SERUM AND URINARY ANGIOTENSINOGEN IN CHILDREN WITH CHRONIC KIDNEY DISEASE

Abstract

Chronic kidney disease (CKD) occurs when there is significant and irreversible injury of the renal parenchyma. It is associated in children with an increased risk of impaired growth, anaemia, bone disease, cardiovascular disease and progression to end-stage renal disease. The challenge that faces a pediatric nephrologist, in such patients, is to slow down the progression of the disease and prevent the co-morbidities. This requires a better understanding of the causes and mechanisms of progression, as well as reliable markers for early detection of this progression. Some animal experimental studies suggest that the systemic renin-angiotensin system (RAS) plays a central role in the progression of CKD. Urinary angiotensin II is unstable and, therefore, cannot be used as a marker of intrarenal RAS activity clinically. On the other hand, urinary angiotensinogen level was highly correlated with intrarenal angiotensinogen and angiotensin II levels and has been introduced as a reliable marker for intrarenal RAS activity The aim of this work was to evaluate serum and urinary levels of angiotensinogen in children with CKD and to correlate these levels to the extent of renal impairment in those children. METHODS: This study was carried out in Pediatric Conservative Nephrology clinic, Children’s Hospital, Ain Shams University. It included 45 children, 35 patients with chronic kidney disease and 10 age & sex matched healthy children serving as control group. Cases had a glomerular filtration rate (GFR) between 60 ml/min/1.73 sq.mand 15 ml/min/1.73 sq.m & a duration of the disease not less than 6 months. They were 29 males & 6 females and their ages ranged from 1 year up to 14 years with mean age of 5.1 63.3 years. All patients were subjected to detailed history taking, thorough physical examination with special emphasis on blood pressure measurement, weight and height. Lab investigations included complete blood count (cbc) , serum creatinine and corrected creatinine clearance. Serum and urinary angiotensinogen were measured for each patient enrolled in the study as well as the control group. RESULTS: Urinary angiotensinogen (AGT) excretion as well as serum levels were significantly higher in children with CKD compared to controls. No significant difference was found between male and female cases in urinary and serum levels of AGT as well as between different etiologies of CKD. Normotensive and hypertensive cases were not significantly different in urinary and serum levels of angiotensinogen. Lastly CKD stages III and IV were not significantly different in serum and urinary levels of AGT. Urinary AGT was significantly & inversely correlated with eGFR (r¼ -0.93 , p < 0.001). Serum AGT was significantly & inversely correlated with eGFR (r¼-0.57 , p <0.001). CONCLUSIONS: urinary angiotensinogen, which is obviously actively excreted in urine (urinary levels are higher than serum levels), can be used as a marker of progression of CKD especially that it doesn’t seem to be affected by the gender or blood pressure or eitiology of CKD or its stage. The findings of our study is an additional emphasis on the importance of controlling RAS system activity to prevent progression of CKD in children. Nephrology Dialysis Transplantation Abstracts