From the Guidelines
Blood tests for delirium screening should include a complete blood count, comprehensive metabolic panel, thyroid function tests, vitamin B12 and folate levels, urinalysis, and inflammatory markers like C-reactive protein. These tests help identify common causes of delirium such as infections, electrolyte imbalances, organ dysfunction, and nutritional deficiencies. Specifically, check for abnormal sodium, calcium, glucose, and kidney function values, as these frequently contribute to altered mental status 1. Blood cultures should be obtained if infection is suspected. Drug levels and toxicology screens are important when medication toxicity or substance use may be contributing factors. Arterial blood gases may be necessary if hypoxemia or acid-base disturbances are suspected. These laboratory investigations should be performed promptly when delirium is suspected, as early identification of underlying causes allows for targeted treatment and potentially faster resolution of symptoms.
Key Laboratory Tests
- Complete blood count to identify anemia, infection, or other hematological abnormalities
- Comprehensive metabolic panel to assess electrolyte imbalances, kidney function, and glucose levels
- Thyroid function tests to evaluate for thyroid dysfunction
- Vitamin B12 and folate levels to identify nutritional deficiencies
- Urinalysis to detect urinary tract infections or other renal abnormalities
- Inflammatory markers like C-reactive protein to identify underlying inflammation or infection
Additional Considerations
- Drug levels and toxicology screens to assess for medication toxicity or substance use
- Arterial blood gases to evaluate for hypoxemia or acid-base disturbances
- Blood cultures if infection is suspected
- Neuroimaging may be necessary in some cases to rule out other causes of altered mental status
Remember that blood tests are just one component of a comprehensive delirium workup, which should also include thorough history, physical examination, and often neuroimaging 1. The use of standardized assessment tools like the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) or the Intensive Care Delirium Screening Checklist (ICDSC) can aid in the diagnosis of delirium 1.
From the Research
Blood Tests for Delirium Screening
There are no specific blood tests mentioned in the provided studies as a requirement for screening for delirium.
Diagnostic Approach
- The diagnosis of delirium is clinical, based on observed disturbances of consciousness and cognitive dysfunction 2.
- The Confusion Assessment Method (CAM) is a diagnostic tool with high sensitivity and specificity for delirium 2.
- A thorough diagnostic approach should include the identification of predisposing factors and treatment of underlying causes 2, 3.
- Diagnostic testing may include a search for metabolic and infectious derangements, and consideration of magnetic resonance imaging, cerebrospinal fluid analysis, and electroencephalography in select clinical situations 4.
Delirium Etiology and Diagnosis
- Delirium can be caused by various factors, including infection, disease progression, metabolic state, or medication toxicity 5.
- Delirium etiology can be subtyped, and different etiologies may have different prognostic implications 6.
- The effect of delirium etiologies on outcome may be dependent on the patient's pre-illness functional status and cognition 6.