Endocrine Abstracts

Introduction: Fructosemia is a rare autosomal recessive genetic metabolic disorder, caused by mutations in the ALDOB (9q22.3) gene, encoding the enzyme aldolase B. This case shows that fructosemia typically causes hypoglycemia. This disorder should be included in differential diagnosis. Prevalence of GDM in women with fructosemia is unknown, but it is a rare condition¹.

Case: Five month old female baby arrived in 1976 to the Hospital of Lithuanian University of Health Sciences, Kauno klinikos with symptoms of fever, vomiting, diarrhea, seizures, when vegetables and sugar were included in child diet. Diagnostic tests showed hypoglycemia. Intravenous glucose admitted and symptoms disappeared but the cause of the hypoglycemia was unknown. In abdomen ultrasound liver was enlarged. Tolerance tests were performed – with glucose, galactose and fructose. The last test showed severe hypoglycemia to 1 mmol/l. Urine test showed excessive amount of fructose (3+). Liver biopsy showed diffuse hepatocytes necrobiosis. Then diet without fructose was prescribed and symptoms disappeared. Patient eliminate products with sugar from diet, vegetables (e.g. carrots) and all fruits. After 26 years in 2001 analysis of aldolase B gene was performed for this female patient and her 2 month old son. They both were homogeneous for the most frequent mutation for aldolase B gene A149P. Fructosemia diagnose was confirmed and the only treatment was eliminate fructose from diet. In 2014 women gave birth twins from another man and they were heterogeneous in aldolase B gene, and has no symptoms of fructosemia. In June of 2018 patient gave birth for a female baby and she has no symptoms for now, but the genetic examination is not performed for the aldolase B gene mutation. Third gestation was complicated by gestational diabetes mellitus. Glucose tolerance test (GTT) was performed during 29 week of third labor. Test results showed GDM: fasting glucose – 4.98 mmol/l, 1 hour after 75 g glucose load – 11.2 mmol/l, after 2 hours – 8.04 mmol/l. There was only dietary treatment needed to treat this condition. After gestation GTT were not performed, but glucose concentration in blood is normal.

Conclusion: Fructosemia is a rare genetic condition, which occurs in infants when fructose is added to the diet. There are no official fructosemia diagnostic or treatment guidelines. Its need to figure in this disease to our differential diagnosis when there is unclear hypoglycemia or digestive tract symptoms.

Literature: 1. Baker P, et al. Hereditary Fructose Intolerance. Genes reviews, 2015 Dec 17.