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Definition of Fanconi’s Syndrome
Fanconi’s Syndrome – a dysfunction of the kidneys in which the renal tubules do not function properly, resulting in a constellation of diverse symptoms. The renal tubule, a structure of the kidney’s filtering mechanism within the nephron, filters many substances from the blood to retain those the body needs and excrete those the body does not need.
In Fanconi’s syndrome, the renal tubule excretes into the urine numerous vital substances it should retain in the blood. Among these substances are glucose, uric acid, calcium, magnesium, potassium, phosphate, and amino acids. The renal tubule also excretes excessive water into the urine.
Causes and Symptoms
Numerous genetic disorders cause Fanconi’s syndrome. Among the most common are metabolic conditions that affect the body’s ability to use or store substances such as cystine, glycogen, fructose, and tyrosine. Heavy-metal poisoning, such as from lead or mercury, and drug toxicity account for most acquired Fanconi’s syndrome. Conditions such as amyloidosis, in which protein deposits accumulate in organs such as the kidneys, also can damage the renal tubules to cause Fanconi’s syndrome. The syndrome occasionally develops in people who undergo kidney transplantation.
Equally numerous symptoms can suggest Fanconi’s syndrome and may appear initially to be unrelated. In children the most common symptoms are stunted growth, bone deformities similar to those which occur in rickets, and muscle weakness. In adults, the most common symptoms are spontaneous fracture, electrolyte imbalance, and serum acidosis (increased acidity of the blood). General symptoms sometimes present in children or adults include excessive thirst and urination, constipation, and dehydration. Blood and urine tests identify the depletions and excesses of the substances the renal tubules are failing to reabsorb.
Treatment targets the underlying cause when doctors can identify it and the resulting conditions when the underlying cause remains unknown (idiopathic Fanconi’s syndrome). Doctors can treat many genetic disorders of metabolism from early childhood, forestalling or preventing complications such as Fanconi’s syndrome. With appropriate treatment kidney function can return to normal. Untreated Fanconi’s syndrome can progress to end-stage renal disease (esrd), requiring long-term renal dialysis or kidney transplantation.
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