What is fructosuria?
Fructosuria is a rare but benign inherited metabolic disorder. It is characterized by the excretion of fruit sugar (fructose) in the urine. Normally, no fructose is excreted in the urine. This condition is caused by a deficiency of the enzyme fructokinase in the liver. This enzyme is needed for the synthesis of glycogen (the body's form of stored energy) from fructose. The presence of fructose in the blood and urine may lead to an incorrect diagnosis of diabetes mellitus.
What are the symptoms for fructosuria?
Fructose is a sugar that occurs naturally in fruits, vegetables, and honey. When a person cannot digest or absorb fructose, they may have fructose intolerance known as fructosuria.
When a person has an intolerance to fructose, they may experience bloating, abdominal pain, and diarrhea.
People with a more severe form of fructose intolerance called hereditary fructose intolerance will develop symptoms in infancy.
Infants with HFI
Infants with HFI face symptoms like prolonged vomiting, failure to thrive, jaundice, and growth retardation. There may be occasional episodes of unconsciousness. Other symptoms include enlargement of the liver and frequent cirrhosis, and a tendency towards gastrointestinal bleeding because of a deficiency of clotting factors. infants may exhibit growth delays and even experience malnutrition
Patients with HFI usually develop a strong dislike for sweets and fruit.
It is better to recognize the intolerance early to avoid liver, kidney, and small intestine damage.
If a person experiences any symptoms or is concerned that they cannot tolerate fructose, they should seek treatment to relieve symptoms and improve their quality of life.
Hereditary fructose intolerance may be life-threatening without treatment.
If a parent suspects that a child cannot digest fructose, they should contact a doctor without delay.
What are the causes for fructosuria?
Essential pentosuria is caused by mutations in the DCXR gene. This gene provides instructions for making a protein called dicarbonyl and L-xylulose reductase (DCXR), which plays multiple roles in the body. One of its functions is to perform a chemical reaction that converts a sugar called L-xylulose to a molecule called xylitol. This reaction is one step in a process by which the body can use sugars for energy.
DCXR gene mutations lead to the production of altered DCXR proteins that are quickly broken down. Without this protein, L-xylulose is not converted to xylitol, and the excess sugar is released in the urine.
While essential pentosuria is caused by genetic mutations, some people develop a non-inherited form of pentosuria if they eat excessive amounts of fruits high in L-xylulose or another pentose called L-arabinose. This form of the condition, which disappears if the diet is changed, is referred to as alimentary pentosuria. Studies show that some drugs can also cause a form of temporary pentosuria called drug-induced pentosuria. These non-inherited forms of the condition also do not cause any health problems.