[The clinical significance of pseudouridine determination of the urine in children and adolescents].

A HPLC-method is described to determine the Pseudouridine/creatinine ratio in spontaneous urine samples in infancy and childhood. The urines of 74 healthy children between 1 and 18 years of age and of 231 children with different diseases were examined for this ratio, making 1097 measurements. 157 children suffered from a malignant disease, 66 of them having an acute leukemia. Those patients, who remain in remission of the leukemia showed normal values, whereas the others had elevated ratios, reflecting the activity of the leukemia, when they were followed up by multiple determinations. Perhaps it is also possible to detect preclinical stages of leukemia by measuring the pseudouridine/creatinine ratio routinously over a long period of time. Today no strict correlation between the prognosis of leukemia and the level of this ratio can be drawn. Similar behaviour of the pseudouridine/creatinine ratio is seen in other malignant diseases with exception of brain tumors. The difference to leukemias is, that all other malignant tumors show more often normal values in patients with a remaining tumor. A pathological value of pseudouridine may also be seen in others than malignant diseases.