Circadian rhythm of plasma and urinary angiotensinogen in healthy volunteers and in patients with chronic kidney disease

The urinary angiotensinogen (AGT) excretion rate could be a novel biomarker for the intrarenal activity of the reninangiotensin system. Little is known about the circadian rhythm of AGT levels in plasma or urine. In this short article, making use of data in plasma and urine of healthy volunteers and patients with chronic kidney diseases, we first report that we were unable to find evidence for a circadian rhythm of AGT under any condition. Next we critically discuss to what degree elevated urinary AGT levels might be considered an independent biomarker that is not simply the nonspecific consequence of proteinuria.