Background: Hyperinsulinism/hyperammonaemia (HI/HA) syndrome is associated with postprandial hypoglycaemia and mild hyperammonemia. There is increased insulin release following protein ingestion, which is amenable to diaxozide therapy. While developmental delay and normoglycaemic seizures can also occur, hepatomegaly has not been reported. We report a child with HI/HA and hepatomegaly, mild learning difficulty and obesity, who was initially mistaken to have glycogen storage disease (GSD).
Objective and hypotheses: The child first presented at 9 months of age with hepatomegaly and hypoglycaemic seizures. Liver biopsy was suggestive of metabolic hepatopathy and he was managed as GSD. Despite frequent feeds and corn starch, intermittent hypoglycaemic seizures continued, and he was re-evaluated at 5 years of age. This time, mild learning difficulty, obesity, and mid-afternoon lethargy/drowsiness and brief normo-glycaemic seizures were noted, while hepatomegaly had regressed. His capillary blood glucose levels were relatively low throughout the day.
Method: The child tolerated a supervised fast for 18 hours, without hypoglycaemia, but subsequently had a hypoglycaemic seizure, an hour after a meal containing rice, dhal and egg. During the in-ward seizure, child had detectable serum insulin and absent urine ketone bodies. HI/HA was suspected and a protein loading test was performed.
Results: Symptomatic hypoglycaemia occurred within an hour of protein loading, and blood glucose increased by 40 mg/dl with IV glucagon, while serum ammonia was elevated. These results were compatible with HI/HA. Oral dioxide and a low protein (leucine) diet were prescribed, and corn starch and frequent feeding discontinued.
Outcome: A rapid clinical improvement was seen, with disappearance of lethargy and hypoglycaemia, and improvement in obesity. HI/HA can be biochemically confirmed and managed easily if suspected, emphasising the importance of awareness of this entity.
Conclusion: The presence of hepatomegaly deterred from the correct diagnosis at presentation. However the correct diagnosis was uncovered by a detailed history, and simple ward procedures. This is an important condition for paedaitrci endocrinologists to be aware of as the diagnosis and treatment can be instituted even in low resource settings without genetic testing facilities.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology