Normal colon transit time in healthy Chinese adults in Hong Kong

Background and Aim:  Colon transit study with radio-opaque markers is helpful in the evaluation of chronic constipation. Normal reference values, based on radio-opaque markers, have not been reported from Chinese adults in Hong Kong. Methods:  Fifty-one healthy Chinese (27 men, age 42 ± 12 years) were enrolled through a newspaper advertisement. They were requested to fill in detailed dietary records and a gastrointestinal symptom questionnaire. Each subject swallowed, under supervision, a total of three Sitzmarks capsules, one capsule at the same time on each of day 1, 2 and 3. Abdominal films were taken on days 4 and 7, also at the same time of the day. Total and segmental transit times were calculated using Metcalf's method. Results:  The upper limit of normal total colonic transit time (CTT) was 62 h, while right, left and rectosigmoid CTT were 16 h, 31 h and 32 h, respectively. Women of age 18–35 years had a longer rectosigmoid and total CTT compared with their male counterparts (mean total CTT: 39 h vs 18 h, P = 0.05). The CTT appeared to be unaffected by the usual dietary components. Conclusion:  A single normal reference value for CTT appeared to be applicable to Chinese adults in Hong Kong, irrespective of age, sex and dietary content. However, young Chinese women (age 18–35 years) appeared to have longer total and rectosigmoid CTT.