What is the first parenteral nutritional supplement to administer to a patient with acute alcohol intoxication and suspected malnutrition?

Thiamine Must Be Given First

In a patient with acute alcohol intoxication, alcohol use disorder, and food insecurity requiring parenteral nutritional supplementation, thiamine must be administered first—before any glucose-containing fluids—to prevent precipitating Wernicke's encephalopathy. 1, 2

Critical Rationale for Thiamine-First Protocol

Risk of Wernicke's Encephalopathy

• Thiamine-deficient patients who receive glucose without prior thiamine supplementation can develop acute Wernicke's encephalopathy, as glucose metabolism requires thiamine as an essential cofactor 2, 3
• This patient has multiple high-risk features: alcohol use disorder (30-80% have thiamine deficiency), food insecurity indicating malnutrition, and acute intoxication with neurological symptoms (confusion, ataxia) 2, 4
• The clinical presentation already suggests possible early thiamine deficiency, as confusion and ataxic gait are cardinal features of Wernicke's encephalopathy 2, 4

Evidence-Based Dosing Protocol

• For high-risk patients with alcohol use disorder and malnutrition, administer thiamine 100-300 mg IV immediately before any glucose-containing fluids or parenteral nutrition 1, 2
• This dose should be given for at least 3-4 days from admission 2
• If Wernicke's encephalopathy is suspected (which this patient's symptoms suggest), increase to 500 mg IV three times daily (total 1,500 mg/day) 2, 4

Why Not the Other Options First

• Dextrose (Option A) is contraindicated as the first intervention because administering glucose before thiamine can precipitate or worsen Wernicke's encephalopathy in thiamine-deficient patients 1, 2, 3
• Magnesium (Option C), while important for thiamine-dependent enzyme function and commonly deficient in alcoholics, should be given after or concurrently with thiamine, not before 1
• Folate (Option B) is less urgently needed and does not carry the same risk of precipitating acute neurological deterioration 2

Refeeding Syndrome Prevention

• This patient is at extremely high risk for refeeding syndrome given the combination of alcohol use disorder, food insecurity, and likely prolonged malnutrition 1, 5
• The ESPEN guidelines specifically recommend administering thiamine before commencing parenteral nutrition in malnourished patients to prevent both Wernicke's encephalopathy and refeeding syndrome 1
• For refeeding syndrome prevention, give 300 mg IV thiamine before initiating nutrition therapy, then 200-300 mg IV daily for at least 3 more days 2

Clinical Implementation Algorithm

1. Immediate administration: Give thiamine 100-300 mg IV as the first intervention 2
2. Assess severity: If any signs of Wernicke's encephalopathy (confusion, ataxia, ophthalmoplegia), increase to 500 mg IV three times daily 2, 4
3. Then address other deficiencies: After thiamine, correct magnesium, phosphate, and potassium before starting nutrition 1
4. Start nutrition cautiously: Begin with low caloric intake (15-20 kcal/kg/day) and advance gradually to prevent refeeding syndrome 1, 5
5. Continue thiamine: Maintain 100-300 mg IV daily for 3-4 days, then transition to oral thiamine 100-250 mg daily for 2-3 months 2, 4

Common Pitfalls to Avoid

• Never administer glucose-containing IV fluids before thiamine in alcohol use disorder patients—this is the most critical error that can precipitate irreversible neurological damage 2, 3
• Do not rely on oral thiamine in acute settings with alcohol-related gastritis, as absorption is severely impaired; IV route is mandatory 2, 4
• Do not wait for laboratory confirmation of thiamine deficiency—the benefit-risk ratio strongly favors empiric treatment, as thiamine has no established toxicity limit and excess is simply excreted in urine 2, 6
• Do not overlook the serum ethanol level of 0.24% (240 mg/dL), which is three times the legal limit and confirms significant ongoing alcohol exposure, further supporting high thiamine deficiency risk 2

Answer: D. Thiamine