rice bread, a gluten-free flour mix, buckwheat, and one preparation of wheat starch. 9 uniformly gave results for gluten above the cut-off; these were spaghetti bolognese, egg-and-bacon breakfast, crispbread, a malted drink, porridge, barley, plain flour, and two other samples of wheat starch. For 11 foods results from different laboratories were discordant; these were egg-and-bacon breakfast, beer, low-alcohol lager, stout, a purportedly gluten-free loaf, potato crisps, one sample of purportedly gluten-free flour, millet, gravy powder, cornflour, and rice pudding. For the higher gluten contents laboratories showed disagreement over the amount, this variation often being by a factor of 5 or 6 and in one case a 100. These results should be considered in conjunction with those reported by Dr Skerritt and Ms Hill (Feb 16, p 379) in assisting patients with coeliac disease (and their medical advisers) to decide whether to use in the home kits to detect gluten in food. these
C. C. BOOTH
St James’s University Leeds LS9 7TF, UK Academic
M. S. LOSOWSKY of Paediatric
Department Gastroenterology, St Bartholomew’s Hospital, London EC1
J. A. WALKER-SMITH
J. D. W. WHITNEY, Medical trustees, Coeliac Trust, PO Box 220, High Wycombe, Bucks
Magnesium and chronic fatigue syndrome SIR,-Mr Cox and his colleagues (March 30, p 757) correctly that antidepressants may help the treatment of depression and anxiety in chronic fatigue syndrome (CFS). They could have added
Ulceration after small-bowel enteroscopy.
Upper view shows ulceration and notching of a small-bowel fold during enteroscopy, lower view shows the same fold 24 h later
publish photographs of the lesions described. The enteroscope can injure small-bowel mucosa causing what appear to be ulcerative lesions (figure). The differentiating feature between a true small intestinal ulcer and an enteroscope-induced ulcer is that of notching of valvulae conniventes. This notching is secondary to the shaft of the enteroscope and accounts for ulcerations that measure 5 mm in diameter. Initially these may appear as red lesions on folds, but with protracted rubbing of the enteroscope ulcerations and notching occur. The frequency of this trauma is not known. Our experience with small-bowel enteroscopy in over 500 patients with obscure gastrointestinal bleeding at thee Mount Sinai Medical Center in New York has revealed an overall yield far less than 66%, and I am concerned that Morris et al ascribe all of their lesions to true non-steroidal medication effect. Division of Gastroenterology, Mount Sinai Medical Center, New York 10029, USA
that evidence from studies of fibromyalgia, a condition almost indistinguishable from CFS,l has shown these drugs to be effective in fatigue and in myalgia.z,3 Nevertheless, Cox et al state that such treatments "may be counterproductive", because they are associated with psychogenic illnesses. It is difficult to conceive of drugs whose action involves alterations in the level of several cerebral neurotransmitter systems as "psychogenic". By the same token, magnesium, which according to the Nottingham health profile scores has altered energy, emotional reactions, sleep, and social isolation, must also be seen as psychogenic, and thus counterproductive. What this demonstrates is how the choice of treatment in CFS continues to be determined not by what might be effective, but by outdated and unhelpful distinctions between "organic" and "psychogenic" or "real" and "unreal".’ It is sad to fmd such dualistic concepts appearing in a paper associated with the Centre for the Study of Complementary Medicine. Department of Psychological Medicine, King’s College Hospital, London SE5 9RS, UK 1.
BLAIR S. LEWIS
Inter-laboratory variation in gluten detection by ELISA kit SIR,-In early 1990 Qlone Laboratories made available to the Coeliac Society of Great Britain a small supply of gluten-testing kits of the type intended to be used by laboratory staff. After assessment in a laboratory with a long-standing interest in coeliac disease (St James’s Hospital, Leeds) the kits and selected foods were sent to four other units with similar interests in this condition (St Bartholomew’s Hospital, London, Western General Hospital, Edinburgh, Radcliffe Infirmary, Oxford, Bristol Royal Infirmary). Batches of food were purchased centrally by the Coeliac Society, divided into four, and sent to participating laboratories with a request that the kits be used on the foods according to the instructions, using equipment and other procedures as appropriate. The tests were performed by experienced laboratory technicians. There was no collusion between laboratories. The 24 foods could be divided into three groups. 4 gave clearly negative results in all four laboratories (gluten content 0’016%);
Goldenberg D, Simms R, Geiger A, Komaroff A. High frequency of fibromyalgia in patients with chronic fatigue seen in a primary care practice. Arthritis Rheum 1990,
33: 387-97. 2. Carette S, McCain G, Bell D, Fam A. Evaluation of amitriptyline in primary fibrositis a double-blind placebo controlled study Arthritis Rheum 1986, 29: 655-59 3 Goldenberg D, Felson D, Dinerman H. Randomised, controlled trial of amitriptyline and naproxen in treatment of patients with fibrositis. Arthritis Rheum 1986, 29: 1371-77. 4. Wessely S. Old wine in new bottles: neurasthenia and "ME" Psychol Med 1990; 20: 35-53.
SIR,-Mr Cox and his colleagues describe reduced concentrations of magnesium in red blood cells of patients with chronic fatigue syndrome and a response of such patients to magnesium supplementation. However, red cell magnesium is a poor indicator of body magnesium and does not correlate with the magnesium content of other cell types1,2 and it is at least partly genetically determined.3 Furthermore, magnesium concentrations are 3-4 times as high in reticulocytes as in mature cells and they decline with the age of cells.4 Cox et al are, therefore, unjustified in suggesting the presence of a significant magnesium deficit on the basis of this biochemical marker alone. More sensitive indicators of body magnesium status include muscle or monocyte magnesium levels and the intravenous magnesium loading test.5