What is the treatment for Fanconi syndrome?

Treatment of Fanconi Syndrome

The treatment of Fanconi syndrome requires immediate fluid and electrolyte replacement combined with aggressive management of the underlying cause, with cysteamine therapy for cystinosis and NTBC for tyrosinemia type I being disease-specific interventions that can reverse the tubulopathy.

Immediate Supportive Management

Fluid and Electrolyte Replacement

• Administer intravenous 10% dextrose/normal saline solutions at 1.5-2.0 times maintenance rate to maintain normoglycemia and correct dehydration 1
• Replace lost electrolytes including potassium, phosphate, and bicarbonate to address the global proximal tubular dysfunction 1, 2
• Monitor for hypokalemia, sodium wasting, and metabolic acidosis which are characteristic features 2

Specific Electrolyte Corrections

• Initiate potassium citrate for type II renal tubular acidosis 3
• Administer calcitriol for hypophosphatemia to prevent bone demineralization 3, 4
• Address phosphate wasting aggressively as this leads to the most serious complication of bone demineralization 4

Disease-Specific Treatment

Cystinosis-Related Fanconi Syndrome

• Initiate cysteamine therapy immediately upon diagnosis confirmation at 1 mg/kg/day, increasing to 2 mg/kg/day if no improvement is seen 1
• Implement nutritional management with restriction of phenylalanine and tyrosine intake 1
• Use medical foods devoid of phenylalanine and tyrosine while ensuring adequate protein intake (higher than normal requirements) 1

Tyrosinemia Type I-Associated Fanconi Syndrome

• NTBC (nitisinone) treatment with dietary restriction of phenylalanine/tyrosine reverses or prevents tubulopathy in nearly all cases within weeks 1
• This represents the most effective disease-specific intervention when tyrosinemia is the underlying cause 1
• Continue periodic screening for renal disease even after liver transplantation, as succinylacetone excretion persists post-transplant 1

Drug or Toxin-Induced Fanconi Syndrome

• Immediately discontinue the offending agent (cisplatin, ifosfamide, tenofovir, sodium valproate, aminoglycosides, deferasirox, or supplements like red yeast rice) 5, 4
• Consider corticosteroid therapy (oral prednisolone) in cases of severe proximal tubular injury 5
• Substantial recovery of proximal tubular function can occur after withdrawal, though this may take months and chronic damage may persist 4

Iron Overload-Related Fanconi Syndrome

• Initiate deferoxamine therapy for hemosiderosis-induced proximal tubular dysfunction 3
• This is particularly relevant in patients with paroxysmal nocturnal hemoglobinuria or chronic transfusion requirements 3

Monitoring and Follow-Up

Laboratory Surveillance

• Perform regular assessment of renal function through blood and urine tests, including electrolytes, glucose, amino acids, and phosphate 1
• Monitor for glucosuria, phosphaturia, generalized aminoaciduria, and metabolic acidosis 2
• Note that estimated glomerular filtration rate and urine albumin/creatinine ratio are not sensitive markers of proximal tubular toxicity 4

Imaging Studies

• Obtain renal ultrasound to monitor kidney structure 1
• Perform bone X-rays and densitometry to assess for rachitic changes from hypophosphatemia 1

Critical Pitfalls to Avoid

• Do not rely on standard kidney function tests alone—they miss proximal tubular toxicity; use specific markers like urinary phosphate, glucose, and amino acids 4
• Do not overlook exogenous causes—take a thorough history including prescription medications, over-the-counter drugs, and dietary supplements 5
• Do not delay treatment of the underlying cause—early intervention with disease-specific therapy (cysteamine for cystinosis, NTBC for tyrosinemia) can reverse tubulopathy 1
• Do not underestimate bone complications—phosphate wasting leads to serious bone demineralization requiring aggressive replacement 4