A 9-year-old boy presented with a 2-day history of vomiting, ataxia and reduced consciousness. He had vomited intermittently in the two preceding months, without headaches, visual disturbance or early morning symptoms. He had autism spectrum disorder, and restricted eating since aged 2 years, eating only corn-crisps, Rich Tea biscuits and chips (French fries), and drinking Coca-Cola (containing 10% glucose; figure 1). Recently a dietician had prescribed a multivitamin.edpract;archdischild-2019-317453v1/F1F1F1Figure 1The patient's complete daily food intake over approximately 7 years (2-3 biscuits per day).Dietary analysis revealed an extremely low protein (0.37 g/kg/day) and low fat (0.77 g/kg/day) diet for over 7 years with a caloric intake of 1200 kCal. Estimated requirements were 1512 kCal,¹ 0.92 mg/kg/day of protein² and 1.94 mg/kg of fat (based on 35% of daily calorie intake³).On examination he was encephalopathic, with hepatomegaly and ascites. His height and weight were on the 0.4th-2nd and 9th centiles, respectively. Laboratory results demonstrated glucose 2.7 mmol/L, mild anaemia, raised urea (10.7 mmol/L) with normal creatinine and raised hepatic transaminases, low albumin and elevated creatinine kinase (peak 7809 IU/L). He remained encephalopathic and was intubated for poor respiratory function. Ammonia and blood pH were normal. QUESTION 1: What nutritional/metabolic test(s) would be the next best step?Vitamin B₁ (thiamine) levelsCopper and caeruloplasmin levelsBlood spot for acylcarnitine profilePlasma amino acid profileUrine organic acids QUESTION 2: What potentially dangerous feeding issues in paediatric intensive care exist here?Electrolyte levels and supplementationFat composition of feedsAmino acid composition of feedsVitamin levels QUESTION 3: Why might this patient have had preserved vitamin E levels?Vitamin E is added to rancherosSome vitamin E is obtained from sunlightFrench fries are relatively high in vitamin EMultivitamin preparations QUESTION 4: What metabolic disorders are associated with very low carnitine levels?Organic acidaemiasFatty acid oxidation disordersMitochondrial disorders (disorders of respiratory chain)Maple syrup urine disease (MSUD) Answers can be found on page 01.