Table 2 A child with idiopathic ketotic hypoglycemia

A white Danish boy, born at term, birth weight 3425 g, uncomplicated. No siblings. The parents’ history was without symptoms of hypoglycemia or diabetes. Since 4 months’ age, the boy had recurrent vomiting and poor appetite. By age 4 years, poor appetite with recurrent headache, dizziness and loss of consciousness in the morning led to investigations for hypoglycemia. Morning bedside glucose were down to 3.2 mmol/L with blood ketones up to 2.6 mmol/L with repeat KH in the following years. Height and weight were normal. From 8 years, his KH aggravated with glucose down to 2.0 mmol/L, ketones up to 5.6 mmol/L and attacks both in the morning and in the daytime

Normal findings included growth, hematology, electrolytes, liver and kidney counts; IGF1 and IGF-BP3, thyroid hormones, fasting insulin, cortisol response to hypoglycemia, synacthen test cortisol response; urine metabolic screening (except for ketone bodies), plasma amino acids, very long-chained fatty acids, other peroxisomal enxymes and biotinidase; abdominal ultrasound; a 29-gene NGS panel for glycogen storage diseases; skin biopsy fibroblast culture for metabolic enzyme concentrations; and muscle biopsy analyses (histology, electron microscopy, respiratory chain enzymes and pyruvate dehydrogenase activity, mtDNA for larger deletions and missense mutations, lysosomal enzymes group 1). An i.m. glucagon test (0.03 mg/kg) showed a glucose response from 4.3 to 5.4 mmol/L without rebound hypoglycemia or hyperlactatemia. Plasma lactate was repeatedly normal, while plasma pyruvate was mildly elevated on three repeat occasions, 126–138 (ref. 34–80) µmol/L

The boy was monitored with bedside glucometer with ketone sticks and continuous glucose monitoring. Treatment included complex carbohydrates, proteins, snacks between meals, uncooked corn starch and overnight maltose infusion by gastric tube until last follow-up aged 11 years