What labs should be ordered for a patient with memory concerns and a history of alcohol (ethanol) use?

Laboratory Testing for Alcohol-Related Memory Concerns

For patients with memory concerns and alcohol use history, order thiamine level, comprehensive metabolic panel (including glucose, sodium, liver function tests with AST/ALT ratio), complete blood count with MCV, and consider vitamin B12 and folate levels to identify reversible causes of cognitive impairment and assess for alcohol-related organ damage. 1, 2

Essential Laboratory Tests

Thiamine (Vitamin B1) Assessment

• Thiamine deficiency is common in alcohol use disorder and represents a critical, reversible cause of cognitive impairment and memory problems 3, 2
• Thiamine deficiency can cause Wernicke's encephalopathy (often underdiagnosed) and contributes to alcohol-related dementia through multiple mechanisms including blood-brain barrier disruption and brain iron accumulation 3, 4
• Altered thiamine metabolism specifically predicts verbal episodic memory impairments in alcoholic patients 2
• Even subclinical thiamine deficiency may produce early cognitive impairments before overt Wernicke's encephalopathy develops 3

Metabolic Panel Components

Glucose:

• Hypoglycemia is the most frequently identified unexpected laboratory abnormality in patients with alcohol-related presentations 1
• Check glucose immediately as it represents a rapidly reversible cause of altered cognition 1

Sodium:

• Hyponatremia is the second most common metabolic abnormality in alcohol-related presentations 1
• Can contribute to cognitive dysfunction and is often unsuspected based on history alone 1

Liver Function Tests:

• AST and ALT levels help assess alcohol-related liver damage, which is a risk factor for neuropsychological impairments 1, 2
• AST/ALT ratio >2 (especially >3) is highly suggestive of alcohol-related liver disease 1
• Liver fibrosis is a specific risk factor for executive dysfunction and predicts severity of overall neuropsychological impairment 2
• GGT elevation, while having low sensitivity and specificity for alcohol screening alone, provides useful information about liver effects when combined with clinical assessment 1

Hematologic Markers

Mean Corpuscular Volume (MCV):

• Elevated MCV combined with elevated GGT improves sensitivity for detecting chronic alcohol use and associated complications 1
• Macrocytosis can indicate nutritional deficiencies (B12, folate) that contribute to cognitive impairment 2

Complete Blood Count:

• Assess for anemia and macrocytosis as markers of nutritional deficiency 2

Nutritional Assessment

• Vitamin B12 and folate levels should be checked, as malnutrition is associated with more severe neuropsychological impairment profiles in alcohol use disorder 2
• Malnutrition represents a critical risk factor that can help identify patients at particular risk of severe, potentially irreversible neurological complications 2

Important Clinical Context

Limitations of Biomarkers for Screening

• While biomarkers like GGT, MCV, and carbohydrate-deficient transferrin have been studied extensively, they should not be used as systematic screening tools for alcohol misuse, as they are less effective than structured questionnaires like AUDIT 1
• However, in the context of a patient already presenting with memory concerns and known alcohol history, these biomarkers provide valuable information about organ damage and nutritional status that directly impacts cognitive function 1, 2

Risk Stratification

The combination of laboratory findings helps stratify risk for severe cognitive impairment:

• Liver fibrosis + long-term alcohol misuse = risk for executive dysfunction and ataxia 2
• Altered thiamine metabolism = risk for verbal episodic memory impairment 2
• Malnutrition = risk for severe, global neuropsychological impairment 2

Common Pitfalls to Avoid

• Do not rely solely on patient-reported alcohol consumption - cognitive impairment, stigma, and hepatic encephalopathy can all reduce accuracy of self-reporting 1
• Do not assume normal GGT or MCV rules out significant alcohol-related pathology - these markers have limited sensitivity, and many patients with alcohol-related organ damage have normal biochemical tests 1
• Do not delay thiamine supplementation while awaiting laboratory results if Wernicke's encephalopathy is suspected - the condition is underdiagnosed and undertreated, and treatment should begin immediately 3
• Do not overlook the AST/ALT ratio - this simple calculation provides highly specific information about alcohol-related liver disease when >2, especially when >3 1