Fructose Intolerance & Hypoglycemia

Hereditary fructose intolerance, or HFI, is a rare genetic condition that affects your body's ability to digest fructose, a sugar found in fruits. This condition is typically diagnosed in infancy and can lead to a number of harmful health conditions, including low blood sugar or hypoglycemia. Recognizing the symptoms of fructose intolerance in your child can help to minimize harmful effects.

Significance

When you have HFI, you lack an enzyme called aldolase B. Fructose in the body is broken down into several parts, the last of which is fructose-1-phosphate aldolase. Without aldolase B, your body cannot complete the final conversion step, which is converting the fructose to glucose, the form of energy for your cells. Over time, the buildup of fructose in your body can lead to damage in the liver, kidneys and intestines.

Hypoglycemia

Hypoglycemia is a condition where your body does not have enough glucose. In the case of HFI, your body has the fructose to break down into glucose but cannot complete the cycle. After you eat fruits, this can lead to severe hypoglycemia where your blood sugar levels dip below 70 mg/dL. This can be very harmful to the body, causing damage that leads to loss of consciousness, seizures, nerve damage and slipping into a coma.

Symptoms

Signs you can experience hypoglycemia-related HFI include cold sweats, convulsions, fast heartbeat, irritability, tingling or difficulty sleeping. These symptoms are ones that can be observed in infants. Other symptoms that can be experienced include double vision, headache, tingling skin or tiredness. If this occurs after eating fruits, this can potentially signal an HFI problem.

Misconception

Fructose malabsorption and HFI often are confused. However, fructose malabsorption is a condition that affects your ability to digest fructose and can cause similar symptoms to HFI, including pain, gas, bloating and diarrhea. Fructose malabsorption is not considered to be as serious a condition because it does not cause hypoglycemia and lead to liver or kidney damage. Of the two conditions, HFI is considered to be the more serious.

Diagnosis and Treatment

Diagnosing fructose involves administering a hydrogen breath test, which can measure for a variety of sugars, including glucose, lactose, fructose and sucrose. The presence of fructose in the breath test can indicate a possible fructose intolerance. If a physician diagnoses you or your infant with HFI, he will recommend an avoidance diet, eliminating foods like fruits, honey, powdered sugar, fruit juices, flavored water, sports drinks and sweetened milk.