Overview
Fanconi’s syndrome (FS) describes dysfunction of resorption in the proximal renal tubules of the kidney. It leads to the urinary loss of substances that would normally be reabsorbed, including glucose, amino acids, phosphate, and bicarbonate.
It is associated with type 2 renal tubular acidosis, which describes the failure of bicarbonate reabsorption in the proximal renal tubules.
Epidemiology
- The causes of Fanconi syndrome are generally rare
Causes
Inherited causes include:
- Idiopathic
- Cystinosis – most common in children
- Wilson’s disease
Acquired causes include:
- Sjögren’s syndrome
- Rejected renal transplants
- Multiple myeloma
- Intrinsic kidney diseases (e.g. acute tubular necrosis and interstitial nephritis)
- Hyperparathyroidism
- Some drugs (e.g. aminoglycoside antibiotics)
- Some toxins (e.g. glue sniffing and heavy metals)
Presentation
Patients may present with:
- Polyuria
- Polydipsia
- Dehydration
- Rickets/osteomalacia – due to excess urinary calcium loss secondary to impaired urine acidification. Calcium tends to deposit at higher pHs
- Failure to thrive
Investigations
Investigations may show:
- Urinalysis:
- Proteinuria
- Amino acids, glucose, phosphates, and bicarbonate
- Urea and electrolytes (U&Es):
- Arterial/venous blood gas:
- Hyperchloraemic metabolic acidosis
Management
Management involves treating the underlying cause and replacing the substances lost in the urine.
