Microalbuminuria in inflammatory bowel diseases using immunoturbidimetry and high-performance liquid chromatography.

Background And Study Aims: To measure urinary albumin excretion using immunoturbidimetry (IT) and high-performance liquid chromatography (HPLC) in inflammatory bowel diseases.

Patients And Methods: A cross-sectional study was carried out on 60 selected patients with Crohn's disease (CD), 57 with ulcerative colitis (UC) and 22 healthy volunteers, as controls. Urinary albumin excretion was measured by IT and HPLC, and albumin-creatinine ratio was calculated. This ratio was compared in patients with active and inactive CD and UC and in healthy volunteers.

Results: Patients with CD and UC had higher albumin-creatinine ratio compared to controls using both IT and HPLC (p < 0.05). We measured higher albumin-creatinine ratio in patients with active compared to inactive CD (p < 0.05). Albuminuria did not correlate with disease duration of CD or UC, but patients with more extended CD according to the Montreal classification had higher HPLC-albumin-creatinine ratio. In CD, we found a significant correlation between HPLC-albumin-creatinine ratio and some inflammatory markers i.e. white blood cells (p < 0.05) and erythrocyte sedimentation rate (p < 0.05). In UC, there was no significant correlation between HPLC-albumin-creatinine ratio and the above markers of systemic inflammation or activity of UC. Albumin-creatinine ratio measured by HPLC was higher in both active and inactive CD and UC groups than albumin-creatinine ratio measured by IT. Using a receiver operating characteristics curve analysis, in case of HPLC-albumin-creatinine ratio cut-off values of the activity of CD were 2.46 mg/mmol for men, 5.30 mg/mmol for women.

Conclusions: HPLC-urinary albumin-creatinine ratio is associated with the clinical and laboratory disease activity indices in CD, but not in UC. Using HPLC we found a more sensitive method compared to IT to measure albuminuria that would be a sensitive activity marker in CD.