GASTROINTESTINAL BLOOD-LOSS AFTER NONSTEROIDAL ANTIINFLAMMATORY DRUGS - MEASUREMENT BY SELECTIVE DETERMINATION OF FECAL PORPHYRINS

1 A method for the detection of gastrointestinal blood loss based upon the selective measurement of faecal porphyrins was tested in two studies in healthy volunteers. 2 In the first study subjects (n = 6) received intragastric autologous blood (saline, 2 and 6 ml as a single dose) resulting in a dose dependent increase in faecal porphyrins. 3 In a subsequent placebo controlled cross over study in 12 subjects acetylsalicylic acid (ASA), nabumetone (a new NSAID) or placebo were administered for 5 days with a washout period of 9 days. They were no dietary restrictions. 4 All faeces were collected during the treatment period and both the full faecal homogenate and a random faecal sample were analyzed for deutero- and pemptoporphyrin content by h.p.l.c. Additionally a benzidine reaction was performed. 5 There was a highly significant correlation (r = 0.95) between the values obtained from random samples and the full homogenate. ASA increased the faecal porphyrin excretion (P < 0. 001) compared with placebo in contrast to nabumetone. Complaints of dyspepsia were most common after ASA. 6 Measurement of faecal porphyrins is useful for monitoring NSAID induced upper gastrointestinal blood loss and lacks some of the practical constraints of other methods.