Laboratory Testing for New-Onset Headache in a 70-Year-Old
For a 70-year-old with new-onset headaches and no other symptoms, you should order: erythrocyte sedimentation rate (ESR), complete blood count (CBC), basic metabolic panel (including glucose and sodium), and strongly consider temporal artery biopsy if ESR is elevated or clinical suspicion for giant cell arteritis exists.
Age-Specific Risk Considerations
The patient's age of 70 years is itself a critical red flag that substantially elevates the risk of serious secondary pathology:
- New-onset headache after age 50 is a recognized red flag that increases the likelihood of significant intracranial pathology and warrants thorough investigation 1, 2
- Elderly patients with new-onset headache are approximately 12 times more likely to have serious underlying causes compared to younger adults, including stroke, temporal arteritis, neoplasm, and subdural hematoma 3
- Up to 15% of patients aged 65 and over presenting with new-onset headaches may have serious pathology such as stroke, temporal arteritis, neoplasm, or subdural hematoma 4
Essential Laboratory Tests
Primary Laboratory Panel
ESR (Erythrocyte Sedimentation Rate): This is the single most critical laboratory test in this age group to screen for giant cell arteritis (temporal arteritis), which affects 60-90% of patients with headache as the most common symptom 4
- However, be aware that ESR can be normal in 10-36% of patients with confirmed temporal arteritis, so clinical suspicion should guide further workup even with normal results 4
Complete Blood Count (CBC): To evaluate for infection, malignancy, or hematologic disorders that may present with headache 5
Basic Metabolic Panel including:
Additional Considerations Based on Clinical Context
C-reactive protein (CRP): Can supplement ESR in evaluating for temporal arteritis, as it may be elevated when ESR is falsely normal 4
Thyroid function tests: Thyroid disorders can present with headache and are common in elderly populations 5
Critical Diagnostic Pathway
Temporal Arteritis Evaluation
Given the patient's age, temporal arteritis must be actively excluded:
- If ESR is elevated or clinical suspicion exists (scalp tenderness, jaw claudication, visual symptoms, temporal artery abnormalities), proceed immediately to superficial temporal artery biopsy 4
- Note that temporal artery biopsy can yield false-negative results in 5-44% of cases due to skip lesions, so bilateral biopsy may be considered 4
- Do not delay treatment if clinical suspicion is high, as visual loss from temporal arteritis can be permanent
Neuroimaging Priority
While the question asks about laboratory tests, it's essential to note that neuroimaging takes precedence over laboratory testing in this clinical scenario:
- The American College of Radiology recommends neuroimaging for new-onset headache in older adults as a specific indication 2
- Brain imaging (MRI preferred for non-acute presentations, CT for acute) should be obtained to exclude tumor, stroke, subdural hematoma, or other structural lesions 5, 3
Common Pitfalls to Avoid
- Do not be falsely reassured by a normal ESR: Up to one-third of temporal arteritis cases may have normal ESR 4
- Do not rely solely on laboratory tests: The history and neurologic examination remain paramount, and imaging is typically more revealing than laboratory studies in this age group 1, 5
- Do not delay imaging for laboratory results: If any red flags are present (which age >50 with new headache qualifies as), neuroimaging should proceed concurrently with laboratory evaluation 2, 5
Additional Testing Based on History
If specific features emerge during evaluation:
- Lumbar puncture with CSF analysis: If meningitis, subarachnoid hemorrhage (with negative CT), or carcinomatous meningitis is suspected 5, 6
- Coagulation studies: If anticoagulation use or bleeding disorder is suspected, particularly relevant for subdural hematoma risk 4
- Cancer markers or specific antibody panels: Only if systemic symptoms suggest underlying malignancy or autoimmune disease 5