Chronic diarrhoea

I read with interest the report by Gupta and colleagues (JRSM 2007;100:379) on their patient with chronic diarrhoea, a common clinical problem. They finally established that their patient had a rare disease, medullary thyroid carcinoma, and appropriate treatment was instituted. We are not told of the outcome, but hope that she did well.

Two lessons may be derived from this paper. First, after a battery of expensive laboratory investigations, together with sophisticated imaging and invasive endoscopies, it was subsequently found that there was a diffusely enlarged thyroid with enlarged lymph nodes. The important word here is ‘subsequently’ because an initial examination of the patient, using no more than eyes, ears and hands, should have revealed this elementary physical sign, thus saving a great deal of discomfort, time and money and determining an earlier treatment policy. The second lesson concerns the mention of ‘mesenteric ischaemia’ as a cause of chronic diarrhoea. ‘Intestinal ischaemia’ is a preferable term, as it is the intestine and not the mesentery that is ischaemic, but apart from that the statement is erroneous. There is not the slightest evidence that chronic ischaemia causes diarrhoea. The list of causes is lifted verbatim from an earlier review2 but that paper in turn provides no support for the assertion. One wonders where it came from.

The principle is important. It is all too easy to compound mistakes by the uncritical acceptance of inherited wrong ideas.