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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.
Jaundice, vomiting and E. coli sepsis in a 5-day-old
A 5-day-old breastfed neonate has vomiting, poor feeding, jaundice and hepatomegaly. Blood cultures grow E. coli. The ophthalmologist notes early lens opacities.
| Urine reducing substances | positive | + |
| Urine glucose oxidase | negative | |
| Bilirubin | ↑ (mixed) | ↑ |
| AST/ALT | ↑ | ↑ |
| RBC GALT activity | absent | ↓↓ |
| Galactose-1-phosphate (RBC) | ↑↑ | ↑ |
Classic galactosemia (GALT deficiency)
Galactose-1-phosphate is the toxin; galactitol from aldose reductase adds the cataract; neutrophil dysfunction adds the E. coli.
Condition card: Galactosemia (GALT deficiency) →Pathway map →
- Lactose (milk) → lactase → glucose + galactose; galactokinase makes galactose-1-P normally.
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Pathways involved: Galactose metabolism (Leloir pathway), NADPH — sources and what needs it. Drill them one at a time in Metabolic pathways.