Urinary Excretion of a Metabolite of Histamine (1,4‐methyl‐imidazole‐acetic‐acid) in Painful Bladder Disease

Summary— Thirteen patients with interstitial cystitis (detrusor mastocytosis) and 12 other patients with painful bladder disease without mastocytosis collected 24-h urine specimens that were analysed for the major metabolite of histamine, 1,4-methyl-imidazole-acetic-acid (1,4-MIAA), by reversed phase ion-pair high performance liquid chromatography. The median urinary excretion of 1,4-MIAA was 3.34 mg/24 h (range 1.47–4.66) in the patients with detrusor mastocytosis and 1.75 mg/24 h (range 0.18–4.30) in the other patients with a painful bladder (P<0.01). It was concluded from this study that patients with a painful bladder and detrusor mastocytosis had a significantly elevated urinary excretion of 1,4-MIAA compared with other painful bladder patients without mastocytosis, whose urinary excretion of 1,4-MIAA was within the normal range (0.72–2.34 mg/24 h). We suggest that the urinary excretion of 1,4-MIAA might be useful in the diagnosis of interstitial cystitis.