A child born and raised in Chicago planned to spend the summer on a relative's fruit farm and help with the harvest. The summer passed uneventfully, but several days after the harvest began, the child became jaundiced and very sick. On admission to the hospital the following clinical findings were recorded: in addition to the expected hyperbilirubinemia, the patient was hypoglycemic, had a markedly elevated rise in blood fructose concentration, and was hyperlactic acidemic. Further history taking revealed that during the harvest it was customary for the family to indulge in fruit-filled meals and to snack freely on fruit while carrying out the harvest. The elevated blood fructose in this child was most likely due to which of the following?

Question

Quizplus · Accepted Answer

The symptoms and elevated blood fructose suggest hereditary fructose intolerance, which is caused by a deficiency in hepatic aldolase B.  Hereditary fructose intolerance is a potentially lethal disorder resulting from a lack of aldolase B which is normally present in the liver, small intestine, and kidney cortex. The disorder is characterized by severe hypoglycemia and vomiting following fructose intake. Prolonged intake of fructose by infants with this defect leads to vomiting, poor feeding, jaundice, hepatomegaly, hemorrhage, and, eventually, hepatic failure and death. The hypoglycemia that results following fructose uptake is caused by fructose- 1-phosphate inhibition of glycogenolysis, by interfering with the phosphorylase reaction, and inhibition of gluconeogenesis at the deficient aldolase step. Patients remain symptom free on a diet devoid of fructose and sucrose.

A Child Born and Raised in Chicago Planned to Spend