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# Hereditary fructose intolerance

In hereditary fructose intolerance, fruit, sugar or honey cause vomiting, hypoglycaemia and liver and kidney damage.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Liver](https://durgical.com/en/anatomy/liver/)
- [Kidneys](https://durgical.com/en/anatomy/kidney/)
- [Jejunum](https://durgical.com/en/anatomy/jejunum/)
- [Pancreas](https://durgical.com/en/anatomy/pancreas/)

## In biochemistry

- [Fructose metabolism: Step 4 · Aldolase B](https://durgical.com/en/biochemistry/pathways/fructose-metabolism/#paso-4)
- [Fructose-1,6-bisphosphatase (FBPase-1)](https://durgical.com/en/biochemistry/enzymes/fructose-1-6-bisphosphatase/)
- [Aldolase B](https://durgical.com/en/biochemistry/enzymes/aldolase-b/)
- [Fructose](https://durgical.com/en/biochemistry/molecules/fructose/)

## In physiology

- [Carbohydrate digestion and absorption](https://durgical.com/en/physiology/carbohydrate-digestion-and-absorption/)

## What it is

Inborn error of metabolism caused by lack of aldolase B (ALDOB gene). Symptoms start when the baby receives fructose, sucrose or sorbitol, usually with complementary feeding.

## Who gets it

About 1 in 20,000 to 30,000 people worldwide.

## Causes

- Autosomal recessive inheritance: ALDOB gene variants (A149P commonest in Europe)

## Risk factors

- Carrier parents or affected siblings
- Exposure to fructose, sucrose or sorbitol (trigger)

## Pathophysiology

Fructokinase keeps turning fructose into fructose 1-phosphate, but without aldolase B it accumulates in liver, kidney and intestine. It traps phosphate: ATP falls, nucleotides are broken down (high uric acid) and glycogen phosphorylase and gluconeogenesis are halted, so hypoglycaemia appears. ATP shortage damages hepatocytes and the proximal tubule (Fanconi syndrome).

## Symptoms and signs

- Vomiting, abdominal pain and sweating after fruit, juice or sugary foods
- Hypoglycaemia with drowsiness or seizures
- Failure to thrive and jaundice
- Spontaneous aversion to sweets; teeth without caries

## Red flags

- Infant with vomiting, lethargy and jaundice after starting fruit or juice
- Bleeding or signs of liver failure

## Diagnosis

**Clinical**
Symptoms that appear after fructose and disappear when it is removed; aversion to sweet foods.

**Tests**
During exposure: hypoglycaemia, hypophosphataemia, high uric acid, raised transaminases, abnormal clotting and signs of tubulopathy in urine. ALDOB gene testing. Fructose loading tests are no longer recommended because of their risk.

**Imaging**
Abdominal ultrasound: large or fatty [liver](https://durgical.com/en/anatomy/liver/); sometimes nephrocalcinosis.

## Treatment

**Lifestyle**
Lifelong removal of fructose, sucrose and sorbitol from the diet, with dietitian support

**Medical**
Check that medicines and syrups contain no sucrose, fructose or sorbitol; vitamin supplements because of the fruit-free diet

**Acute**
Intravenous glucose and removal of fructose in a crisis

**Follow-up**
Monitoring of growth, liver and [kidney](https://durgical.com/en/anatomy/kidney/)

## Complications

- Acute liver failure
- Renal Fanconi syndrome
- Fatty liver
- Death if fructose or sorbitol infusions are given

## Prognosis

With a strict diet the outlook is excellent and growth is normal.

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzyme is missing in hereditary fructose intolerance?

Aldolase B of liver, kidney and intestine.

## Why does the patient with hereditary fructose intolerance become hypoglycaemic?

Fructose 1-phosphate traps phosphate and halts glycogen phosphorylase and gluconeogenesis.

## Which dental finding is typical in these patients?

They have almost no caries, because they avoid sugar.

## Which component of syrups and infusions is dangerous besides fructose?

Sorbitol, which the body turns into fructose, and sucrose.

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## Related conditions

- [Essential fructosuria](https://durgical.com/en/conditions/essential-fructosuria/)
- [Acute kidney injury](https://durgical.com/en/conditions/acute-kidney-injury/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)
- [Dental caries](https://durgical.com/en/conditions/dental-caries/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Hereditary fructose intolerance: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/hereditary-fructose-intolerance/) (MedlinePlus, US National Library of Medicine, 2026); [Hereditary fructose intolerance: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000359.htm) (MedlinePlus, US National Library of Medicine, 2026); [ALDOB gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/aldob/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Source: https://durgical.com/en/conditions/hereditary-fructose-intolerance/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/hereditary-fructose-intolerance/