[Measurement of colonic transit time (total and segmental) with radiopaque markers. National reference values obtained in 192 healthy subjects. Spanish Group for the Study of Digestive Motility].
The interest for the technique of colonic transit time (CTT) measurement with radiopaque markers has been limited in our ambience, despite its documented clinical usefulness in evaluating patients with severe chronic idiopathic constipation. The aim of the present study was to contribute to the development of the technique by establishing the upper limit of CTT in a large series of healthy subjects in order to be used as national reference. Total and segmental CTT have been determined in 192 healthy subjects (114 men, 78 women; median age: 33 yr; range: 18-88 yr) recruited in 18 hospitals of Spain. CTT measurement has been carried out by means of daily administration of 20 radiopaque markers during three consecutive days and plain abdominal X-ray taken at 4th, 7th and, eventually, 10th day. The upper limit (95th percentile) of total, right, left and rectosigmoid CTT was, respectively, 71.2, 22, 37.2 and 37.2 h. Women had significantly longer transits than men for whole (p = 0.002), right and rectosigmoid (p = 0.01, respectively) colon and near to statistical significance (p = 0.076) for left colon. In this series, CTT were not related to age and geographic area. Correlation between results obtained in the first reading of X-ray done in each center and a second reading done by an independent observer, was excellent (p < 0.001). CTT measurement with radiopaque markers is a simple technique, attainable to different assistance settings. The obtained values are proposed as national reference given their independence from geographic area. When employing the technique to clinical evaluation of patients with constipation, the differences of CTT in function of gender should be kept in mind.