Causes and Symptoms of Fanconi Syndrome

Fanconi's Syndrome can be caused by a variety of genetic defects and by certain environmental assaults.

What Can Cause Fanconi Syndrome

The genetic diseases known to give rise to Fanconi's Syndrome are cystinosis (the most common cause in children), galatosemia, glycogen storage disease, hereditary fructose intolerance , Lowe Syndrome, Wilson Disease, tyrosinemia, medullary cystic disease, vitamin D dependency, and familial idopathic Fanconi's Syndrome.
Environmental assaults that cause Fanconi's Syndrome include:

• Exposure to heavy metals (like cadmium, lead, mercury,platinum, uranium)
• Certain drugs (like outdated tetracycline and gentamicin)
• Other substances (like Lysol, paraquat, toluene, the amino acid lysine taken as a nutritional supplement
• Kidney transplantation

Symptoms of Fanconi Syndrome

Fanconi's syndrome symptoms related directly to impaired absorption include:

• Excessive urine production and urination
• Excessive thirst; dehydration; constipation; anorexia nervosa; vomiting
• Elevated levels of glucose, phosphate, calcium, uric acid, amino acids, and protein (especially beta2-microglobulin and lysozyme) in the urine
• Elevated levels of chloride and decreased levels of phosphate and calcium in the blood; and excessively acidic blood

The most noticeable indirect consequences of impaired reabsorption are the bone diseases, rickets and osteomalacia. Rickets affects children and is associated with bone deformities, failure to grow, and difficulty walking. If a person acquires Fanconi's syndrome as an adult, the bone disease is termed osteomalacia and is accompanied by severe bone pain and spontaneous fractures. Unlike rickets due to malnutrition, these diseases cannot be reversed with vitamin D. Muscle weakness and occasional paralysis are other indirect consequences of the ineffective reabsorption.

Diagnosis and Treatment of Fanconi Syndrome

Diagnosis of Fanconi's syndrome can be made by urine and blood tests. It is also important to find the underlying cause to decide on the best treatment. Other symptoms specific to a particular patient will point to other useful diagnostic tests. For example, high levels of blood galactose in conjunction with symptoms of Fanconi's syndrome indicate the patient is suffering from galactosemia, while high blood levels of cadmium indicate the patient is suffering from cadmium poisoning.

Treatment of Fanconi Syndrome

Fanconi's syndrome is best treated by attacking the underlying cause whenever possible. For example, when cystinosis is treated with the drug cysteamine to lower cystine levels in the body or Wilson disease is treated with penicillamine to lower the levels of copper, accompanying symptoms of Fanconi's syndrome will subside. If the patient has acquired the disease from a heavy metal or another toxic agent, all contact with the toxic agent should stop; the condition will then likely disappear.
Nevertheless, additional treatment will be necessary either when it's not possible to treat the underlying cause or while waiting for the kidneys to resume normal function. This is done by restricting sodium chloride (table salt), giving antacids to counteract the excessive acidity of the blood, and supplying potassium supplements.

Kidney transplant is the treatment of last resort, used for patients whose kidneys have failed.

Prognosis

Fanconi's syndrome can be reversible. Fanconi's syndrome caused by kidney transplantation usually reverses itself within the first year after transplant surgery. When caused by a toxin in the environment, Fanconi's syndrome generally can be reversed by removing the causative agent from the patient's environment. If it is caused by a genetic disease, it can usually be reversed by treating the disease. However, if Fanconi's syndrome is not treated or if treatment is unsuccessful, the kidneys can fail.

Fanconi Syndrome Prevention

Fanconi's syndrome caused secondarily by the genetic diseases galactosemia, glycogen storage disease, hereditary fructose intolerance, and tyrosinemia is prevented by appropriate dietary restrictions to treat the genetic disease, starting in infancy.
Fanconi's syndrome caused by heavy metals and other toxins can be prevented by avoiding these substances. s

Source: Gale Encyclopedia of Medicine, Published December, 2002 by the Gale Group
The Essay Author is Lorraine Lica PhD.