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# Tarui disease (muscle phosphofructokinase deficiency)

Tarui disease is an inherited disorder in which muscles cannot burn sugar: exercise brings cramps and dark urine.

Updated 2026-10-31

## Structures involved

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

- [Vastus lateralis](https://durgical.com/en/anatomy/vastus-lateralis-muscle/)
- [Biceps femoris (long head)](https://durgical.com/en/anatomy/long-head-of-biceps-femoris/)
- [Vastus medialis](https://durgical.com/en/anatomy/vastus-medialis-muscle/)
- [Femur](https://durgical.com/en/anatomy/femur/)

## In biochemistry

- [Glycolysis: Step 3 · Phosphofructokinase-1 (PFK-1)](https://durgical.com/en/biochemistry/pathways/glycolysis/#paso-3)
- [Fructose 1,6-bisphosphate](https://durgical.com/en/biochemistry/molecules/fructose-1-6-bisphosphate/)
- [Phosphofructokinase-1 (PFK-1)](https://durgical.com/en/biochemistry/enzymes/phosphofructokinase-1/)
- [Exercise metabolism](https://durgical.com/en/biochemistry/topics/exercise-metabolism/)

## What it is

Glycogen storage disease type VII: muscle phosphofructokinase is missing (PFKM gene). Muscle cannot use glucose or glycogen for energy during effort.

## Who gets it

Very rare; described worldwide, with most published cases in Japanese and Ashkenazi Jewish families.

## Causes

- Autosomal recessive inheritance, PFKM variants

## Risk factors

- Affected siblings or carrier parents

## Pathophysiology

Without muscle PFK-1, glycolysis stops at fructose 6-phosphate: glycogen builds up and muscle relies on fatty acids. Red cells lose half their activity (the M subunit), causing mild hemolysis; nucleotide breakdown raises uric acid.

## Classification

- Classic form: exercise intolerance from childhood
- Late-onset form: progressive weakness in adults
- Severe infantile form (rare)

## Symptoms and signs

- Cramps and muscle pain with hard exercise
- Dark urine after effort (myoglobinuria)
- Fatigue that worsens after a carbohydrate-rich meal
- Mild jaundice from hemolysis
- Gout or high uric acid

## Red flags

- Dark urine with little urine or severe pain after exercise (rhabdomyolysis with [kidney](https://durgical.com/en/anatomy/kidney/) -failure risk)

## Diagnosis

**Clinical**
Exercise intolerance with cramps and myoglobinuria, plus compensated hemolysis; worse after carbohydrates.

**Tests**
High CK; raised reticulocytes and bilirubin; high uric acid. On forearm exercise testing lactate fails to rise while ammonia does. Muscle biopsy with stored glycogen and low PFK activity; PFKM gene testing.

**Imaging**
Imaging is not needed for diagnosis; muscle MRI may show fatty change in late forms.

## Treatment

**Lifestyle**
Avoid intense or long exercise; regular, moderate aerobic exercise

**Lifestyle**
Avoid carbohydrate-heavy meals before exercise

**Acute**
Urgent intravenous fluids if rhabdomyolysis occurs

**Medical**
Treatment of high uric acid or gout

## Complications

- Rhabdomyolysis with acute kidney injury
- Gout
- Gallstones from hemolysis

## Test yourself

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

## Which glycolysis step fails in Tarui disease?

Step 3, muscle phosphofructokinase-1.

## What does forearm exercise testing show?

Lactate does not rise while ammonia does.

## Why does a carbohydrate-rich meal make symptoms worse?

Insulin lowers free fatty acids and ketones, the only fuel the affected muscle can use.

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## Related conditions

- [Gout](https://durgical.com/en/conditions/gout/)

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

Sources: [Glycogen storage disease type VII: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/glycogen-storage-disease-type-vii/) (MedlinePlus, US National Library of Medicine, 2026); [PFKM gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/pfkm/) (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/tarui-disease/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/tarui-disease/