Laboratory Testing for Memory Concerns
All patients with memory concerns should receive a comprehensive Tier 1 laboratory panel that includes: complete blood count with differential, complete metabolic panel (Chem-20) with renal and hepatic function, electrolytes, glucose, calcium, magnesium, phosphate, thyroid-stimulating hormone (TSH), vitamin B12, homocysteine, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). 1
Core Laboratory Panel (Tier 1 - Required for All Patients)
The following tests should be obtained in all, or almost all, patients presenting with cognitive or behavioral symptoms as part of the standard "cognitive lab panel": 1
Hematologic Studies
- Complete blood count (CBC) with differential to assess for anemia, infection, or hematologic disorders that may contribute to cognitive symptoms 1
Metabolic and Electrolyte Assessment
- Complete metabolic panel (Chem-20) including renal function (BUN, creatinine), hepatic function (AST, ALT, alkaline phosphatase, bilirubin), electrolytes (sodium, potassium, chloride, bicarbonate), glucose, calcium, magnesium, and phosphate 1
- These tests identify metabolic derangements that commonly contribute to cognitive impairment 1
Endocrine Evaluation
- Thyroid-stimulating hormone (TSH) to screen for hypothyroidism or hyperthyroidism, both of which can present with cognitive symptoms 1
Nutritional and Inflammatory Markers
- Vitamin B12 level to detect deficiency that can cause reversible cognitive impairment 1
- Homocysteine level as an additional marker of B12/folate deficiency and vascular risk 1
- C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) to assess for inflammatory conditions 1
Additional Considerations for Individualized Testing
Beyond the core Tier 1 panel, additional laboratory studies may be warranted based on specific clinical circumstances: 1
Cardiovascular Risk Assessment
- Lipid panel for patients with vascular risk factors 1
- Hemoglobin A1C for diabetes screening or monitoring 1
Specialized Testing (When Clinically Indicated)
- Electrocardiogram (ECG) for cardiac evaluation 1
- Serum and plasma collection for potential biomarker analysis in research settings 1
- DNA collection for genetic testing when familial dementia is suspected 1, 2
Critical Context for Laboratory Interpretation
The routine dementia workup rarely identifies reversible causes of cognitive impairment in isolation. 3 While laboratory abnormalities may be detected, correction of these abnormalities often does not improve the cognitive course, as most patients have underlying neurodegenerative disease such as Alzheimer's disease or frontotemporal dementia. 3
Key Implementation Points
Laboratory testing should be performed in conjunction with structural brain imaging (MRI preferred, CT if MRI contraindicated) as part of comprehensive Tier 1 diagnostic evaluation 1
The laboratory panel aids primarily in recognizing and treating comorbid conditions that may contribute to (rather than cause) cognitive symptoms 1
Do not rely on laboratory results alone - integrate findings with comprehensive history (including informant report), validated cognitive testing (such as MoCA), functional assessment, and neuroimaging 1, 4
For patients with negative standard workup but concerning family history, consider extended genetic testing for non-Alzheimer monogenic mutations (e.g., progranulin gene) 2
Common Pitfalls to Avoid
Do not assume normal laboratory values exclude significant cognitive impairment - most patients with dementia have normal or only mildly abnormal laboratory results 3
Do not delay cognitive assessment or neuroimaging while waiting for laboratory results - these should be obtained concurrently 1
Do not over-interpret isolated laboratory abnormalities - clinical correlation with cognitive testing and imaging is essential 3