Hereditary fructose intolerance – two case reports and literature review

Abstract

Hereditary fructose intolerance or fructosemia is an inborn error of fructose metabolism caused by  deficiency of the enzyme fructose- -1-phosphate aldolase. Individuals with this disorder are asymptomatic until fructose, sucrose, or  sorbitol is introduced to the diet. First symptoms usually appear in infancy, after solid food  containing fructose is started. Common acute presentation is nausea, vomiting, and symptoms of  hypoglycaemia. In some infants, acute liver failure may occur. If the disease is unrecognized,  chronic exposure to fructose may cause recurrent vomiting, episodes of abdominal pain, failure to  thrive, chronic liver disease, proximal renal tubular dysfunction, and growth retardation. Many  patients develop strong and protective aversion to sweet-tasting food. Labora- tory findings in  acute crisis include hypoglycaemia, hypophosphataemia,  hyperuricaemia, metabolic acidosis, and  elevated liver enzymes. Complete elimination of fructose from the diet results in dramatic  recovery. The diagnosis of hereditary fructose intoler- ance is confirmed by genetic testing. The  cornerstone of treatment is exclusion of fructose, sucrose, and sorbitol from the diet, which  results in complete alleviation of all signs and symptoms. The aim of this paper is to raise  awareness of the spectrum of clinical symptoms in patients suffering from this rare but treatable  metabolic  disorder, by presenting two patients with different clinical course.