DIAGNOSTIC-VALUE OF A GUAIAC OCCULT BLOOD-TEST AND FECAL ALPHA-1-ANTITRYPSIN

This study evaluates the diagnostic accuracy of a faecal occult blood test and faecal alpha 1-antitrypsin in the investigation of patients w ith gastrointestinal symptoms or iron deficiency anaemia. One hundred and seventy nine patients with either iron deficiency anaemia (n=67), changed bowel habit and aged >39 years (n=107), or a history suggestiv e of melaena (n=5) provided faecal samples. After investigation, 32 pa tients had a diagnosis of possible gastrointestinal bleeding and 139 p atients had no evidence of gastrointestinal bleeding. Eight patients h ad a cause of enteric protein loss in the absence of gastrointestinal bleeding and were excluded from subsequent analysis. The faecal alpha 1-antitrypsin test was diagnostically more accurate than the guaiac te st in identifying probable gastrointestinal bleeding (82% and 72% resp ectively, p<0.05). This faecal alpha 1-antitrypsin test was also more specific (83% and 72% respectively, p<0.05), but was not significantly more sensitive (78% and 72% respectively). The sensitivity of these t ests was insufficient to recommend their use for most patients in this study.