Definition
Fanconi syndrome is a pathological condition characterized by multiple defects in proximal tubular reabsorption, involving glycosuria, phosphaturia, generalized aminoaciduria and loss of bicarbonate.
Fanconi syndrome can be hereditary or acquired. The hereditary form is often accompanied by other genetic pathologies, such as cystinosis and Wilson's disease, which are transmitted by variable models. The acquired form can instead be caused by various nephrotoxic drugs, including some chemotherapeutic drugs (eg ifosfamide and streptozocin), antiretrovirals (eg didanosine and cidofovir) and expired tetracyclines. Acquired Fanconi syndrome can also occur after a renal transplant and in patients with multiple myeloma, amyloidosis, vitamin D deficiency, intoxication from heavy metals or other chemicals.
In Fanconi syndrome, several defects of the proximal tubule transport function occur, such as impaired glucose, phosphate, amino acid, bicarbonate, uric acid, water, potassium and sodium reabsorption. The pathophysiological alteration underlying these alterations is unknown, but a concomitant mitochondrial disorder may be present.
Most common symptoms and signs *
- Kidney stones
- Night Cramps
- Bone pain
- Bone fractures
- Glycosuria
- Hypophosphatemia
- Hypokalemia
- Polyuria
- Proteinuria
- Growth delay
- Intense thirst
Further indications
In childhood, hereditary Fanconi syndrome causes growth-stagnation, proximal tubular acidosis, hypokalemia, polyuria and polydipsia. Furthermore, low serum phosphate levels cause rickets, a condition worsened by reduced conversion of vitamin D in its active form to the proximal tubules.
In the form associated with cystinosis, a developmental deficit and a depigmentation of the retina is frequent; an interstitial nephritis develops which leads to a progressive renal failure. The latter can be lethal before adolescence.
In acquired Fanconi syndrome, adults have osteomalacia and muscle weakness. Furthermore, laboratory alterations related to proximal renal tubular acidosis, hypophosphataemia and hypokalemia are present.
Diagnosis arises with the finding of alterations in renal function, in particular glycosuria, phosphaturia and aminoaciduria.
Besides providing for the removal of the nephrotoxic agent (where necessary) and adopting measures aimed at renal failure, there is no specific treatment.
Acidosis can be decreased by administering tablets or sodium bicarbonate solutions; furthermore, potassium supplementation may be necessary.
