**Patient Information:**  
Name: Mr Patient  
Age: 13 years  
Gender: Male  
Medical History: Not specified (text appears non-informative)

**Presenting Symptom:**  
Headache

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### 1. Potential Differential Diagnoses

In a 13-year-old male presenting with headache, consider the following common and serious causes:

- **Primary Headache Disorders:**
  - Migraine (with or without aura)
  - Tension-type headache
  - Cluster headache (less common in this age group)

- **Secondary Headache Causes:**
  - Viral or bacterial infection (e.g., sinusitis, upper respiratory tract infection, meningitis)
  - Medication overuse or withdrawal
  - Refractive error (vision problems)
  - Trauma (concussion, subdural/epidural hematoma)
  - Intracranial mass or space-occupying lesion (rare, but important to consider)
  - Hypertension
  - Dental or temporomandibular joint (TMJ) issues
  - Dehydration

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### 2. Recommended Diagnostic Tests

**Initial Evaluation:**
- **Thorough history and physical examination** (including neurological exam)
- **Vital signs** (including blood pressure, temperature)

**Further investigations based on clinical suspicion:**
- **CBC, CRP/ESR** (if infection or inflammation suspected)
- **Urinalysis** (if systemic symptoms)
- **Ophthalmologic evaluation** (if visual symptoms)
- **Neuroimaging (CT/MRI brain):**
  - If red flags present (see below)
  - Abnormal neurological findings
  - Sudden onset ("thunderclap" headache)
  - Headache worsened by Valsalva or position
- **Lumbar puncture:** If meningitis or subarachnoid hemorrhage suspected and imaging is negative

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### 3. Urgency Level

**Medium**  
- Most pediatric headaches are benign, but a careful assessment is required to rule out serious causes.
- If any red flags are present (see below), urgency increases to **High**.

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### 4. Key Observations and Clinical Notes

- **History:** Onset, duration, frequency, location, quality, severity, associated symptoms (nausea, vomiting, photophobia, phonophobia, visual changes, fever, neck stiffness, recent trauma, altered mental status)
- **Family history:** Migraines or neurological disorders
- **Medication use:** Recent changes, overuse
- **Social history:** School stress, sleep patterns, screen time, caffeine use
- **Physical exam:** Full neurological exam, fundoscopic exam (for papilledema), assessment for meningeal signs, sinus tenderness

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### 5. Red Flags to Watch For

- Sudden, severe ("worst ever") headache
- Headache with fever, neck stiffness, photophobia (meningitis/encephalitis)
- Altered mental status, confusion, seizures
- Focal neurological deficits (weakness, vision loss, ataxia)
- Papilledema (suggests increased intracranial pressure)
- Headache worsened by lying down, coughing, or Valsalva
- Recent head trauma
- Persistent vomiting
- Headache awakening from sleep or present on awakening
- Immunosuppression or known malignancy

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**Summary:**  
A 13-year-old male with headache requires a thorough history and physical exam to distinguish between primary and secondary causes. Most headaches in this age group are benign, but red flags must be actively sought. If any are present, urgent evaluation and neuroimaging are warranted. Otherwise, outpatient workup and symptomatic management may be appropriate.

**Recommendation:**  
Further clinical details are needed. Please consult a healthcare professional for a comprehensive evaluation.