Objective: Differential sugar absorption test with lactulose and mannitol is videly used for intestinal permeability investigation. The methods of choice for lactulose and mannitol determination in urine are GC and HPLC methods. At this time commercial enzymatic tests for this sugar determiantion in urine are available. We compared results of GC and enzymatic method. Methods: 17 urine samples from patients undergoing LAMA sugar absorption test were analysed by using of GC and enzymatic method for lactulose and mannitol determination. The results of these methods were compared by Passing- -Bablock regression method. Results: Passing-Bablock regression demostrates the presence of the proportional deviation, positive in case of mannitol (y = 1,1994x – 0,6512), and negative in case of lactulose (y = 0,8125x – 0,0382). Pathological increased intestinal permeability was established in 6 cases by GC method and in 5 cases by enzymatic emthod. Conclusions: The proportional deviation exists between GC and enzymatic method for lactulose and mannitol determination in urine. The diagnostic utility of both analytical methods was in our group of patients comparable.

        Key words: lactulose, mannitol, intestinal permeability, leaky gut syndrom