Fanconi syndrome is a rare disorder of tubule function that results in excess amounts of glucose, bicarbonate, phosphates (phosphorus salts), uric acid, potassium, sodium, and certain amino acids being excreted in the urine.
Fanconi syndrome may be hereditary or may be caused by exposure to certain drugs (including some chemotherapy and antiretroviral drugs), exposure to heavy metals or other chemicals, vitamin D deficiency, kidney transplantation, multiple myeloma, or amyloidosis. Fanconi syndrome usually occurs with another hereditary disorder, such as cystinosis.
Symptoms and Diagnosis
In hereditary Fanconi syndrome, symptoms usually begin during infancy. A child with Fanconi syndrome may excrete a large amount of urine and eventually slowed growth. In adults, symptoms may not develop until the disorder has been present for some time. The most common symptoms in adults include weakness and bone pain.
The symptoms and a test that shows abnormalities in the blood (such as a high level of acid) or urine (such as a high level of glucose) may lead a doctor to suspect Fanconi syndrome. The diagnosis is confirmed when high levels of glucose, bicarbonate, phosphates, uric acid, potassium, and sodium are detected in the urine. Most often, some damage to bones or kidney tissue has occurred before the diagnosis is made.
Fanconi syndrome cannot be cured, but it can be controlled with proper treatment. Effective treatment can keep the damage to bones and kidney tissue from getting worse and in some cases correct it. The high acid level of the blood (acidosis) may be neutralized by drinking sodium bicarbonate. People with low potassium levels in the blood may need to take potassium supplements by mouth. Bone disease requires treatment with phosphates and vitamin D supplements given by mouth. Kidney transplantation may be lifesaving if a child with the disorder develops kidney failure.
Last full review/revision July 2013 by James I. McMillan, MD