Fanconi Syndrome

Fanconi Syndrome is a dysfunction of kidney tubules that can be hazardous for young and old alike. Read on to know all about its causes, symptoms, diagnosis and cure for this condition.

What is Fanconi Syndrome?

Fanconi Syndrome, or Fanconi’s Syndrome, is a rare disorder which affects the proximal tubules of the kidney and does not allow the re-absorption of essential minerals and glucose into blood. Rather, such important nutrients get wasted through urine. After the fluid is filtered, the tubule is supposed to process it but it fails to do that. It can manifest in varied forms and cause a range of complications if not checked on time. It gets its name from the Swiss pediatrician Guido Fanconi, who contributed to the explanation of the disease.

It affects humans as well as dogs, although cats are also affected sometimes.

Fanconi Syndrome Prevalence

This disease has an uncommon occurrence, occurring irregularly as it is evident from the reports. Its inherited forms appear early in children. Caucasian children seem to be at risk of having glycosuria and renal acidoses due to this disease. Accurate information, regarding the prevalence of this disease in any specific population in its acquired forms, is unavailable.

Fanconi Syndrome in Dogs

The occurrence of this disease is not restricted to humans alone. Dogs are equally prone to it. Basenji is the breed that is worst affected by the disorder. It also affects other breeds like Schnauzers and Norwegian Elkhounds.

Due to the onset of this condition, functions of kidney tubules get impaired. Instead of reabsorbing minerals, sugars and essential vitamins to be used in the body, it gets wasted through urine. The loss of solutes causes electrolyte imbalance and dehydration in dogs apart from some more problems.

In Basenjis, the disease is hereditary. In some cases, however, it has been found to be acquired. Differentiating between acquired and genetic cases might not be easy.

In the past, chicken jerky treats for dogs were causing serious concern amongst pet owners. The FDA had issued warnings against it for causing Fanconi-like symptoms in them.

Causes of Fanconi’s Syndrome

In general, this disorder affects the functions of the proximal tubules of the kidney instead of a particular channel. It is different from other tubular conditions like Hartnup disease. It can be caused due to a host of underlying disorders. However, the exact cause of this disease may also remain unknown at times. Genetic link has been established in context of this disorder, when it occurs in children. It can be primary or secondary, on the basis of the process of getting it, through parents or other factors like:

Genetic Defect

In children, it may occur due to genetic factors from Cystinosis. Due to mutation in the gene CTNS, functions of cystinosin becomes faulty. It creates intralysosomal accumulation of cystine, which then leads to severe tubular dysfunction of the kidney in the infant. This condition can be found to exist with other hereditary diseases like Lowe Syndrome and Wilson’s disease.

Drugs

This disease can be acquired by adults, due to certain drug formualtions. Drugs which cause mitochondrial dysfunction have full potential to lead to this disease. Chemotherapy drugs or expired tetracycline antibiotics can be potent causes. Gentamicin, cidofovir, and azathioprine are a few other factors. This condition may also arise as side effects of taking certain medicines or due to having them after expiration. It may become pertinent in patients already suffering from kidney damage. Adefovir and tenofovir drugs can cause HIV patients to get this syndrome.

Multiple myeloma and renal transplants are other factors which may lead to acquisition of this disease. Platinum, mercury, lead and other heavy metals are other agents which cause the acquired form of this disease.

Fanconi Syndrome Symptoms

Certain signs and symptoms start showing when amino acids, phosphates, glucose or other important substances do not get absorbed into the blood. The signs of Proximal renal tubular acidoses include:

• Heightened thirst
• Excess Urination
• Dehydration
• Acidoses
• Retardation of growth
• Hypo-phosphatemia, which manifests as osteomalacia in grownups and rickets in children.
• Hypokalemia
• Hyperchlorema

In case of general proximal tubular dysfunction, glucose, protein and phosphates are found in urine.

Fanconi Syndrome Symptoms in Dogs

Some of these common symptoms are noted in dogs:

• Excessive thirst leading to overconsumption of fluids.
• Excess urinating
• Loss of weight

In severe cases, the following problems can be caused:

• Metabolic acidoses
• Electrolyte imbalances

Fanconi Syndrome Diagnosis

Bicarbonate wasting, accompanied by Hyperchloraemic metabolic acidosis, may signal the need for testing the patient for Fanconi’s syndrome. Evaluation is also done when a patient is found to be affected by a certain medical condition related to this syndrome.

To diagnose this disease, a series of tests have to be conducted to assess the excess loss of substances like phosphate and glucose, through urine. Tests are basically determined after consulting the medical history of a patient and performing a thorough physical checkup. Laboratory tests are conducted for checking the levels of amino acids, phosphate, uric acid, sodium, bicarbonate, potassium etc. Blood and urine tests are done for clinical diagnosis.

There seems to be no significance of radiological evaluation in this case. In very rare cases, rickets caused due to mineral wasting may be reported.

Fanconi Syndrome Treatment

The treatment of this syndrome is based on the correct diagnosis of the underlying disease which is primarily responsible for it. Substances that are meant to be utilized by the bloodstream get lost into the urine. Treatment plan basically centers on the replacement of these lost substances comprising electrolytes and fluids that are essential to the body.

Know about some of the ways by which the disorder is treated:

• To normalize levels of serum phosphate, it should be given to the patient in small dosages. To avert symptoms like gastric, the amount is subsequently increased over time.
• IV solutions or oral intake is advised to check dehydration in these patients, which results due to polyuria.
• In such conditions, diuretics are advised to control volume expansion though it leads to loss of potassium. In order to check this loss, supplement of potassium including potassium bicarbonate, acetate and citrate, are given.
• Liver failure may occur due to Wilson disease, for which a liver transplant can be done. It is usually successful in managing the abnormalities resulting in the renal tubes.
• To cure metabolic acidoses, sodium bicarbonate is administered in right doses. Alkali helps in rectifying this problem.
• Replacement of uric acid, amino acids or glucose is not important as they seldom lead to symptoms.
• Enzyme insufficiency also results in this syndrome. Proper diet should be consumed by these patients. Those with Wilson disease should be fed with diet having less copper.
• If cystinosis results in kidney failure, kidney transplant can be done.
• To improve strength of the muscles, carinitine supplements are sometimes administered. However, they may not offer satisfactory results all the time.

Fanconi Syndrome Treatment in Dogs

No definite treatment for this disease exists as yet. Management is the key to endow a healthy life to the affected dog. Dehydration can be checked by making fresh water available to it. To maintain the solute levels, some supplements can also be given. Routine urine checkup for Basenjis can be done to ensure early detection which minimizes chances of kidney impairment.

Fanconi Syndrome Diet and Activities

As already indicated, deficiencies in enzyme often causes different forms of this disease. These enzymes are entrusted with the metabolism of fructose, galactose, tyrosine, phenylalanine and other nutrients. Symptoms associated with the kidneys usually go away when these substances are excluded from the diet. No restrictions have been put on the activities of the patients with Fancony syndrome. Due to the risk of organ failure, muscular strength can be severely affected which certainly restricts stressful physical activities.

Fanconi Syndrome Life Expectancy

The death rate associated to this condition is related with the metabolic abnormalities which can be caused in the patients. It usually does not affect the normal lifespan of an individual if serious kidney failures have not taken place. Studies show that dogs with idiopathic form of this syndrome can have normal lifespan.

Fanconi Syndrome vs Fanconi Anemia

Fanconi anemia (FA) should be distinguished from Fanconi syndrome as both are separate diseases. FA is rare disorder of the blood that causes failure of the bone marrow. Whereas Fanconi’s syndrome is related with the kidneys and children are more susceptible to it.

Fanconi Syndrome vs. Fanconi Bickel Syndrome

Fanconi Bickel syndrome results due to mutation in the GLUT2 gene which leads to carbohydrate metabolism. This rare disease causes kidneys and liver to enlarge by the second year of life, giving rise to life-threatening consequences.

Fanconi Syndrome Prognosis

The prognosis of this syndrome seems to be reasonable. However, the outcome depends on the underlying disease. Along with the treatment plan, the time of diagnosis plays a role in influencing the outcome to a great extent. If it is an acquired form, it will subside within a specific period. However, the inherited ones can lead to organ failures and pose a lot of problems related to growth. Kidney failure, neurologic disorders, visual impairment, ovarian dysfunction, mental retardation and hypotonia are some of the ailments which can be caused due to late diagnosis and enhanced severity. Naturally, it is important to detect and treat the syndrome on an early basis.

References:

http://en.wikipedia.org/wiki/Fanconi_syndrome

http://www.fanconisyndrome.net/Fanconi-Syndrome-Causes.html

http://www.uspharmacist.com/content/d/health_systems/c/28622/

http://www.healthline.com/galecontent/fanconi-bickel-syndrome