Increased gut parasympathetic activity and chronic diarrhoea in a patient with the acquired immunodeficiency syndrome

A 25-year-old homosexual man with a 2-year history of watery diarrhoea and a 20 kg weight loss is described. He had been diagnosed HIV-1 antibody positive 6 years previously. Investigations excluded opportunist pathogens and other known causes of diarrhoea. A range of anti-diarrhoeal medication had been unsuccessful. Plasma levels of gastrointestinal and pancreatic peptides were normal and treatment with the somatostatin analogue, octreotide, which inhibits release of pancreatic/gut peptides, did not provide any benefit. Cardiovascular autonomic function tests revealed blunted pressor responses but no other abnormalities. Gastric emptying studies with a technetium labelled meal indicated rapid gastric emptying time. This was slowed by the anticholinergic drug, atropine. This suggested increased parasympathetic activity to the gut. He was, therefore, treated with the anti-cholinergic agent, propantheline bromide, which reduced the frequency and volume of stools. He put on weight and has remained well since. This case highlights the diagnostic challenge in HIV-associated chronic diarrhoea, the case for investigations of autonomic function, and the need for a therapeutic trial of anticholinergic drugs, when other measures have failed.