Fanconi syndrome (FS) is a rare disorder that affects the filtering tubes (proximal tubules) of the kidney. It’s named after Swiss pediatrician Guido Fanconi, who described the disorder in the 1930s. Fanconi also first described a rare anemia, Fanconi anemia. This is an entirely different condition unrelated to FS.
Causes of Fanconi Syndrome
Cystinosis is the most common cause of FS.
It’s a rare inherited disease. In cystinosis, the amino acid cystine accumulates throughout the body.
This leads to delayed growth and a series of disorders, such as bone deformities.
The most common and severe form of cystinosis occurs in infants and involves FS.
Other inherited metabolic diseases that can be involved with FS include:
Inherited fructose intolerance
Symptoms of Fanconi Syndrome
Failure to thrive
Low muscle tone
Diagnosis of Fanconi Syndrome
Infants and children with inherited Fanconi Syndrome
Usually the symptoms of FS appear early on in infancy and childhood.
Parents may notice excessive thirst or slower than normal growth. Children may have rickets or kidney problems.
Your child’s doctor will order blood and urine tests to check for abnormalities, such as high levels of glucose, phosphates, or amino acids, and to rule out other possibilities.
They may also check for cystinosis by looking at the child’s cornea with a slit lamp examination.
This is because cystinosis affects the eyes.
Acquired Fanconi Syndrome
Your doctor will ask for your or your child’s medical history, including any drugs you or your child is taking, other diseases present, or occupational exposures.
They’ll also order blood and urine tests.
In acquired FS, you may not notice the symptoms right away.
Bones and kidneys may be damaged by the time a diagnosis is made.
Treatment of Fanconi Syndrome
A high-calorie diet is recommended to maintain proper growth.
If the child’s bones are malformed, physical therapists and orthopedic specialists may be called in.
The presence of other genetic diseases may require additional treatment.
For example, a low-copper diet is recommended for people with Wilson’s disease.
In cystinosis, FS is resolved with a successful kidney transplant following renal failure.
This is considered a treatment for the underlying disease, rather than a treatment for FS.
For children with inherited FS, the first line of treatment is to replace the essential substances that are being eliminated in excess by the damaged kidneys.
Replacement of these substances may be by mouth or by infusion. This includes replacement of:
Water (when the child is dehydrated)
Other minerals and nutrients