Fructose-1,6-diphosphatase deficiency: glycerol excretion during fasting test.

A Turkish boy had suffered since the age of 10 months from recurrent attacks of severe metabolic acidosis and hypoglycaemia precipitated by moderate respiratory tract infections. A liver biopsy showed lack of fructose 1,6-diphosphatase and absence of phosphorylase. The patient died in shock following fructose ingestion. Upon fasting, acidosis with increased lactate and glycerol excretion was found. Findings indicate that, in this inherited disorder of gluconeogenesis, lactic acidosis combined with increased glycerol excretion upon fasting are of diagnostic importance.