clostridium difficile - associated diarrhoea ( cdad ) represents the leading cause of nosocomial diarrhoea in europe and north america [ 1 , 2 ] . it occurs most frequently in the elderly , immunocompromised or long - term care residents , and in association with broad - spectrum antibiotic use . however , there are increasingly numerous reports of community - acquired cdad [ 2 , 3 ] , occurring in individuals who have had no contact with a healthcare facility in the preceding 12 weeks . a recent united kingdom - based study demonstrated a 2.1% prevalence of toxin positivity in community - acquired diarrhoeal samples . the toxins of c. difficile have also been found in 3 - 5% of faecal specimens from asymptomatic members of the population , making it difficult to ascertain the true prevalence of community - acquired cdad [ 2 , 4 , 5 ] . acute renal failure ( arf ) is common in the hospital setting , particularly in the elderly and in response to hypovolaemia , but is only rarely described as a direct result of cdad . mckittrick - wheelock syndrome was originally described in 1954   and has been reported in the literature on fewer than 50 occasions since . the syndrome encompasses a triad of ( i ) profound volume and electrolyte depletion secondary to ( ii ) hypersecretory mucous diarrhoea arising from ( iii ) a giant villous adenoma of the rectum or sigmoid colon . in this report we describe the clinical presentations and outcome of a patient who suffered two separate episodes of arf , with complete functional recovery in the interim , arising from these two rare and independent colonic pathologies . a brief review of cdad and mckittrick - wheelock syndrome is also presented . in july 2007 , a 65-year - old obese caucasian british woman , with a family history of colorectal carcinoma ( mother and grandmother ) , was admitted acutely to hospital . she reported 2 weeks of general malaise and had stopped all oral intake over the prior 48 h. she described 24 h of vomiting , syncopal episodes and double incontinence of profuse brown liquid faeces and offensive urine . her blood results indicated sepsis , hypokalaemic metabolic acidosis , salt and water depletion and arf ( table 1 ) . she was resuscitated with intravenous fluids , administered intravenous gentamicin and meropenem and immediately taken to the intensive therapy unit where she remained on inotropic support ( dobutamine ) and haemofiltration for 3 days . a blood film demonstrated leukopaenia , large platelets without fragmentation and toxic granulation of neutrophils , consistent with an infective aetiology . after 48 h on the intensive therapy unit , a sample of the patient 's diarrhoea taken on initial arrival at hospital confirmed the presence of c. difficile toxin ( premier toxins a and b elisa , meridian bioscience inc . ) . after confirming with the patient 's general practitioner that there had been no recent exposure to antibiotics , she was diagnosed with community - acquired c. difficile infection . treatment was changed to intravenous metronidazole and oral vancomycin and the other antibiotics were discontinued . she returned home 2 days later with a normal creatinine of 89 mol / l and a urea of 5.8 mmol / l . in november 2008 , the patient returned with a shorter 48-hour history of vomiting , anuria and falls . initial assessment found her in better condition than when she had originally presented in july 2007 . she was in arf , however without evidence of circulatory shock , sepsis or acidaemia ( table 1 ) . on this occasion she revealed that she had been producing frequent , clear mucus stools for an indeterminate number of weeks . again , there was no preceding history of antibiotic use , but stool samples were negative for c. difficile toxin . digital rectal examination by a junior doctor revealed an unusual spongy feel to the wall of the rectum . this was therefore followed by flexible sigmoidoscopy and magnetic resonance imaging to discover an extensive , circumferential soft fleshy lesion , carpeting 90% of the rectum from 2 cm above the anal verge to a depth of 12 cm ( fig . initial management with intravenous fluid and electrolyte replacement returned her renal function to baseline levels within 48 h. definitive treatment , however , required surgical resection of the lesion . following pre - operative counseling the patient elected non - restorative surgery and underwent laparoscopically - assisted abdomino - perineal excision of the rectum , as the extent of the tumour made it unamenable to local resection . the patient unfortunately suffered postoperative adhesional bowel obstruction ( a small bowel loop adherent within the pelvis ) necessitating re - intervention 4 weeks later in the form of an ileocaecal resection and double - barrelled ileostomy - colonic mucus fistula formation . approximately 8 litres of secretions and additional fluids pass through the gastrointestinal tract per day , with less than 100 ml eventually entering the faeces . alterations to colonic epithelial permeability , transit time , or intestinal content may destabilise this balance towards net loss . severe or prolonged diarrhoeal illnesses can cause excessive depletion of salt and water from the gastrointestinal tract , leading to hypovolaemia , renal hypoperfusion and acute renal injury . the biochemical picture is usually one of hyperchloraemic metabolic acidosis with a normal anion gap , as there is a primary loss of bicarbonate from the gastrointestinal tract , with a compensatory hyperchloraemia . in contrast , villous adenomas produce a secretory mucous diarrhoea that contains large amounts of potassium , sodium and chloride so that the classical clinical picture is one of hypokalaemic , hypochloraemic metabolic acidosis with a high anion gap [ 8 , 9 ] . our patient presented on both occasions with arf , hyponatraemia and profound hypovolaemia requiring urgent fluid and electrolyte resuscitation , which is fundamental to successful treatment . unfortunately the serum chloride and anion gap were not measured during either admission , which might have been helpful in formulating a differential diagnosis . although her rectal adenoma may well have been present and contributing to the intestinal discharge at her first presentation , given the clinical , serological and microbiological findings at the time , on balance of probabilities this was most likely a near - fatal manifestation of severe community - acquired cdad . community - acquired cdad is more likely to occur in elderly patients with certain co - morbidities and risk factors ( table 2 ) . clinical infection with c. difficile is almost always associated with initial disruption of the colonic microflora by broad - spectrum antibiotics [ 3 , 4 , 11 ] . then follows the expression of at least two major toxins the latter irreversibly glycosylates members of the ras family of small gtpases , causing degradation of the actin cytoskeleton and disruption of epithelial tight junctions . the colonic epithelium becomes inflamed and begins to lose salt and water , resulting in a profuse diarrhoea . it follows that a prolonged episode of diarrhoea would eventually result in systemic losses of salt and water , and thus hypovolaemic renal failure . interestingly however , there are only 4 reports of this in the literature . despite its b toxin modifying small gtpases involved in transcriptional regulation , cellular proliferation and apoptosis , there are no reports of c. difficile infection promoting adenomatous transformation of the colonic epithelium such as would link our patient 's two pathologies . her second presentation was consistent with the syndrome originally described by mckittrick and wheelock   as evidenced by the extensive hypersecretory rectal adenoma . to effect significant volume loss , the adenoma underlying mckittrick - wheelock syndrome must measure some 7 - 18 cm in greatest dimension and cover a large percentage of the mucosal surface of the rectum or sigmoid colon , as more proximal adenomas may still allow for sufficient reabsorption of effluent [ 12 , 13 ] . the rarity of the syndrome is therefore explained by autopsy studies which have demonstrated that only 13 - 16% of villous adenomas reach > 2 cm in diameter , of which only 3% are secretory . with regards to clinical management , the high rate of malignant transformation in large villous adenomas [ 9 , 13 ] , and mortality attached to untreated mckittrick - wheelock syndrome [ 9 , 13 ] , suggests that pharmacological control of volume loss by the potent cox inhibitor indomethacin should only be considered as a temporising measure until the patient is stabilised for definitive surgical resection [ 9 , 12 , 14 ] . our patient has done well following rectal excision , without any lasting evidence of renal impairment or further episodes of arf . in summary , we have described two episodes of arf resulting from two uncommon and independent colorectal pathologies in order to highlight their importance when considering the differentials of arf in diarrhoeal disease .
we report the case of a 65-year - old caucasian woman who experienced two separate episodes of acute renal failure within an 18-month period , both requiring emergency admission and complicated treatment . 
 each episode was precipitated by hypovolaemia from intestinal fluid losses , but from two rare and independent pathologies . 
 her first admission was attributed to community - acquired clostridium difficile - associated diarrhoea ( cdad ) and was treated in the intensive therapy unit . 
 she returned 18 months later with volume depletion and electrolyte disturbances , but on this occasion a giant hypersecretory villous adenoma of the rectum ( mckittrick - wheelock syndrome ) was diagnosed following initial abnormal findings on digital rectal examination by a junior physician . 
 unlike hospital - acquired c. difficile , community - acquired infection is not common , although increasing numbers are being reported . whilst community - acquired cdad can be severe , it rarely causes acute renal failure . 
 this case report highlights the pathological mechanisms whereby c. difficile toxin and hypersecretory villous adenoma of the rectum can predispose to acute renal failure , as well as the values of thorough clinical examination in the emergency room , and early communication with intensivist colleagues in dire situations .