URINARY EXCRETION OF N-METHYLHISTAMINE AS A MARKER OF DISEASE ACTIVITY IN IBD
- URINARY EXCRETION OF N-METHYLHISTAMINE AS A MARKER OF DISEASE ACTIVITY IN
Mast cells are thought to participate in the pathogenesis of inflammatory
bowel disease (IBD). In this study, urinary excretion of N-methylhistamine
(UMH), a stable metabolite of the mast cell mediator histamine, was
evaluated as an indicator of disease activity in patients with IBD.
Urinary excretion of UMH (?g/mmol creatinine � m2 body surface area) was
measured by radioimmunoassay in 55 controls, 56 patients with Crohn�s
disease, and in 36 patients with ulcerative colitis. Excretion rates were
correlated with clinical, serological, and endoscopic disease activity,
disease extent, and location.
Urinary excretion of UMH was found to be significantly elevated in IBD.
Patients with active Crohn�s disease (7.1 � 4.2, p = 0.002 vs controls) and
active ulcerative colitis (8.1 � 4.8, p = 0.02 vs controls) had higher rates
of UMH excretion than patients in remission (6.3 � 3.8 and 5.2 � 2.3,
respectively) or controls (4.6 � 1.9). In Crohn�s disease and ulcerative
colitis, a significant correlation of UMH excretion with clinical disease
activity was obtained (Crohn�s Disease Activity Index r2 = 0.58, Clinical
Activity Index r2 = 0.57, p < 0.0001). Serologically, orosomucoid showed the
best positive correlation with disease activity (Crohn�s Disease Activity
Index r2 = 0.80, Clinical Activity Index r2 = 0.86, p < 0.0001), but UMH
excretion was found to reflect disease activity more accurately than
C-reactive protein (Crohn�s Disease Activity Index r2 = 0.46, Clinical
Activity Index r2 = 0.42, p < 0.0001). No association between UMH excretion
and disease type or localization could be found in Crohn�s disease. However,
UMH excretion correlated strongly with endoscopic severity of inflammation
in Crohn�s disease (Crohn�s Disease Endoscopic Index of Severity r2 = 0.70,
p < 0.0001) or disease extent in ulcerative colitis.
Urinary excretion of the histamine metabolite UMH is enhanced in IBD. It appears to represent an integrative parameter to monitor clinical and endoscopic disease activity in IBD, which appears to be influenced most likely by mediators released from histamine-containing cells, such as intestinal mast cell subtypes.