ESPE Abstracts

Introduction: Diagnosing hypoglycemia-associated metabolic disorders is challenging and necessitates a methodical approach. Unlike idiopathic ketotic hypoglycemia (starvation hypoglycemia), fructose 1,6-bisphosphatase deficiency is an uncommon metabolic disorder characterized by a defect in gluconeogenesis. This disorder also causes lactic acidosis, hypertriglyceridemia, hyperuricemia, and ketonuria. This case report describes two siblings diagnosed with fructose 1,6-bisphosphatase deficiency.

Case Reports:

Case 1: A 5.8-year-old male experienced ketotic hypoglycemic episodes accompanied by vomiting, abdominal pain, and occasionally fever. These episodes were first noted when the patient was nine months old and have occurred approximately fifteen times since then. Physical examination revealed normal weight (0.34 SDS), height (0.6 SDS), body mass index (-0.16 SDS), and head circumference (-1.47 SDS) for chronological age. Neither organomegaly nor hepatosteatosis was detected.

Case 2: A 2.3-year-old male experienced hypoglycemic episodes during the newborn and early childhood years. Unlike his brother, he had microcephaly (SDS -2.31), hepatomegaly, and hepatosteatosis. The clinical features of his hypoglycemic episodes were similar to his brother's. The parents were consanguineous, and their aunt had died due to hypoglycemia at the age of three. All hypoglycemic episodes in both siblings occurred after 8-12 hours of fasting and were characterized by vomiting, fever (sometimes), inability to feed, weakness, and sleepiness. Critical serum samples revealed metabolic acidosis, hyperlactatemia, hypertriglyceridemia, hyperuricemia, elevated liver function tests, and ketonuria. The patients were advised to feed frequently and consume 1-2 grams of uncooked corn starch per kilogram of body weight every six hours. Hypoglycemic episodes recurred when the uncooked corn starch was omitted. Clinical exome sequencing of both siblings identified a homozygous deletion in exon 1 of the FBP1 gene, confirming the diagnosis of fructose 1,6-bisphosphatase deficiency.

Conclusion: The causes of hypoglycemia in childhood are varied, and their differential diagnosis is crucial for appropriate treatment and follow-up. Differentiating between idiopathic ketotic hypoglycemia, the most prevalent cause of hypoglycemia in children, and other metabolic disorders is essential. Fructose 1,6-bisphosphatase deficiency should be considered in the differential diagnosis of childhood hypoglycemia when metabolic acidosis, lactic acidosis, hypertriglyceridemia, hyperuricemia, consanguinity between parents, and a family history of similar symptoms are present.