What lab workup should be done for an elderly patient with dementia and increasing agitation?

Laboratory Workup for Elderly Dementia Patient with Increasing Agitation

The priority is to identify and treat reversible causes of delirium superimposed on dementia, which requires a comprehensive metabolic and infectious workup including CBC with differential, complete metabolic panel, TSH, vitamin B12, urinalysis, and chest X-ray if infection is suspected. 1, 2

Critical First Step: Distinguish Delirium from Dementia Progression

The acute change in agitation suggests delirium superimposed on baseline dementia, which has significant implications for mortality and morbidity. 1 Delirium is characterized by acute onset and fluctuating course, while dementia has insidious onset and constant progression. 1

Essential Laboratory Tests

Core Metabolic Panel

• Complete Blood Count (CBC) with differential to identify infection, anemia, or hematologic abnormalities that contribute to agitation 1, 2
• Complete Metabolic Panel including:
  • Electrolytes (sodium, potassium, chloride, bicarbonate) to detect hyponatremia and other imbalances 2
  • BUN and creatinine for uremia assessment 2
  • Glucose for hypo/hyperglycemia 2
  • Calcium for hypercalcemia from hyperparathyroidism 2
  • Liver function tests (AST, ALT, alkaline phosphatase, bilirubin) 2

Endocrine and Vitamin Assessment

• Thyroid-stimulating hormone (TSH) as hypothyroidism is a common reversible cause 1, 2
• Vitamin B12 levels as deficiency can mimic or exacerbate dementia symptoms 1, 2
• Folate levels alongside B12 1, 2

Inflammatory Markers

• C-reactive protein (CRP) to evaluate systemic inflammation 2
• Erythrocyte sedimentation rate (ESR) as additional inflammatory marker 2
• Homocysteine as elevated levels may contribute to vascular cognitive impairment 2

Infection Screening

• Urinalysis is critical as urinary tract infections are the most common cause of delirium in elderly dementia patients 1
• Chest X-ray if pneumonia is suspected, as it is the second most common infectious cause 1

Additional Testing Based on Clinical Context

Medication Review

Obtain measurable medication levels if the patient is on medications with narrow therapeutic windows (digoxin, anticonvulsants, lithium). 1 Pay special attention to anticholinergic medications, which commonly precipitate delirium. 1

Cardiac Evaluation

EKG should be obtained to evaluate for arrhythmias or cardiac ischemia contributing to altered mental status. 1

Selective Testing (Not Routine)

• Syphilis serology (RPR/VDRL) only with clinical suspicion 1, 2
• HIV testing only in patients with risk factors 2
• Heavy metal screening only with specific exposure history 1, 2

Common Pitfalls to Avoid

Do not assume behavioral changes are simply dementia progression without ruling out delirium. The consequences of missing delirium include increased mortality, extended hospital stays, and permanent functional decline. 1

Do not overlook pain as a precipitant. Inadequate pain control is a common reversible cause of agitation in dementia patients. 1

Do not forget to assess for dehydration and electrolyte disturbances, which should be promptly treated. 1

Clinical Integration

The laboratory workup must be integrated with medication review (especially anticholinergics, sedatives, antipsychotics, vasodilators, and diuretics), orthostatic blood pressure assessment, and evaluation for constipation/urinary retention. 1 This comprehensive approach identifies the multiple potential contributors to acute agitation in elderly dementia patients, allowing targeted treatment of reversible factors that impact morbidity and mortality.