From the Guidelines
A comprehensive laboratory workup for dizziness should include complete blood count (CBC), comprehensive metabolic panel (CMP), thyroid function tests (TSH, free T4), hemoglobin A1c, vitamin B12 and folate levels, and lipid profile, as these tests help identify common causes of dizziness such as anemia, electrolyte imbalances, thyroid dysfunction, diabetes, vitamin deficiencies, and cardiovascular risk factors.
Key Laboratory Tests
- Complete blood count (CBC) to rule out anemia
- Comprehensive metabolic panel (CMP) to evaluate electrolyte imbalances and renal function
- Thyroid function tests (TSH, free T4) to assess thyroid dysfunction
- Hemoglobin A1c to diagnose diabetes
- Vitamin B12 and folate levels to identify vitamin deficiencies
- Lipid profile to assess cardiovascular risk factors
Additional Specialized Tests
Additional specialized tests may include:
- Vestibular function tests (VNG/ENG) to evaluate vestibular function
- Audiometry to assess hearing loss
- Brain imaging (MRI) to rule out central nervous system pathology
- Electrocardiogram (ECG) to evaluate cardiac function
Clinical Considerations
For patients with acute severe dizziness, consider cardiac enzymes and D-dimer to rule out cardiac events or thromboembolism 1. Testing should be tailored to the patient's presentation, with particular attention to medication review as many drugs can cause dizziness as a side effect. Laboratory testing is most valuable when guided by a thorough history and physical examination, as dizziness can result from multiple organ systems including vestibular, neurological, cardiovascular, metabolic, and psychological causes.
Evidence-Based Recommendations
The American Academy of Otolaryngology-Head and Neck Surgery recommends against routine vestibular function testing or electrocochleography (ECochG) for patients with suspected Meniere's disease, as these tests have limited diagnostic accuracy and may lead to unnecessary delays in diagnosis and treatment 1. Similarly, the American College of Radiology recommends against routine imaging for patients with benign paroxysmal positional vertigo (BPPV) unless there are additional signs or symptoms inconsistent with BPPV 1.
From the Research
Labs for Dizziness Workup
- Laboratory testing and imaging are usually not required for dizziness workup, as stated in 2 and 3
- However, some studies suggest that certain lab tests may be helpful in assessing underlying conditions that could be contributing to dizziness, such as:
- It's essential to note that the physical examination, including orthostatic blood pressure measurement, full cardiac and neurologic examination, assessment for nystagmus, and the Dix-Hallpike maneuver, is a crucial part of the dizziness workup 2, 3, 6
- The HINTS (head-impulse, nystagmus, test of skew) examination can also help distinguish peripheral from central etiologies of dizziness 2, 3