect from neurological damage can mimic depression 2
• Traumatic brain injury 2
• CNS infections (meningitis, encephalitis) 2
• CNS malignancies 2
• Seizure disorders 2
• Neurodegenerative diseases (Parkinson's, dementia) 2

Metabolic and Endocrine Disturbances:

• Hypoglycemia 2
• Hyponatremia 2
• Hypocalcemia 2
• Thyroid disorders (both hypo- and hyperthyroidism) 2

Substance-Induced Causes:

• Medication side effects - particularly interferon, corticosteroids, beta-blockers 1, 2
• Drug intoxication 2
• Withdrawal states (alcohol, benzodiazepines, opioids) 2

Essential Physical Examination Components:

• Complete neurologic examination - assess for focal deficits, movement disorders, cognitive impairment 2
• Vital signs assessment - abnormal vital signs may indicate delirium or medical illness 2
• Cardiac examination - cardiovascular disease is commonly comorbid with depression 2
• Respiratory examination - hypoxia can present with depressive symptoms 2

Step 3: Distinguish Organic from Psychiatric Presentation

A critical pitfall is mistaking organic flat affect for primary psychiatric depression. 2

Key distinctions to make:

• Post-stroke aprosodic speech appears as flat affect but results from neurological damage, not depression 2
• Fluctuating presentation suggests delirium rather than primary mood disorder 2
• Persistent flat affect in the context of neurological findings indicates organic cause 2

Step 4: Screen for Depression Severity Using PHQ-9

Once medical causes are ruled out or treated, use the PHQ-9 for systematic assessment. 1

Phased Screening Approach:

First: Identify pertinent history and risk factors (prior depression, family history, recent stressors, chronic medical illness). 1

Second: Administer the 2-item PHQ-9 screening questions:

1. Little interest or pleasure in doing things (anhedonia)
2. Feeling down, depressed, or helpless (depressed mood)

If patient scores 0-1 on both items, no further screening needed. 1

Third: If patient scores ≥2 on either item, complete the full PHQ-9 (remaining 7 items covering sleep, energy, appetite, self-view, concentration, psychomotor changes, and self-harm thoughts). 1

PHQ-9 Score Interpretation:

• 1-7: Minimal symptoms, no intervention needed 1
• 8-14: Moderate symptoms, seek consultation for diagnosis determination 1
• 15-19: Moderate to severe symptoms, refer to psychiatry/psychology 1, 3
• 20-27: Severe symptoms, immediate referral required 1

Note: The cutoff of ≥8 (rather than the traditional ≥10) is recommended based on validation studies in medical populations. 1

Step 5: Assess Unrelieved Physical Symptoms

Treat unrelieved medical symptoms (pain, fatigue, nausea) that may be causing or exacerbating depressive symptoms. 1

Many physical symptoms overlap with depression (fatigue, sleep disturbance, appetite changes), making it essential to address treatable medical contributors first. 4, 5

Common Pitfalls to Avoid

• Failing to obtain medical clearance before attributing symptoms to primary psychiatric illness 2
• Overlooking medication-induced depression - particularly with interferon, corticosteroids, or other CNS-active drugs 1
• Missing delirium - fluctuating mental status suggests delirium, not depression 2
• Ignoring flat affect in aphasic patients - language impairment can mask or mimic depression 2
• Underestimating severity - PHQ-9 scores ≥15 represent significant clinical depression requiring professional intervention 3

Special Populations Requiring Tailored Assessment

• Older adults - depression is more difficult to detect and often presents atypically 1
• Patients with cognitive impairment - require modified assessment approaches 1
• Culturally diverse patients - use culturally sensitive assessment tools when possible 1