Laxative induced diarrhoea- a neglected diagnosis - Europe PMC

Journal of the Royal Society of Medicine Volume 85 April 1992

203

Laxative induced diarrhoea - a neglected diagnosis

A Duncan PhD1 A J Morris MBChB MRCP1 A Cameron AIMLS1 M J Stewart PhD FRCPath2 W G Brydon MRCPath3 R I Russell PhD FRCP1 'Gastroenterology Unit and 2Institute of Biochemistry, Royal Infirmary, Glasgow G31 2ER and 3Gastrointestinal Laboratory, Western General Hospital, Edinburgh EH4 2XU Keywords: chronic diarrhoea; laxative abuse; medical audit

Summary A laxative screening service was established and offered to gastroenterologists in hospitals covering the West and Central belt of Scotland. The prevalence of laxative induced diarrhoea was assessed in two populations and was found to be 4% in new patients presenting to a gastroenterology clinic with diarrhoea and 20% in patients already under investigation of chronic idiopathic diarrhoea. A high rate of missed diagnosis of laxative induced diarrhoea (71%) and a low request rate (eight per annum) confirm the low clinical awareness of this diagnosis. We found potential savings of 80% of the cost of investigations subsequently ordered which could have been avoided by performing laxative screens on all patients presenting with diarrhoea. The introduction of such a screening policy is recommended as a cost-effective measure.

Introduction The medical importance of identifying patients who induce diarrhoea by self-administration of laxatives has previously been highlightedl-3. Failure to make an early diagnosis may result in these patients undergoing extensive investigations including laparotomy4. Patients usually ingest laxatives surreptitiously and so the diagnosis can only be made by the eventual admission of laxative ingestion by the patient, by finding laxatives in the patient's belongings, or by chemical identification of the drug in urine or stool. The latter approach is the most appropriate since most laxative abusers do not admit ingesting purgatives and searching of patient's belongings has ethical implications5 and requires an inpatient stay. Thin layer chromatography (TLC) methods have now been established for the detection of stimulant laxatives6-8 allowing the diagnosis to be more readily made. In 1974 Cummings et al suggested that an important factor in the diagnosis of laxative induced diarrhoea is a high degree of clinical suspicion'. Fifteen years on, Bytzer et al demonstrated a continued lack of awareness of the diagnosis despite the introduction of better chemical methods and concluded that a laxative screening programme is justified9. Our local experience is that laxative abuse is not considered until late in the course of investigation of diarrhoea and until recently no method for detecting laxatives was available in our area. In 1987 we established a TLC method for detecting laxatives and offered it as a routine service to gastroenterologists and biochemists in Glasgow and the West and Central belt of Scotland. We have investigated the potential savings in investigation

and inpatient costs in those patients in whom laxative induced diarrhoea was subsequently diagnosed. This paper documents our 2-year experience of the TLC method, the prevalence of laxative induced diarrhoea (LID), and the financial implications of missing this diagnosis.

Materials and methods Laxative screening service The laxative screening service was offered in writing to all gastroenterologists and biochemists in the principal hospitals in six of the health boards in Scotland (Greater Glasgow, Argyll and Clyde, Forth Valley, Lanarkshire, Ayrshire and Arran, and Dumfries and Galloway), covering approximately 52% (2 751 600 at June 1987) of the country's population'0. Patients were asked to provide a urine sample during their clinic appointment or to return a random urine specimen (collected at a time when they had diarrhoea). Patients Group 1: Patients on whom a routine request was made for the laxative screening service over the 2-year period since its introduction.

Group 2: In order to assess the prevalence of laxative induced diarrhoea the casenotes of outpatients due to attend the gastroenterology clinic were screened and the following two populations identified: (a) 49 patients referred to our gastroenterology clinic from general practitioners for the investigation of diarrhoea; (b) 10 patients who had already been extensively investigated for chronic diarrhoea of unknown origin. Table 1. Laxatives available over the counter

Laxative

Proprietary drug

Phenolphthalein Boldomint, Carter's Little Pills, Ex-Lax, Fam-Lax, Feen-a-Mint, Juno Jupiter Tablets, Kest, Nylax, Reguletts, SureLax, Alophen Pills Bisacodyl Nylax Sennoside California Syrup of Figs, Eucarbon, Nylax, Sennokot, Boots Senna Tablets Beecham's Pills, Carter's Little Pills, Aloin Nylax Cascara California Syrup of Figs, Nylax, Alophen

Frangula

Pills Normacol

0141-0768/92/

040203-03/$02.00/0 © 1992 The Royal Society of Medicine

204


Table 2. Summary of findings in patients with laxative induced diarrhoea

Patient

Time to diagnosis

Denial of laxative

Diagnosis suspected

Diagnosis

1 2 3 4 5 6 7

1 6 9 8 9 18 6

Yes Yes No Yes Yes Yes Yes

No No Yes No No No No

?LID/?irritable bowel syndrome Irritable bowel syndrome ?Irritable bowel syndrome/?LID ?Irritable bowel syndrome/?Crohn's disease/?tuberculosis ?Irritable bowel syndrome/?amyloid Irritable bowel syndrome Irritable bowel syndrome

month months months years months months months

Laxative measurement Laxatives were detected in urine by an adapted TLC method4 using 4-methyl-2-pentanone: chloroform: acetic acid (5: 2: 1) as the solvent system. To confirm the presence of laxatives, the mobilities of all positive samples were checked using a different solvent system (hexane: toluene: glacial acetic acid, 3: 1: 1). Table 1 shows over-the-counter laxatives detectable by this method.

Costing procedure In nine patients in whom the diagnosis of laxative induced diarrhoea was delayed we calculated the costs of investigations and inpatient care that were retrospectively judged to be unnecessary. For the costing analysis four of these patients were recruited from an Edinburgh hospital which employs a similar TLC method. The case records were reviewed by a gastroenterologist who retrospectively judged which investigations could have been avoided had an early screen been performed. In these patients routine haematology, biochemistry, and sigmoidoscopy with biopsy were allowed. In those over 45 years of age barium enema examination was also considered to be appropriate. Laboratory tests were costed predominantly using the Welcan system" and inpatient stays were costed at £200 daily. The cost of a laxative test in our laboratory is £40 when performed individually but is reduced to £24 when there are sufficient samples for batch-analysis. Results Group 1 Over the 2-year period, 16 requests for laxative screen were made, three of which originated from hospitals other than those originally notified. Ofthe 16 requests made, 10 (63%) were for investigation of unexplained diarrhoea, three (19%) in patients with eating disorders, and the remaining three for investigation of infantile diarrhoea, red urine, or long-standing unexplained hypokalaemia. The test was positive in three patients (19%): one with unexplained diarrhoea (patient 1, Table 2), a patient with anorexia nervosa who presented with red urine, and the patient with

unexplained hypokalaemia.

Group 2a In 4% (2 of 49) of new patients presenting with diarrhoea the complaint was found to be self-induced (patients 2 and 3, Table 2). Group 2b In patients who were being investigated for chronic diarrhoea of unknown origin, 20% (2 of 10) gave positive urinary results for laxatives (patients 4 and 5,

Table 2). A further two patients (patients 6 and 7, Table 2) with chronic idiopathic diarrhoea who were being routinely investigated were fortuitously found to be taking laxatives (see Discussion). The clinical findings in these patients with laxative induced diarrhoea are summarized in Table 2. Of the seven patients the diagnosis was unsuspected in five (71%). In eight patients on whom the diagnosis was initially unsuspected, an average of £2807 (range of £60-£10 709) was spent on investigations which would have been unnecessary had an early laxative screen been performed. Discussion Surreptitious ingestion of laxatives is a well-recognized cause of chronic idiopathic diarrhoea. Nevertheless, two aspects of this study suggest that there is still a low clinical awareness ofthe condition. Firstly, the very low request rate of eight requests per year from a population area of 2.7 million, and secondly, a high rate of missed diagnosis (71%). The latter figure concurs with a previous study in which the diagnosis was unsuspected in 57%9. This failure to consider a diagnosis of laxative abuse was exemplified in two of our patients with chronic diarrhoea in whom the diagnosis was fortuitously made in the laboratory; alkalinization of stool samples (one during a faecal fat procedure and one while cleaning contaminated glassware with an alkaline detergent) revealed the characteristic purple colour of phenolphthalein. Its presence was subsequently confirmed by TLC. We found that the diagnosis of laxative induced diarrhoea (LID) was often mistaken for irritable bowel syndrome (IBS): of seven patients a diagnosis of IBS had been made in three, and was, or had been, considered in the other four. One possible reason for the low clinical suspicion is that LID is considered only in patients with copious diarrhoea. Previous studies suggest that the diarrhoea induced by laxatives is severe"1'2"13 and individual reports often quote patients with gross diarrhoea. For example, Read et al. found the average daily stool weight to be 1.1 litres (range=325-2561 g/day)14. However, in most of our patients with LID the diarrhoea was of relatively low volume with an average daily stool weight of 443 g (range of 253-950 g). It is possible that a considerable number of patients with LID remain undiagnosed. We found the prevalence in new patients presenting with diarrhoea to be 4%. This figure is considerably lower than the 15% found in a Danish study9. The reason for the disparity may be related to cultural reasons or availability of laxatives. Anthraquinone laxatives were most commonly abused in the Danish study while


in ours and an American study15 phenolphthalein abuse was predominant. In our small group with chronic idiopathic diarrhoea 20% were found to be laxative-induced. This figure, which is broadly comparable with the 13% and 15% detection rates found in previous studies14'16, again indicates a low clinical awareness of laxative abuse. Failure to make a diagnosis of LID can have considerable financial implications because of the inpatient stays and clinical investigations which are performed in the continued search for a diagnosis. In the present study the expenditure which in retrospect was unnecessary amounted to an average of £2807 per patient. In comparison, the cost of performing a laxative screen on all patients presenting with diarrhoea can be estimated at £600 for each laxative abuser diagnosed (assuming the prevalence is 4% and a laxative screen costs £24). This represents a potential four to five fold saving in investigation and inpatient costs and an unquantified expenditure on drugs and outpatient consultations. It is difficult to identify patients with LID clinically. We found these patients to have an increased likelihood of weight loss, hypokalaemia or symptoms suggestive of a psychological complaint. However, these features are not specific for laxative abuse and their presence cannot be used to select those on whom a laxative screen should be performed. In view of the relative frequency of LID, the continued low index of clinical suspicion, and the financial implications of failing to make this diagnosis, we suggest that a laxative screen be performed on all new patients referred for investigation of diarrhoea. References 1 Cummings HJ, Sladen GE, James OF, Sarner M, Misiewicz JJ. Laxative-induced diarrhoea: a continuing clinical problem. BMJ 1974;i:537-43 2 Krejs GJ, Walsh JH, Morawski SG, Fordtran JS. Intractable diarrhoea. Intestinal perfusion studies and plasma VIP concentrations in patients with pancreatic

3 4 5

6 7 8 9

10 11

12 13 14

15

16

cholera syndrome and surreptitious ingestion of laxatives and diuretics. Am J Dig Dis 1977;22:280-93 Slugg PH, Carey WD. Clinical features and follow-up of surreptitious laxative users. Cleve Clin Q 1984; 51:167-71 Cummings JH. Progress report. Laxative abuse. Gut 1974;15:758-66 Case 35. Case records of the Massachusetts General Hospital: weekly clinicopathological exercises. N Engl J Med 1979;301:488-96 Morton J. The detection of laxative abuse. Ann Clin Biochem 1987;24:107-8 de Wolff FA, de Haas EJM, Verweij M. A screening method for establishing laxative abuse. Clin Chem 1981;27:914-17 Duncan A, Cameron A, Stewart MJ, Russell RI. Diagnosis of the abuse of magnesium and stimulant laxatives. Ann Clin Biochem 1991;28:568-73 Bytzer P, Stockholm M, Andersen I, Klitgaard NA, Schaffalitzky de Muckadell OB. Prevalence of surreptitious laxative abuse in patients with diarrhoea of uncertain origin: a cost benefit analysis of a screening procedure. Gut 1989;30:1379-84 Scottish Development Department. Population and vital statistics, 1987 Bennett CHN. WELCAN UK: its development and future. J Clin Pathol 1991;44:617-20 Ewe K, Karbach U. Factitious diarrhoea. Clin Gastroenterol 1986;15:723-40 Moriarty KJ, Silk DBA. Laxative abuse. Dig Dis 1988;6:15-29 Read NW, Krejs GJ, Read MG, Santa Ana CA, Morawski SG, Fordtran JS. Chronic diarrhoea of unknown origin. Gastroenterology 1980;78:264-71 Krejs GJ, Fordtran JS. Diarrhea. In: MH Sleisenger, JS Fordtran, eds. Gastrointestinal disease: pathophysiology, diagnosis and management, 3rd edn. Philadelphia: WB Saunders, 1983:257-80 Ladefoged K, de Muckadell Schaffalitzky OB, Jarnum S. Faecal osmolality and electrolyte concentrations in chronic diarrhoea: Do they provide diagnostic clues? Scand J Gastroenterol 1987;22:813-20

(Accepted 16 July 1991)

205