Introduction: Chronic kidney disease (CKD) carries a lot of co-morbidities. Urea rise may be related to decline in glomerular filtration rate, under nutrition or hyper catabolic state. According to urea percentile curves (UPC), patients with a given glomerular filtration rate show wide range of urea levels.  Correlation between urea percentiles and CKD patients' co-morbidities was suggested in many studies since Montini 2003. 
Aim of the study: to evaluate the value of UPCs as a simple tool in monitoring metabolic status and progress of CKD comorbidities.
Methods: Retrospective revision of patients' files for their urea levels and GFR at the time of diagnosis and long period after (follow-up). Accordingly, each patient was plotted on UPC graph to determine his urea percentile (UP) at each setting. Patients were classified according to their urea percentile as low, moderate and high UP groups, and classified according to urea percentile progress pattern as ascending, descending and stable groups. Correlations between their co-morbidities and their urea percentiles were statistically analysed.
Results: showed correlation between morbidity markers changes in relation to progress course of UP with significant differences in the values of phosphorus rise, bicarbonate changes and frequency of hyperphosphatemia between the 3 groups of urea percentile progress pattern.
Conclusion: Follow up pattern of urea percentile in these children is a simple and helpful tool in monitoring their co-morbidities.