Fanconi syndrome
| Fanconi syndrome | |
|---|---|
| Specialty | Nephrology, endocrinology  |
Fanconi syndrome (also known as Fanconi's syndrome) is a disease of the proximal renal tubules[1] of the kidney in which glucose, amino acids, uric acid, phosphate and bicarbonate are passed into the urine, instead of being reabsorbed. Fanconi syndrome affects the proximal tubule, which is the first part of the tubule to process fluid after it is filtered through the glomerulus. It may be inherited, or caused by drugs or heavy metals.[2]
Different forms of Fanconi syndrome can affect different functions of the proximal tubule, and result in different complications. The loss of bicarbonate results in type 2 or proximal renal tubular acidosis. The loss of phosphate results in the bone disease rickets (even with adequate vitamin D and calcium), because phosphate is necessary for bone development.[3]
Eponym
It is named after Guido Fanconi, a Swiss pediatrician; this may be a misnomer, since Fanconi himself never identified it as a syndrome; though, as in the case of Goodpasture's syndrome, it is customary to name a syndrome after the first person to note a constellation of symptoms as occurring together.
It should not be confused with Fanconi anemia, a separate disease.
Clinical features
The clinical features of proximal renal tubular acidosis are:
- Polyuria, polydipsia and dehydration
- Hypophosphatemic rickets (in children) and osteomalacia (in adults)
- Growth failure
- Acidosis
- Hypokalemia
- Hyperchloremia
Other features of the generalized proximal tubular dysfunction of the Fanconi syndrome are:
- Hypophosphatemia/hyperphosphaturia
- Glycosuria
- Proteinuria/aminoaciduria
- Hyperuricosuria
Causes
In contrast to Hartnup disease and related tubular conditions, Fanconi syndrome affects the transport of many different substances, so is not considered to be a defect in a specific channel, but a more general defect in the function of the proximal tubules.[4]
Different diseases underlie Fanconi syndrome; they can be inherited, congenital, or acquired.
Inherited
Cystinosis is the most common cause of Fanconi syndrome in children.
Other recognised causes are Wilson's disease (a genetically inherited condition of copper metabolism), Lowe syndrome, tyrosinemia (type I),[5] galactosemia, glycogen storage diseases, and hereditary fructose intolerance.
Two forms, Dent's disease and Lowe syndrome, are X linked.[6]
Acquired
It is possible to acquire this disease later in life.
Causes include ingesting expired tetracyclines( where tetracycline changes to form epitetracycline and anhydrotetracycline which damage proximal tubule ), and as a side effect of tenofovir in cases of pre-existing renal impairment.[7][8] In the HIV population, Fanconi syndrome can develop secondary to the use of an antiretroviral regimen containing tenofovir and didanosine.[9] Lead poisoning also leads to Fanconi syndrome.[10]
Multiple myeloma or monoclonal gammopathy of undetermined significance can also cause the condition.[11]
Treatment
Treatment of children with Fanconi syndrome mainly consists of replacement of substances lost in the urine (mainly fluid and bicarbonate).
See also
- Familial renal disease in animals for Fanconi syndrome in Basenjis
References
- ^ "Fanconi syndrome" at Dorland's Medical Dictionary
- ^ Fanconi Syndrome at Merck Manual Home Health Handbook
- ^ Magen D, Berger L, Coady MJ, et al. (March 2010). "A loss-of-function mutation in NaPi-IIa and renal Fanconi's syndrome". N. Engl. J. Med. 362 (12): 1102–9. doi:10.1056/NEJMoa0905647. PMID 20335586.
- ^ Fanconi Syndrome at eMedicine
- ^ Cochat P; Pichault V; Bacchetta J; et al. (March 2010). "Nephrolithiasis related to inborn metabolic diseases". Pediatr. Nephrol. 25 (3): 415–424. doi:10.1007/s00467-008-1085-6. PMC 2810370. PMID 19156444.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Vilasi A; Cutillas PR; Maher AD; et al. (August 2007). "Combined proteomic and metabonomic studies in three genetic forms of the renal Fanconi syndrome". Am. J. Physiol. Renal Physiol. 293 (2): F456–F467. doi:10.1152/ajprenal.00095.2007. PMID 17494094.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Viread Label Information, U.S. Food and Drug Administration (FDA)), 2008-04-11
- ^ Tenofovir (Viread) Associated with Mild Kidney Function Impairment, but not Clinically Relevant Renal Disease, hivandhepatitis.com, 2008-10-14
- ^ Irizarry-Alvarado JM, Dwyer JP, Brumble LM, Alvarez S, Mendez JC (March 2009). "Proximal tubular dysfunction associated with tenofovir and didanosine causing Fanconi syndrome and diabetes insipidus: a report of 3 cases". AIDS Read. 19 (3): 114–21. PMID 19334328.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Barbier O, Jacquillet G, Tauc M, Cougnon M, Poujeol P (2005). "Effect of heavy metals on, and handling by, the kidney". Nephron Physiol. 99 (4): 105–p110. doi:10.1159/000083981. PMID 15722646.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Hashimoto T; Arakawa K; Ohta Y; et al. (2007). "Acquired fanconi syndrome with osteomalacia secondary to monoclonal gammopathy of undetermined significance" (– Scholar search). Intern. Med. 46 (5): 241–245. doi:10.2169/internalmedicine.46.1882. PMID 17329920.
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