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.
De Toni-Fanconi syndrome
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, or cadmium
- Lowe syndrome, a rare genetic disorder of the eyes, brain, and kidneys
- Wilson 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
- Passing large amounts of urine, which can lead to dehydration
- Bone pain
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:
- Dehydration due to excess urination
- Growth failure
- Type 2 renal tubular acidosis
Many different diseases can cause Fanconi syndrome. The underlying cause and its symptoms should be treated as appropriate.
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.
Kliegman RM, Stanton BF, St Geme JW, Schor NF. Electrolyte and acid-base disorders. In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 55.
Mount DB. Disorders of potassium balance. 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 18.
Seifter JL. Acid-base disorders. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 118.
Reviewed By: Walead Latif, MD, Nephrologist and Clinical Associate Professor, Rutgers Medical School, Newark, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.