Aristolochic Acid Nephropathy

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Aristolochic acids (AA) are found in
products derived from the aristolochia genus of plants which are used
extensively in herbal medicines, particularly in Asia. Nephrotoxicity resulting
from AA exposure was originally described in a case series of women taking diet
supplements in Belgium but has subsequently been identified in the US, Europe
and Asia. Consumption of products containing AA remains endemic in some areas
with an estimated exposure in up to 40% of the Taiwanese population. The
disease known as Balkan endemic nephropathy – described the population living
around tributaries of the Danube river- is now thought to result from contamination
of wheat flour with seeds of plants containing AA.
Patients with AA nephropathy typically
present with renal insufficiency and anemia. Urinalysis reveals a few red cells
and mild proteinuria. The rate of decline of renal function varies but may depend
on the cumulative dose of AA. Renal histology is characterized by extensive
interstitial fibrosis with tubular atrophy and low numbers of inflammatory
cells. There is a very high incidence of urothelial atypia and carcinoma.
Exposure to AA can be confirmed by the presence of AA-DNA in biopsy
tissue. 

Therapy consists of routine management of
CKD alongside regular screening for urothelial malignancy. A trial of steroids
can be considered in selected patients. The risk of urothelial malignancy is so
high that some consider patients for bilateral nephrouretecomy once RRT as been
established.
Despite being banned in many countries,
products containing AA remain available. The true incidence of CKD and
urothelial malignancy resulting from AA exposure remains unknown. It is
possible that a lack of awareness means that a significant proportion of AA
resulted morbidity remains undiagnosed. 
For a comprehensive review of the subject see here.
Image from Wikipedia.
Posted by Jonathan Dick

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