Health Encyclopedia

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 syndrome

Causes, incidence, and risk factors

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:

Cystine (cystinosis)
Fructose (fructose intolerance)
Galactose (galactosemia)
Glycogen (glycogen storage disease)

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

Other causes in children include:

Exposure to heavy metals such as lead, mercury, and cadmium
Lowe's disease, a rare genetic disorder of the eyes, brain, and kidneys
Wilson's disease

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

Certain medications, including azathioprine, cidofovir, gentamicin, and tetracycline
Kidney transplant
Light chain deposition disease
Multiple myeloma
Primary amyloidosis

Symptoms

Passing large amounts of urine, which can lead to dehydration
Bone pain
Weakness

Signs and tests

Laboratory tests may show that excess amounts of the following substances may be lost in the urine:

Amino acids
Bicarbonate
Glucose
Magnesium
Phosphate
Potassium
Sodium
Uric acid

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

Dehydration due to excess urination
Growth failure
Osteomalacia
Rickets
Type 2 renal tubular acidosis

Treatment

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

Expectations (prognosis)

The prognosis depends on the underlying disease.

Calling your health care provider

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

References

Seifter JL. Potassium disorders. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 118.

Review Date:11/10/2008
Reviewed By:David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and James R. Mason, MD, Oncologist, Director, Blood and Marrow Transplantation Program and Stem Cell Processing Lab, Scripps Clinic, Torrey Pines, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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