In an older adult with frequent falls and dizziness, what laboratory tests and imaging studies should be ordered to evaluate reversible causes?

Laboratory and Imaging Workup for Falls and Dizziness in Older Adults

Order vitamin D, PTH, TSH, creatinine/eGFR, calcium, and testosterone (in men) as your core laboratory panel, and reserve brain MRI for patients with focal neurologic findings or ataxia—CT head has minimal diagnostic yield (<1%) in isolated dizziness. 1

Laboratory Testing Strategy

The most cost-effective laboratory screening approach identifies metabolic contributors in 94% of patients at risk for falls and fractures 1:

Essential Blood Tests

• Vitamin D (25-OH) - deficiency found in 27% of older fallers
• Parathyroid hormone (PTH) - hyperparathyroidism identified in 21.5%
• Thyroid-stimulating hormone (TSH) - screens for thyroid dysfunction
• Creatinine/eGFR - assesses renal function affecting multiple systems
• Calcium - evaluates for metabolic bone disease
• Testosterone in men - identifies hypogonadism contributing to sarcopenia

This targeted panel costs approximately $190 per patient screened and $258 per new diagnosis, with previously undiagnosed disorders identified in 63.5% of older adults with falls 1.

Additional Considerations

While vitamin B-12, folate, and albumin can be tested, they add cost without substantially improving diagnostic yield in the general falls population 1. Consider these selectively if clinical features suggest specific deficiencies (e.g., macrocytic anemia, malnutrition).

Imaging Strategy: When and What to Order

For Isolated Dizziness Without Neurologic Findings

Do not routinely order brain imaging. The diagnostic yield of CT head in isolated dizziness is extremely low (<1%) in emergency department settings 2. Even MRI with diffusion-weighted imaging yields only 4% positive findings in isolated dizziness 2.

Clinical Triage Determines Imaging Need

Use vascular risk factors and focal neurologic examination to stratify patients 3:

• Age, systolic blood pressure, and focal exam findings predict posterior circulation ischemia with 90% accuracy (AUC 0.90)
• A thorough neurologic examination is more valuable than routine imaging
• CT angiography adds no additional diagnostic value beyond clinical assessment in most cases 3

When to Order MRI Brain

MRI is appropriate when 2:

• Acute vestibular syndrome with neurologic deficits - 12% diagnostic yield vs. 4% without deficits
• Chronic cerebellar ataxia - evaluate for structural lesions, atrophy, or inflammatory causes
• Sensory ataxia - MRI cervical/thoracic spine to assess dorsal columns for:
  • Compressive myelopathy
  • B12/copper deficiency myelopathy
  • Tabes dorsalis (neurosyphilis)
• Recurrent vertigo with brainstem symptoms - evaluate for vertebrobasilar insufficiency or demyelination

MRI Protocol Selection

• Without contrast: First-line for most structural evaluations
• With contrast: Add when suspecting inflammatory, infectious, or neoplastic causes 2
• Include diffusion-weighted imaging (DWI): Essential for detecting acute ischemia

Clinical Pitfalls to Avoid

Don't Over-Image

The 2024 ACR guidelines emphasize that nonspecific dizziness accounts for 2.5% of emergency presentations, yet 22% undergo CT and 10% undergo MRI, despite minimal yield 2. Lightheadedness from dehydration, hypotension, vasovagal reactions, or anxiety requires no CNS imaging.

Don't Miss Orthostatic Causes

Persistent orthostatic intolerance, even without documented orthostatic hypotension, warrants evaluation for autonomic dysfunction and neurodegenerative disorders 4. This is a clinical diagnosis requiring orthostatic vital signs, not imaging.

Don't Forget Medication Review

Sedative and antihypertensive medications are frequent, modifiable contributors to falls 5, 6. Review and reduce these before extensive imaging workups.

Don't Overlook BPPV

Benign paroxysmal positional vertigo is highly treatable with physical maneuvers and doesn't require imaging 6. Perform Dix-Hallpike testing clinically 2.

Algorithm for Decision-Making

1. Obtain orthostatic vital signs and perform focused neurologic exam
2. Order core metabolic panel (vitamin D, PTH, TSH, creatinine/eGFR, calcium, testosterone in men) 1
3. Stratify by clinical presentation:
   • Isolated dizziness + normal exam → No imaging needed 2
   • Focal neurologic findings or ataxia → MRI brain ± spine 2, 3
   • Acute vestibular syndrome with deficits → Urgent MRI with DWI 2
   • Orthostatic symptoms → Autonomic testing, not imaging 4

The combination of targeted laboratory testing and selective imaging based on clinical findings identifies reversible causes in the majority of older adults with falls and dizziness, while avoiding unnecessary, low-yield testing.