Function tests

Fructose intolerance.

Pathopsychology:
In hereditary fructose intolerance, a fructose-1-phosphate-aldolase-deficiency leads to accumulation of fructose-1-phosphate in the liver, the kidneys and the intestinal mucosa. The incidence is approximately 1:20.000. After fructose intake there will be nausea, abdominal pains, hypoglycemia, hyperuricemia, aminoaciduria, uricosuria and fructosuria.

Fructose, glucose

Sodium fluoride blood. Hemolysate is not suitable.

1. Initial blood extraction in empty-stomached patient.
2. Oral administration of 1,0 – 1,5 g fructose / kg body weight as a 10 % solution in tea or water.
3. Blood extractions 30, 60, 90 and 120 min after fructose intake.

Normal values:

Fructose increase of more than 6 mg/dl

Maximal fructose concentration up to 15 mg/dl.

Reaching of initial levels after 120 min.

Fructose intolerance:

Highest fructose concentration: more than 40 mg/dl.

Glucose decrease.

Please note:

• Securing of diagnosis is by intravenous fructose tolerance test (due to possible complications only possible under inpatient conditions) and evidence of fructose-1-phosphate-aldolase deficiency in either a liver biopsy or small intestine biopsy.
• More common than the hereditary fructose intolerance is the fructose malabsorption, with clinical signs of flatulence, winds, bellyache and watery diarrhea after intake of food containing fructose.