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Metabolic reasoning
Whole-map thinking. Each case is a chain of cause → effect that ends in the labs: why DKA has ketones and hyperglycemia, why a drinker goes hypoglycemic, why an infant with MCAD deficiency spills no ketones. Walk through the chain on the map, then order it yourself, answer the why questions, or diagnose from the labs.
The confused drinker who got glucose first
A 58-year-old man with chronic alcohol use is found confused with nystagmus, ophthalmoplegia and a wide-based ataxic gait. He was given a bolus of dextrose at the scene and became more confused.
| Lactate | ↑ | ↑ |
| Pyruvate | ↑ | ↑ |
| RBC transketolase activity | ↓ | ↓ |
| Glucose | normal after bolus |
Wernicke encephalopathy (thiamine deficiency)
Three thiamine-dependent enzymes — PDH, α-KG dehydrogenase, transketolase — fail at once; a glucose load with no B₁ makes it worse.
Condition card: Wernicke encephalopathy →Pathway map →Condition card: Korsakoff syndrome →Pathway map →
- Chronic alcohol → poor intake and impaired GI absorption of thiamine → TPP stores fall.
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Pathways involved: PDH & TCA cycle, Glycolysis, HMP shunt (pentose phosphate pathway). Drill them one at a time in Metabolic pathways.