CKD due to interstitial nephritis has been described with long-term use of bladder-wrack tablets.32 Kwan et al.33 described chronic interstitial nephritis in association with use of a Chinese herbal slimming pill containing anthraquinone derivatives extracted from Rhizoma Rhei (rhubarb). Vanherweghem et al.34 described progressive renal failure PF-02341066 molecular weight in a group of nine young women who were following a weight-loss
regimen in a specific slimming clinic. All of them had presented with advanced renal failure of unexplained aetiology, severe anaemia, minimal proteinuria, little or no oedema and small kidneys. Renal biopsies were done in eight of these and revealed extensive interstitial fibrosis with minimal glomerular changes. More cases with similar backgrounds soon came to light. Enquiries revealed that these women had been prescribed ‘slimming pills’ by the clinic. Composition of these pills had been modified in 1990 by addition of root extracts from two Chinese herbs, Stephania tetrandra and Magnolia officinalis. Chromatographic techniques
failed to show the expected peaks corresponding to tetrandine (a constituent of S. tetrandra) in check details the material obtained from the capsules, leading to a suspicion of substitution of this herb. In the traditional Chinese medical system, herbs are identified by their Pin Yin names. These names depend on the ‘therapeutic families’ to which these drugs belong; individual drugs within a family are identified by a prefix. S. tetrandra (Han Fang Ji), a member of the Fang Ji family, shares part of its name with Aristolochia fangchi (Guang Fang Ji).35 The known renal toxicity of aristolochic acid (AA), found in plants belonging to the Aristolochaceae family, led the investigators new to suspect the possibility of a substitution. This was confirmed when they found heavy AA content in several batches of herbs labelled as S. tetrandra.36 Clinching evidence came when AA-DNA adducts were identified in urothelial
tissue of patients using a 32P-post-labelling technique.37–41 Initially dubbed ‘Chinese herbal nephropathy’, this condition is now described more accurately as aristolochic acid nephropathy (AAN).42Aristolochia plants are used extensively in herbal preparations in China, Taiwan and Hong Kong, from where AAN is now being increasingly reported.43–47 Guh et al.48 determined the threshold dose at 30 g of Mu-Tong and 60 g of Fangchi. A similar disease pattern has been described in Europe (Germany, UK, France, Spain), Asia (Japan, Korea) and the USA. The presentation is insidious; renal failure is detected at either an advanced stage or incidentally on routine blood testing. Urinalysis shows minimal proteinuria and no sediment abnormality.34 Varying degrees of glycosuria, increased urinary excretion of low molecular weight proteins and occasional reports of full-blown Fanconi syndrome49 suggest that the tubulointerstitial compartment is affected.