Patients suffering from HFI develop and grow normally while being only breastfed. Problems usually start to appear at the time of weaning, when fructose is first introduced into the diet through foods containing fructose, sucrose (a disaccharide containing glucose and fructose units), or sorbitol. Consumption of fructose-containing foods results in hypoglycemia, lactic acidosis, and ketosis and causes difficulties in feeding, repeated vomiting, and abdominal discomfort. In the long run, these symptoms will lead to failure to thrive. Continued feeding with sugars that either contain fructose or are converted to fructose may lead to liver and kidney failure, convulsions, coma, and possibly death [1] [2] unless the problem is addressed.

Patients who live beyond infancy develop a strong dislike for foods containing fructose, mainly fruits and sweets, and continue to have unfavorable reactions (vomiting and hypoglycemia) following fructose ingestion throughout the rest of their lives. In general, there is very little tooth decay in adults with HFI, which, in itself, may be an indication of the disease, and is probably due to the voluntary exclusion of sweets from their diet.

• Pallor

  The most frequent clinical findings were hepatomegaly (18X), pallor (14X), haemorrhages (13X). Ascites, oliguria, tachypnoea, fever, splenomegaly and rickets were less frequent. [ncbi.nlm.nih.gov]

  These sweeteners are not common in formulas used today. [5] Symptoms such as vomiting, nausea, restlessness, pallor, sweating, trembling and lethargy can also first present in infants when they are introduced to fruits and vegetables. [en.wikipedia.org]

  The patient was a healthy, breastfed infant; however, in his fourth month he developed an acute episode of repetitive vomiting, irritability, pallor, and shock. [pediatrics.aappublications.org]

  The result is pallor, sweating, trembling, fear, convulsions and ultimately loss of consciousness because the brain cannot tolerate being deprived of glucose. [independent.co.uk]

• Unconsciousness

  Herein we report on a case of hereditary fructose intolerance with initial presentation of episodic unconsciousness, seizure, hypoglycemia, hepatomegaly, and abnormal liver function since the patient was 11 months old. [ncbi.nlm.nih.gov]

  While it is acceptable for sufferers to eat the lactose in milk, and pure glucose, anything containing fructose - sugar in tea, cake, even an apple - can cause severe stomach pains, even convulsions and unconsciousness. [independent.co.uk]

  […] glucagon injection (a medication used in an emergency to increase blood glucose) and seek emergent treatment when the child has the following symptoms: inability to swallow numbness in mouth or tongue poor coordination poor concentration, confusion unconsciousness [healthofchildren.com]

• Fever

  Ascites, oliguria, tachypnoea, fever, splenomegaly and rickets were less frequent. Laboratory findings were indicative of disturbed hepatic and renal tubular function and also of disturbed intermediary metabolism (hypokaliaemia, hypophosphataemia). [ncbi.nlm.nih.gov]

  Initial symptoms include severe abdominal pain, vomiting that can lead to dehydration, and unexplained fever. Other symptoms include extreme thirst and excessive urination and sweating. There is also a loss of appetite and a failure to grow. [healthofchildren.com]

  Initial symptoms include vomiting, dehydration, and unexplained fever. Other symptoms include extreme thirst and excessive urination and sweating. There will also be a loss of appetite and a failure to grow. [medical-dictionary.thefreedictionary.com]

  Tell-tale signs are skin rashes, hives, itching, a runny nose at mealtimes, asthma and hay fever. Lactose and fructose intolerance co-exist in approximately 20-30% of individuals. [foodintolerances.org]

• Turkish

  Two nonsense mutations create opal termination codons: R3op (C-- T, Arg3-- ter, exon 2) was found in homozygous form in four affected members of a large consanguineous Turkish pedigree and R59op (C-- T, Arg59-- ter, exon 3) was found on one allele in [ncbi.nlm.nih.gov]

  Mutation analysis in Turkish patients with hereditary fructose intolerance. J Inherit Metab Dis 2001;24:523-526. [15] Esposito G, Santamaria R, Vitagliano L, et al. [em-consulte.com]

• Collapse

  In three of them, neurological involvement was related to the acute hepatic toxicity of fructose (hypoglycemia, abnormal coagulation, cardiovascular collapse); in the other two, such a relationship could not be demonstrated. [ncbi.nlm.nih.gov]

• Vomiting

  We report on an infant with suspected HFI who presented with repeated episodes of vomiting and hypotension after ingestion of fruit-containing meals. The first episode occurred at age 4 months. [ncbi.nlm.nih.gov]

  Infants will present with feeding difficulties, vomiting, failure to thrive and symptoms of hypoglycemia and acidosis. [symptoma.com]

• Nausea

  In HFI, fructose ingestion generally induces gastro-intestinal (nausea and vomiting, abdominal pain, meteorism) and hypoglycemic symptoms. Fasting is well tolerated. [ncbi.nlm.nih.gov]

  These sweeteners are not common in formulas used today. [5] Symptoms such as vomiting, nausea, restlessness, pallor, sweating, trembling and lethargy can also first present in infants when they are introduced to fruits and vegetables. [en.wikipedia.org]

  The following are observed: HFI is asymptomatic in nature, before the intake of fructose Initial signs include diarrhea, vomiting, nausea, swollen abdomen with pain, hypoglycemia (low blood sugar). [dovemed.com]

  Common Features of the Disorder Failure to thrive in infancy Nausea Bloating Abdominal pain Diarrhea Vomiting Low blood sugar Jaundice Enlarged liver Liver disease (i.e. cirrhosis) Seizures Coma Growth delays Kidney failure Prognosis Hereditary Fructose [evolvegene.com]

• Failure to Thrive

  In the long run, these symptoms will lead to failure to thrive. [symptoma.com]

  Symptoms are present only after the ingestion of fructose, which leads to brisk hypoglycemia, and an individual with continued ingestion will exhibit vomiting, abdominal pain, failure to thrive, and renal and liver failure. [ncbi.nlm.nih.gov]

• Food Intolerance

  You may even be suffering from more than one food intolerance. The research indicates that doing nothing can be a risk. Undiagnosed food intolerance can cause serious long-term health problems like osteoporosis, anaemia and many others. [foodintol.com]

  On the Food Intolerance Network website we will use the term "fructose malabsorption", and sometimes "fructose intolerance", but in that case we never talk about hereditary fructose intolerance (HFI) unless this is referred to specifically! [food-intolerance-network.com]

  Living with Food Intolerance London, UK: Sheldon Press, 2006. Saville, A., Haynes, A. Food Intolerance Bible New York, NY: ThorsonsElement (Harpercollins), 2005. Minocha, A. Handbook of Digestive Diseases Thorofare, NJ: Slack Incorporated, 2004. [diet.com]

• Recurrent Vomiting

  Clinical description HFI usually presents in infancy at the time of weaning (when fructose is added to the diet), manifesting with hypoglycemia, lactic acidosis, ketosis with recurrent vomiting, abdominal pain and systemic manifestations following consumption [orpha.net]

  Clinical features include-Recurrent vomiting, abdominal pain, and hypoglycemia that may be fatal. [usmle.biochemistryformedics.com]

  Clinical features include- Recurrent vomiting, Abdominal pain, and Hypoglycemia that may be fatal. [namrata.co]

• Hepatomegaly

  He presented with episodic unconsciousness, seizures, hypoglycemia, hepatomegaly and abnormal liver function. [ncbi.nlm.nih.gov]

• Oliguria

  Ascites, oliguria, tachypnoea, fever, splenomegaly and rickets were less frequent. Laboratory findings were indicative of disturbed hepatic and renal tubular function and also of disturbed intermediary metabolism (hypokaliaemia, hypophosphataemia). [ncbi.nlm.nih.gov]

• Seizure

  Herein we report on a case of hereditary fructose intolerance with initial presentation of episodic unconsciousness, seizure, hypoglycemia, hepatomegaly, and abnormal liver function since the patient was 11 months old. [ncbi.nlm.nih.gov]

  Some infants have a more severe reaction to such sugars with lethargy, seizures and coma. Older children and adults develop a protective aversion to fruits and sweets. [disorders.eyes.arizona.edu]

  Other complications may include seizures, gout, low blood sugar, bleeding and even death. Foods to Avoid Removing fructose from your child’s diet is the only way to prevent symptoms and reduce the risk of complications, like liver disease. [healthyeating.sfgate.com]

  Common Features of the Disorder Failure to thrive in infancy Nausea Bloating Abdominal pain Diarrhea Vomiting Low blood sugar Jaundice Enlarged liver Liver disease (i.e. cirrhosis) Seizures Coma Growth delays Kidney failure Prognosis Hereditary Fructose [evolvegene.com]

• Irritability

  Moreover, hypoglycemia induced by fructose absorption, unexplained liver disease, irritable bowel syndrome or familial gout in an adult is suggestive of the diagnosis. [ncbi.nlm.nih.gov]

  Mots clés : Vitamine C, Hypoglycémie, Intolérance héréditaire au fructose, Intestin irritable, Goutte Keywords: Vitamin C, Hypoglycemia, Hereditary fructose intolerance, Irritable bowel, Gout The full text of this article is available in PDF format. [em-consulte.com]

  /sucrose-containing foods Doing well after eating foods without fructose/sucrose The early symptoms of fructose intolerance may resemble those of galactosemia: irritability, jaundice, vomiting, convulsions and an enlarged liver and spleen. [foodreactions.co.uk]

  […] accumulation of fructose-1-phosphate which, over time, results in the death of liver cells. [1] This accumulation has downstream effects on gluconeogenesis and regeneration of adenosine triphosphate (ATP). [1] Symptoms of HFI include vomiting, convulsions, irritability [en.wikipedia.org]

• Confusion

  I mention this because, even removing FM and HFI from your search, fructose is plastered everywhere, just adding to the confusion. [thefriendlygourmand.com]

  HEREDITARY fructose intolerance is an uncommon metabolic disorder, characterized by symptoms of nausea, vomiting, malaise, substernal pain, excessive sweating, tremor, confusion, coma and convulsions, that follows the ingestion of foods containing fructose [nejm.org]

  Hereditary fructose intolerance should not be confused with a condition called fructose malabsorption. [ghr.nlm.nih.gov]

  However, HFI is most commonly confused with fructose malabsorption. This is a non-life threatening and much more common condition. This site contains a helpful comparison of the two conditions. The treatment for both is similar. [sweetpoison.wikidot.com]

• Lethargy

  Because this non-immunoglobulin E-mediated gastrointestinal food hypersensitivity manifests as profuse, repetitive vomiting, often with diarrhea, leading to acute dehydration and lethargy, it may be misinterpreted as HFI. [ncbi.nlm.nih.gov]

  Case details A 3-year-old boy was brought to the emergency department after several episodes of vomiting and lethargy. [namrata.co]

  Some infants have a more severe reaction to such sugars with lethargy, seizures and coma. Older children and adults develop a protective aversion to fruits and sweets. [disorders.eyes.arizona.edu]

  These sweeteners are not common in formulas used today. [5] Symptoms such as vomiting, nausea, restlessness, pallor, sweating, trembling and lethargy can also first present in infants when they are introduced to fruits and vegetables. [en.wikipedia.org]

  QUESTION OF THE DAY A 3-month-old girl is brought to the pediatrician due to fussiness and lethargy. [usmle.biochemistryformedics.com]

Taking a detailed dietary history in individuals suspected of hereditary fructose intolerance is a crucial component of diagnosis. Infants will present with feeding difficulties, vomiting, failure to thrive [1] and symptoms of hypoglycemia and acidosis [3]. In older children and adults, the history is expected to show episodes of food refusal: affected infants and children will recoil from sweets after being taken ill several times. Sometimes, apparently healthy adults are given a diagnosis of HFI based on dietary history. As mentioned, a complete lack of tooth decay can also serve as an indicator for hereditary fructose intolerance.

A comprehensive history has to be followed up with laboratory tests and physical examination. There are several tests to verify suspected HFI, i.e. fructose 1-phosphate aldolase deficiency: one test determines if there is a reducing sugar in the urine that is not glucose. Reducing sugars are easily detected with Clinitest; if this is positive, the identity of the sugar can be established by further tests, such as thin-layer chromatography or enzyme assays [4]. Another test is the measurement of the aldolase enzyme activity in liver or intestinal mucosal biopsies: the enzyme’s function is impaired in HFI patients [5]. The latter test has been, to a large extent, superseded by molecular methods, which are non-invasive. DNA analysis can be performed using leukocytes. Sequencing of the aldolase gene (located on chromosome 9) will, in all probability, diagnose the disease and unambiguously identify the mutation responsible for it [6] [7] [8 [9] [10] [11]. These tests can define the mutational spectrum and can serve as the basis for designing targeted mutational tests [11].

The intravenous fructose tolerance test [5] is also non-invasive but has to be performed in a controlled hospital environment because of the hazards associated with fructose administration to HFI patients [1] [3]. Oral fructose tolerance testing should not be used because of the danger of severe gastrointestinal reaction. Observing relief of symptoms in response to the dietary exclusion of fructose also has strong diagnostic value.

Hepatic function tests should be performed to evaluate whether the liver is damaged. Patients, who do not receive treatment, usually show indications of hepatocellular injury, which may not be reversible [2]; the histology shows multiple abnormalities, such as fatty deposits in peripheral lobules. Except in cases where there is strong evidence for liver disease, liver biopsy should not be used for diagnosis.

Urine tests may show elevated levels of glucose, proteins, and amino acids, characteristic of renal Fanconi syndrome, which may be caused by fructose intolerance. Decreased tubular reabsorption of bicarbonate [12] lowers the blood bicarbonate concentration and contributes to metabolic acidosis. To test for tubular acidosis, plasma electrolyte levels should be determined.

• Capnocytophaga Ochracea

  Specific antibody titers from whole saliva and serum to Actinobacillus actinomycetemcomitans gamma 4, Bacteroides gingivalis, and Capnocytophaga ochracea were determined with ELISA. Finally the subgingival plaque was analyzed by culture. [ncbi.nlm.nih.gov]

• Capnocytophaga

  Specific antibody titers from whole saliva and serum to Actinobacillus actinomycetemcomitans gamma 4, Bacteroides gingivalis, and Capnocytophaga ochracea were determined with ELISA. Finally the subgingival plaque was analyzed by culture. [ncbi.nlm.nih.gov]

• Liver Biopsy

  A second liver biopsy 10 months later had normal aldolase B activity towards fructose-1-phosphate and a fructose tolerance test was also normal. A possible explanation for these findings is proposed. [ncbi.nlm.nih.gov]

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2. Odièvre M, Gentil C, Gautier M, Alagille D. Hereditary fructose intolerance in childhood. Diagnosis, management, and course in 55 patients. Am J Dis Child. 1978 Jun;132(6):605-608.
3. Ali M, Rellos P, Cox TM. Hereditary fructose intolerance. J Med Genet. 1998;35:353–65.
4. Steinmann B, Santer R. Disorders of fructose metabolism. In: Saudubray JM, van den Berghe G, Walter JH, eds. Inborn Metabolic Diseases: Diagnosis and Treatment. Berlin: Springer-Verlag; 2012;157–165.
5. Steinmann B, Gitzelmann R. The diagnosis of hereditary fructose intolerance. Helv Paediatr Acta. 1981;36:297–316
6. Bouteldja N, Timson DJ. The biochemical basis of hereditary fructose intolerance. J Inherit Metab Dis. 2010 Apr;33(2):105-12
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8. Tolan DR. Molecular basis of hereditary fructose intolerance: Mutations and polymorphisms in the human aldolase B gene. Hum. Mutat. 1995;6:210–218.
9. James CL, Rellos P, Ali M, Heeley AF, Cox TM. Neonatal screening for hereditary fructose intolerance: frequency of the most common mutant aldolase B allele (A149P) in the British population. J Med Genet. 1996;33(10):837-41.
10. Ferri L, Caciotti A, Cavicchi C, Rigoldi M, et al. Integration of PCR-sequencing analysis with multiplex ligation-dependent probe amplification for diagnosis of hereditary fructose intolerance. JIMD Rep. 2012;6:31-7.
11. Coffee EM, Yerkes L, Ewen EP, Zee T, Tolan DR. Increased prevalence of mutant null alleles that cause hereditary fructose intolerance in the American population. J Inherit Metab Dis. 2010 Feb;33(1):33-42.
12. Morris RC Jr. An experimental renal acidification defect in patients with hereditary fructose intolerance. J Clin Invest. 1968;47:1648–63.