ORIGINAL ARTICLE

Glucose and leucine kinetics in idiopathic ketotic hypoglycaemia

O A Bodamer¹, K Hussein², A A Morris³, C-D Langhans⁴, D Rating⁴, E Mayatepek⁵, J V Leonard²

¹ Biochemical Genetics and National Neonatal Screening Laboratories, University Children’s Hospital Vienna, Vienna, Austria
² Endocrinology, Metabolism, Nutrition & Genetics, Institute of Child Health, London, UK
³ Willink Biochemical Unit, Royal Manchester Children’s Hospital, Manchester, UK
⁴ Department of Paediatric Neurology, University Children’s Hospital, Heidelberg, Germany
⁵ Department of General Paediatrics, University Children’s Hospital, Düsseldorf, Germany

Correspondence to:
Prof. Dr O Bodamer
Biochemical Genetics and National Neonatal Screening Laboratories, Department of General Pediatrics, University Children’s Hospital Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria; olaf.bodamer{at}meduniwien.ac.at

Aims: To investigate glucose and leucine kinetics in association with metabolic and endocrine investigations in children with ketotic hypoglycaemia (KH) in order to elucidate the underlying pathophysiology.

Methods: Prospective interventional study using stable isotope tracer in nine children (mean age 4.23 years, range 0.9–9.8 years; seven males) with KH and 11 controls (mean age 4.57 years, range 0.16–12.3 years; four males).

Results: Plasma insulin levels were significantly lower in KH compared to subjects in the non-KH group. Plasma ketone body levels were significantly higher in KH than in non-KH. Basal metabolic rate was significantly higher in subjects with KH (45.48±7.41 v 31.81±6.72 kcal/kg/day) but the respiratory quotients were similar in both groups (KH v non-KH, 0.84±0.05 v 0.8±0.04. Leucine oxidation rates were significantly lower in children with KH (12.25±6.25 v 31.96±8.59 µmol/kg/h). Hepatic glucose production rates were also significantly lower in KH (3.84±0.46 v 6.6±0.59 mg/kg/min).

Conclusions: KH is caused by a failure to sustain hepatic glucose production rather than by increased glucose oxidation rates. Energy demand is significantly increased, whereas leucine oxidation is reduced.

Abbreviations: BMI, body mass index; BMR, basal metabolic rate; GC-MS, gas chromatography-mass spectrometry; KH, ketotic hypoglycaemia; KIC, ketoisocaproic acid; NEFA, non-esterified fatty acids; NHS, National Health Service; RQ, respiratory quotient; MAT, mitochondrial acetoacetyl CoA thiolase; MSUD, maple syrup urine disease; SCOT, succinyl CoA oxoacid transferase; SD, standard deviation

Keywords: tracer; isotope; ketone body; mass spectrometry; energy expenditure

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