Laboratory Testing for Ongoing Dizziness in Patients Over 50
Routine laboratory testing is not indicated for isolated dizziness in patients over 50 with normal vital signs and a non-contributory examination. 1
When Laboratory Testing is NOT Needed
Laboratory panels have very low diagnostic yield in patients with dizziness who have returned to baseline neurologic status and should generally be avoided. 2 The evaluation of dizziness should focus on timing, triggers, and physical examination findings rather than reflexive laboratory ordering. 1, 3
Selective Laboratory Testing Based on Clinical Context
Immediate fingerstick glucose is the single most important test to perform, as hypoglycemia is the most frequently identified unexpected abnormality in dizzy patients. 2, 3
Order targeted labs only when specific clinical features suggest:
Electrolyte panel (basic metabolic panel): Only if history or examination reveals vomiting, diarrhea, dehydration, or other signs suggesting electrolyte disturbances 1, 2
Thyroid function tests: Consider when affective symptoms (depression, anxiety) accompany dizziness, suggesting possible thyroid disease 1
Complete blood count: Not routinely indicated unless anemia is suspected based on examination findings 4, 5
The Evidence Against Routine Laboratory Panels
Comprehensive laboratory panels rarely change management in isolated dizziness and should be avoided. 2 The diagnostic approach should instead prioritize:
Categorizing by timing: Seconds suggests BPPV, hours suggests Ménière's or vestibular migraine, days to weeks suggests vestibular neuritis or stroke 1, 3
Identifying triggers: Head position changes (BPPV), spontaneous onset (vestibular neuritis/stroke), standing (orthostatic hypotension) 1, 3
Performing targeted physical examination: Dix-Hallpike maneuver for positional symptoms, HINTS examination for acute persistent vertigo, complete neurologic examination 1, 3
Critical Pitfall to Avoid
Do not order routine laboratory panels as a substitute for proper clinical evaluation. The vast majority of dizziness diagnoses are made through history (timing and triggers) and physical examination (Dix-Hallpike, HINTS, neurologic exam), not laboratory testing. 1, 2, 3 Ordering comprehensive labs delays appropriate diagnosis and treatment while adding unnecessary cost. 2
High-Risk Features Requiring Urgent Evaluation (Not Labs)
For patients over 50 with vascular risk factors (hypertension, diabetes, atrial fibrillation, prior stroke), the priority is MRI brain without contrast, not laboratory testing, as 11-25% may have posterior circulation stroke even with normal neurologic examination. 2, 3 Other red flags requiring imaging rather than labs include focal neurologic deficits, sudden hearing loss, inability to stand or walk, and new severe headache. 1, 2