Gut 1996; 38: 120-124

Use of whole gut perfusion to investigategastrointestinal blood loss in patients with irondeficiency anaemia

A Ferguson, W G Brydon, H Brian, A Williams, M J Mackie

AbstractIron deficiency anaemia may be due tooccult bleeding into the gut. However,although clinical investigations may showa high frequency of gastrointestinal tractdisease in these patients, the cause-effectrelationship between the lesions detectedand anaemia remain uncertain. Thisstudy aimed to establish whether lesionsdetected by endoscopy or imaging of thegastrointestinal tract in patients withunexplained iron deficiency anaemia arebleeding continuously. Routine clinicaltests were performed in 42 patients withunexplained iron deficiency anaemiareferred to this unit. Whole gut lavage andassay of haemoglobin in the gut perfusatewere also performed. The main outcomemeasures were clinical diagnoses (byimaging and endoscopy of the uppergastrointestinal tract and colon); the con-centration of haemoglobin in whole gutlavage fluid; and the calculated gastro-intestinal blood loss per day. There were73 clinical, dietary, or iatrogenic factors ofpossible aetiological importance in the 42patients - poor diet (10), gross gastro-intestinal abnormality (34 in 28 patients),malabsorption (14), coagulation problems(6), and NSAID use (9). The gut lavagetest showed, however, that at the time thetest was performed, only eight patientswere losing more than 2 ml blood dailyinto the gut, including all four with coloniccancer, one with diffuse gastric vascularectasia, and one with severe ulcerativeoesophagitis. It is concluded that occultgastrointestinal bleeding sufficient tocause anaemia was evident in only 19% of42 patients. There was a high frequency ofother potential causes ofiron deficiency inthe remainder, suggesting that most ofthe gastrointestinal diseases and lesionsdetected in them were probably coinci-dental. Factors other than blood lossshould be considered and treated inpatients referred for anaemia assessment.(Gut 1996; 38: 120-124)

Keywords: occult gastrointestinal bleeding, coloncancer detection, whole gut perfusion, dietary irondeficiency, iron malabsorption.

Iron deficiency anaemia may be the onlyclinical manifestation of ulcerative oesopha-gitis, benign or malignant gastric ulcer,duodenal ulcer, large benign colonic polyps, or

colonic cancer. Thus, it is normal clinicalpractice to examine the upper and lowergastrointestinal tract by x ray or endoscopy,or both, in patients with unexplained irondeficiency. High detection rates for lesionscapable of causing blood loss are reported - forexample, 57%, 60%, and 70% respectively inrecent series from the USA,1 Australia,2 andEngland.3 Accurate measurements of theamounts of blood lost into the gut in thesepatients have not been performed, however,and so the cause-effect relationships betweenthe lesions detected and the anaemia remainuncertain.We have recently reported that when peroral

gut lavage with a non-absorbable fluid is usedfor bowel cleansing, the clear fluid passed perrectum at the end of the procedure (whole gutlavage fluid, WGLF) is essentially a gutperfusate.4 For research purposes the lavage issupervised by an experienced nurse with adefined protocol for fluid ingestion, to give agut perfusion rate of around 20 ml per minute.Blood loss during the test, from any level of thegastrointestinal tract, can be detected andmeasured by assay of haemoglobin (Hb) inWGLF.5 We have used this new test in a seriesof patients with iron deficiency anaemia inorder to assess which of the gastrointestinallesions detected are chronically andcontinuously bleeding, and which are probablynot doing so.

Patients and methods

PATIENTSForty two patients referred to gastrointestinalphysicians with unexplained iron deficiencyanaemia were investigated over an 18 monthperiod. Twenty six were women aged between40 and 85 years (median 66) and 16 were menaged between 43 and 86 years (median 72).Entry criteria were a low blood Hb concentra-tion (<130 g/l in men, <115 g/l in women)together with two of the following: low meancell volume (<76 fl), low serum ferritin (<10,ug/l), low serum iron (<14 gumolIl), andreticulocyte response with rise in Hb after oraliron treatment.

In order to establish reference values for theWGLF Hb concentration, assays were per-formed in WGLF from 22 healthy volunteersand 15 patients with simple constipation ortrivial, functional gastrointestinal symptoms;there were 23 men and 14 women, median age32 years, range 19-86.

Reproducibility of the technique was

Gastro-Intestinal Unit,Departments ofMedicine andHaematology,University ofEdinburgh, WesternGeneral Hospital,EdinburghA FergusonW G BrydonH BrianA WilliamsM J Mackie

Correspondence to:Professor A Ferguson,Gastro-Intestinal Unit,Department of Medicine,Western General Hospital,Crewe Road, EdinburghEH4 2XU, UK.

Accepted for publication6 June 1995

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Whole gut perfsion to investigate GI blood loss

assessed indirectly, by examining results ofWGLF Hb measurements in pairs of sampleswhich had been collected from 40 patients orhealthy volunteers in the course of otherresearch projects, or as part of their routineclinical care, including 10 pairs of specimensfrom patients with active inflammatorybowel disease, before and after initiation oftreatment.

CLINICAL ASSESSMENTAs part of the initial clinical interview andexamination, we recorded not only gastro-intestinal symptoms and clinical signs but alsothe quality of the diet and current or recent useofNSAIDs, aspirin, or anticoagulants.Upper gastrointestinal endoscopy, rigid

sigmoidoscopy, and barium enema or colono-scopy, or both, were performed in 40 patients.In two patients, when the first endoscopyexamination showed a carcinoma (one gastric,one colonic) other booked investigations werecancelled. These patients have not beenexcluded from the series since examination ofthe gastrointestinal tract was completed atlaparotomy. Although the planned protocolincluded endoscopic duodenal biopsies for thediagnosis of coeliac disease, these were, in fact,obtained from only 25 patients, and a furtherthree had a Watson capsule biopsy of thejejunum.

GUT LAVAGE PROCEDUREGut lavage was performed as preparation forbarium enema or colonoscopy examination.Supervised by a research nurse, patients drankisotonic lavage fluid (Klean-Prep, NorgineLtd, UK), at a rate of one glass (200 ml) every10-15 minutes, until clear fluid was beingpassed per rectum. A sample was collected andstored at -70°C.

ASSAY OF HAEMOGLOBIN AND CALCULATION OFBLOOD LOSSHaemoglobin in WGLF was assayed by theHemoquant technique, which measures bacte-rially degraded as well as intact Hb.6 Theblood Hb concentration was measured in asample taken on the day of lavage and gastro-intestinal blood loss per day was calculated as:

WGLF Hb concentration (pg/iml)X28.8Bd c=met blood lostld

Blood Hb concentration (g/1)

(this assumes a perfusionmlImin=28.8 l/d).

rate of 20

Results

CLINICAL FEATURESInitial Hb values in the 16 men ranged from61-119 g/l (mean 90 g/l), and in the 26 womenthey ranged from 45-114 g/l (mean 85 g/l).Many patients had symptoms of anaemia suchas tiredness, lethargy, and breathlessness butfew had significant gastrointestinal symptoms.One woman developed dysphagia while

being investigated; five patients reporteddyspepsia, three heartburn, one constipation,and two diarrhoea.There were 10 patients whose diet was

clearly deficient in iron-containing foods (asjudged at clinical interview by one of us (AF,AW, or MM); formal dietary assessment wasnot performed. Nine patients had been takingNSAIDs when the anaemia was diagnosed butat the time of their gastrointestinal investiga-tions the drugs had been withdrawn from eightof the nine. Four patients had been on longterm anticoagulant therapy, which had beenstopped in one case. There was a furtherpatient with a bleeding diathesis due toidiopathic thrombocytopenic purpura and onewoman with alcoholic liver disease also hadabnormal coagulation.

MALABSORPTIONTwelve patients had a gastric abnormalitylikely to lead to iron malabsorption. Seven ofthe 12 had had a partial gastrectomy for pepticulcer disease many years previously and theother five had atrophic gastritis.

Small bowel biopsy tissue from one womanwith no gastrointestinal symptoms and a dietdeficient in iron showed pathology typical ofcoeliac disease. Coeliac disease was probablein one other patient with an oesophagealcarcinoma. She had old rickets and gave ahistory of macrocytic anaemia with a normalSchilling test 25 years ago; unfortunately theendoscopist had not taken a duodenal biopsybut ELISAs were positive for serum IgA andWGLF IgA antibodies to gliadin.7

OTHER GASTROINTESTINAL DISEASESDETECTEDStandard x ray and endoscopic investigationsproduced many positive results, including sixcarcinomas (Table I). Indeed there were onlyseven patients in whom no lesion was found:

TABLE I Gastrointestinal diseases and otherfactors ofpossible relevance to iron deficiency anaemia in 42 patients

No ofpatients

Malabsorption:Atrophic gastritisPartial gastrectomy without gastritisPartial gastrectomy with gastritisCoeliac-definiteCoeliac-probable

Other gastrointestinal diseases:Oesophagitis mildOesophagitis severe ulcerativeCarcinoma oesophagusHiatus herniaAcute gastritisGastric vascular ectasiaGastric carcinomaDuodenal ulcerCrohn's (ileum)Colon cancerBenign colonic polypsDiverticular disease

Abnormal coagulation:On anticoagulantsPreviously anticoagulated now stoppedIdiopathic thrombocytopenic purpuraAlcoholic liver disease

Drugs:Previously taking NSAIDCurrent on NSAID

Poor diet:Iron deficient diet

54311

411

102

i426

3

11

81

10

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Ferguson, Brydon, Brian, Williams, Mackie

*

Figure 1: Presence ofgastrointestinal (GI) diseases and of other aetiologicalfactors in 42patients with iron deficiency anaemia. In 28 patients, one or more gastrointestinal diseasewas detected by imaging or endoscopy, or both; in 10 the diet was judged by an experiencedclinician to be deficient in iron; and 14 patients had diseases associated with ironmalabsorption. As shown, there was significant overlap between these groups and with thepresence of other relevant factors such as use of non-steroidal anti-inflammatory drugs(NSAIDs) or coagulation abnormality.

two of these had iron deficient diets. one hadalcoholic liver disease, one had previouslytaken NSAIDs, leaving only three of the 42patients for whom we had completely negativefindings (Fig 1).

MEASUREMENT OF GASTROINTESTINALBLEEDINGValues for WGLF Hb in the 37 volunteers andpatients with a normal gastrointestinal tract,ranged from 1 0-5.4 ,g/ml (mean 2.50, SD1 13). We have therefore set the referencerange for this measurement as 1-5 pug/ml.

Thirty sets of duplicate samples were fromindividuals with normal values for WGLFHb at the first test. In all cases the value forthe second sample was also normal; mean

TABLE ii Concentrations ofIgG (reflecting diseaseactivity) and of haemoglobin, in whole gut lavage fluid(WGLF) from a series ofpatients with inflammatory boweldisease who had gut lavage performed twice within a fourweek period

IgG (pg/ml) in WGLF Hb (,ug/ml) in WGLF

On OnRelapse treatment Relapse treatment

Crohn's 55 24 10 5disease 93 60 22 9

144 82 162 145137 54 58 1427 9 12 9216 41 15 944 34 9 8101 11 14 4

Ulcerative 254 102 151 25colitis 188 2 23 4

difference in duplicate values was 0.96 ,ug/ml(range 0-3). There were 10 pairs of specimensfrom patients with inflammatory boweldisease, one sample collected in relapse, andone after a variable clinical improvement ontreatment. A shown in Table II, concentrationsof IgG and ofHb in WGLF parallelled diseaseactivity: Hb concentrations were lower in thespecimen collected after treatment, but in mostcases the values were still above the referencerange.Twenty five of the 42 patients with iron

deficiency had values for WGLF Hb within thenormal range. There were a further sevenpatients with marginally raised concentrations(6-8 ,ug/ml, calculated daily gastrointestinalblood losses 1.2-1.7 ml/d), including twopatients with malignant disease (gastric cancer,6 ,ug/ml, 1.2 ml/d, oesophageal cancer 6 ,ug/ml,1.3 ml/d). Two patients had WGLF Hb con-centrations of 10 and 12 ,ug/ml, withcalculated blood losses of borderline clinicalsignificance at 2.0 and 2-1 ml/d, and there wereonly eight patients with unequivocally highvalues (taken as WGLF Hb >10 pug/ml, andcalculated blood loss >2 ml/d during thelavage procedure) (Fig 2). This group includedall four patients with colon cancer (bloodlosses 5-132 ml/d).

DiscussionIn view of the very high rates of detection ofgastrointestinal diseases in anaemic patients, ithas been entirely reasonable to assume thatchronic blood loss from the gut is the com-monest cause of iron deficiency anaemia inmen and in postmenopausal women.8 Lack ofcorrelation with positive faecal occult bloodtest has generally been attributed to deficien-cies in the guaiac based faecal occult bloodmethods, which are relatively insensitive andpreferentially detect blood loss from thedistal gastrointestinal tract. A further factoris that bleeding may occur in the form ofmultiple intermittent episodes, rather than as acontinuous ooze.The accurate measurement of bleeding into

the gut requires a suitable assay for Hb or someother component of red blood cells, applied toa specimen representative of gut luminalcontents - ideally a complete five or seven dayfaecal collection or several separate faecalsamples. Problems associated with tests onfaeces include not only the resistance to collec-tion and handling of faecal specimens bypatients, nurses, and laboratory staff, but alsothe potential interference in analyses byresidues of meat and other dietary con-stituents. Patient-related variables such asintestinal transit time and faecal bulk are alsorelevant. The Hemoquant method is a highlysensitive analytical technique, which measuresboth intact and bacterially metabolisedhaemoglobin7; when this is used to test a timedspecimen of faeces collected after a period on ameat free diet, it can detect and quantify bloodloss from the proximal or distal gut. We havepreviously reported that this method can alsoreadily be used with WGLF.5 Use of gut

= Gross GI pathologyPoor diet

M MalabsorptionOthers

* NSAIDS0 Coagulation abnormal

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Whole gut perfusion to investigate GI blood loss

is^

. 50XfiA

\~~~~~ Grc_|||

\~~~~~ Pocl_l * E

Ma

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sS GI pathologyor dietilabsorption |hers

Figure 2: Distribution (within the classification shown in Figure 1) and diagnosis, for the eight patients in whomgastrointestinal blood loss (based on the whole gut lavage fluid test) was estimated to be more than 2 ml daily.

perfusion fluid as an assay material overcomesthe need for dietary restrictions and unpleasantfaecal collections, and specimens can beobtained when peroral gut lavage is being usedto cleanse the bowel before colonic investiga-tions. The reference range for WGLF Hbconcentrations, 1-5 ,ug/ml, equates to dailyblood losses of around 0.2-1 ml/d. The maintheoretical disadvantage of this new test ofgastrointestinal bleeding is that the samplingtime is limited to a few hours; further experi-ence, and comparisons between WGLF andfive day faecal collections, should show howfrequently occult bleeding is discontinuous,and in what time frame.

Review of the results of WGLF Hbmeasurements highlights the complexity ofpossible aetiologies in the 42 iron deficientpatients studied. Altogether 73 clinical,dietary, or iatrogenic factors were recorded -

poor diet (10), gross gastrointestinal abnor-mality (34 in 28 patients), malabsorption (14),coagulation problems (6), and NSAID use (9).However, out test of gastrointestinal bleedingdetected only eight patients who were losingmore than 2 ml blood daily into the gut,including all six patients with lesions generallyrecognised to be important causes of occultbleeding - four with colonic cancer, one withdiffuse gastric vascular ectasia, and one withsevere, ulcerative oesophagitis.There are several possible explanations for

the findings. In some patients with low ornormal values for WGLF Hb, gastrointestinalbleeding may be intermittent rather than a

continuous ooze, as discussed above. Thelesion responsible for blood loss might havehealed in the interval between diagnosis ofanaemia and investigation. This may well havebeen the case in NSAID treated patients, eightof whom had the drugs stopped as soon as

anaemia was recognised. It seems likely,

however, that in many instances, thegastrointestinal lesions detected by standardinvestigations were simply not bleeding, andthe anaemia was the result of some othercause. In the patients with calculated dailyblood loss of less than 2 mld, based on theWGLF test, there was a high frequency ofother conditions which might lead to irondeficiency, such as poor diet or malabsorption.Regrettably, in developing the protocol for thestudy we did not arrange a formal assessmentof dietary iron intake, but a general appraisal ofthe diet was made by an experienced andnutritionally aware clinician. Nevertheless, thisis an example of how the emphasis which we

and others have placed on the development ofbetter tests for gastrointestinal bleeding leadsto relative neglect of these other clinicallyimportant features.

Absorption and bioavailability of dietaryiron, and iron malabsorption, are partly inter-related. The amount of inorganic iron which isabsorbed is greatly influenced by the nature ofother foods taken at the same time.10 A muchhigher proportion of haem iron than inorganiciron is absorbed,1' 12 and malabsorption syn-dromes may affect one and not the other - forexample, in coeliac disease there is malabsorp-tion of ferrous but not of haem iron.'13 Optimalinorganic iron absorption requires healthygastric and small bowel mucosae, and so willbe compromised after gastric surgery, andprobably also in patients with atrophic gastritisand hypochlorhydria. There were seven (17%)patients in our series who had had a

partial gastrectomy many years before. Coeliacdisease may be expressed as a single nutrientdeficiency, and some form of small bowelbiopsy should be included in the investigationof all iron deficient patients. Free iron lossinto the gut in association with high rates ofepithelial cell proliferation and loss, is another

Diagnosis Blood loss/d(ml)

Carcinoma 132Colon 20

65

Severe diverticulardisease and mnidoesophagitis 10

Gastric vascularectasia 8

Ulcerativeoesophagitis

PreviousNSAID use

4

BK

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124 Ferguson, Brydon, Brian, Williams, Mackie

potential factor in patients with coeliac diseaseor gastritis.14

In iron deficient patients reported recently,serious diseases detected vary somewhatbecause of different aims of the studies, entrycriteria, age, and sex. However, in all reports,a significant minority of patients withunexplained anaemia is found to havecompletely asymptomatic colonic cancer -9.5% of our 42 patients - a good yield ofpotential curable, serious disease. There is noreason to change current clinical practice;patients with unexplained iron deficiencyshould have colorectal endoscopy or imaging,and probably upper gastrointestinal endoscopyat the same time. But in the majority who donot have colorectal cancers, more attentionneeds to be paid to the completion of thediagnostic process - separate recognition ofbleeding and non-bleeding lesions, or dietaryiron deficiency, and of iron malabsorption dueto hypochlorhydria or coeliac disease.This work was supported by grants from the Scottish HospitalsEndowments Research Trust, and Fisons pharmaceuticals.

1 Rockey DC, Cello JP. Evaluation of the gastrointestinaltract in patients with iron-deficiency anemia. N Engl JfMed 1993; 329: 1691-5.

2 Cook IJ, Pavli P, Riley JW, Goulston KJ, Dent 0.Gastrointestinal investigation of iron deficiency anaemia.BMJ 1986; 292: 1380-2.

3 McIntyre AS, Long RG. Prospective survey of investiga-tions in outpatients referred with iron deficiency anaemia.Gut 1993; 34: 1102-7.

4 O'Mahony S, Barton JR, Crichton S, Ferguson A. Appraisalof gut lavage in the study of intestinal humoral immunity.Gut 1990; 31: 1341-4.

5 Brydon WG, Ferguson A. Haemoglobin in gut lavage fluidas a measure of gastrointestinal blood loss. Lancet 1992;340: 1381-2.

6 O'Mahony S, Arranz E, Barton JR, Ferguson A.Dissociation between systemic and mucosal humoralimmune responses in coeliac disease. Gut 1991; 32:29-35.

7 Schwartz S, Dahl J, Ellefson M, Ahlquist DA. TheHemoquant test; a specific and quantitative assay of heme(hemoglobin) in feces and other materials. Clin Chem1983; 29: 2061-7.

8 Beveridge BR, Bannerman RM, Evanson JM, Witts U.Hypochromic anaemia. QJ'Med 1965; 34: 145-61.

9 Sayer JM, Long RG. A perspective on iron deficiencyanaemia. Gut 1993; 34: 1297-9.

10 Charlton RW, Bothwell TH. Iron absorption. Ann Rev Med1983; 34: 55-68.

11 Bjorn-Rasmussen E, Hallberg L, Isaksson B, Arvidsson B.Food iron absorption in man. Applications of the 2 poolextrinsic tag method to measure haem and non haem ironabsorption from the whole gut. Y Clin Invest 1974; 53:247-55.

12 Young GP, Rose IS, Stjohn DJB. Haem in the gut I. Fate ofhaemoproteins and the absorption ofhaem. J GastroenterolHepatol 1989; 4: 537-45.

13 Anand BS, Callender ST, Warner GT. Absorption ofinorganic and haemoglobin iron in coeliac disease.Br7Haematol 1977; 37: 409-14.

14 Sutton DR, Stewart JS, McL Baird I, Coghill NF. Free ironloss in atrophic gastritis, post gastrectomy states, andadult coeliac disease. Lancet 1970; i: 387-90.

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