Haemoglobin in gut lavage fluid as a measure of gastrointestinal blood loss.

To detect and measure occult gastrointestinal bleeding, we have measured haemoglobin concentrations (by HemoQuant) in the clear fluid obtained after whole-gut lavage. In subjects with healthy gastrointestinal tracts, lavage-fluid haemoglobin concentrations were 0.5-5.1 mg/L, equivalent to daily blood loss of 0.1-1.1 mL. High concentrations were found for patients with colorectal cancer, severe diverticular disease, and rectal varices, in seven of sixteen patients with active inflammatory bowel disease, and in four patients with iron-deficiency anaemia thought to be due to gastrointestinal bleeding. In these four patients, estimated blood loss ranged from 2.6-24.5 mL per day. This method could have various research and clinical applications.