**1. Introduction**

250 Chronic Kidney Disease

Zager, R.A., Johnson, A.C.M., Hanson, S.Y., & Wasse, H. (2002). Parenteral iron

*American Journal of Kidney Disease* 40, 90-103.

formulations: a comparative toxicologic analysis and mechanisms of cell injury.

Glomerular filtration rate (GFR) is now widely accepted as the best indicator of renal function in the state of health and illness.1,2 Current clinical guidelines advocate its use in the staging of chronic kidney disease as well as in assessing the risk of kidney failure under acute clinical, physiological, and pathological conditions.3-6 Acute renal failure (ARF) is a major cause of complications in the post-surgical and post-intervention vascular and cardiac procedure patient populations. ARF is also a major public health issue because it may lead to chronic renal failure. Real-time, continuous monitoring of GFR in patients at the bedside is particularly important in the case of critically ill or injured patients, and those undergoing organ transplantation because most of these patients face the risk of multiple organ failure (MOF) resulting in death.7-10 MOF is a sequential failing of lung, liver, and kidneys and is incited by one or more severe causes such as acute lung injury (ALI), adult respiratory distress syndrome (ARDS), hypermetabolism, hypotension, persistent inflammation, or sepsis. The transition from early stages of trauma to clinical MOF is marked by the extent of liver and renal failure and a change in mortality risk from about 30% to about 50%.10 Accurate determination of GFR is also necessary for monitoring patients undergoing cancer chemotherapy with nephrotoxic anticancer drugs,11 or those at risk for contrast media induced nephropathy (CIN).12 Finally, GFR measurement is also useful for patients with chronic illness such as diabetes, hypertension, obesity, hyperthyroidism, cystic fibrosis, etc. who are at risk for renal impairment.13-15
