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The information contained on this page is provided as general health information and is not intended to substitute as medical advice and direction from your physician or health care provider. Please direct any questions related to your health care provider. In an emergency, call 9-1-1 or go to the nearest emergency center.


Fanconi syndrome

Definition

Fanconi syndrome is a disorder of the kidney tubes in which certain substances normally absorbed into the bloodstream by the kidneys are released into the urine instead.

Alternative Names

De Toni-Fanconi-Debré syndrome

Causes

Fanconi syndrome can be caused by faulty genes, or it may result later in life due to kidney damage. Sometimes the cause of Fanconi syndrome is unknown.

Common causes of Fanconi syndrome in children are genetic defects that affect the body's ability to break down certain compounds such as:

Cystinosis is the most common cause of Fanconi syndrome in children.

Other causes in children include:

  • Exposure to heavy metals such as lead, mercury, or cadmium
  • Lowe syndrome, a rare genetic disorder of the eyes, brain, and kidneys
  • Wilson disease
  • Dent disease, a rare genetic disorder of the kidneys

In adults, Fanconi syndrome can be caused by various things that damage the kidneys, including:

Symptoms

Symptoms include:

  • Passing large amounts of urine, which can lead to dehydration
  • Excessive thirst
  • Severe bone pain
  • Fractures due to bone weakness
  • Muscle weakness

Exams and Tests

Laboratory tests may show that too much of the following substances may be lost in the urine:

Loss of these substances can lead to a variety of problems. Further tests and a physical exam may show signs of:

Treatment

Many different diseases can cause Fanconi syndrome. The underlying cause and its symptoms should be treated as appropriate.

Outlook (Prognosis)

The prognosis depends on the underlying disease.

When to Contact a Medical Professional

Call your health care provider if you have dehydration or muscle weakness.

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Kidney anatomy

References

Bonnardeaux A, Bichet DG. Inherited disorders of the renal tubule. In: Skorecki K, Chertow GM, Marsden PA, Taal MW, Yu ASL, eds. Brenner and Rector's The Kidney. 10th ed. Philadelphia, PA: Elsevier; 2016:chap 45.

Foreman JW. Fanconi syndrome and other proximal tubule disorders. In: Johnson RJ, Feehally J, Floege J, eds. Comprehensive Clinical Nephrology. 5th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 50.