**5. Conclusion**

Iron metabolism is a dynamic process which cannot be defined by one laboratory test only. The analysis of these new parameters can be performed simultaneously in the course of

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**15**

*USA* 

**Exogenous Fluorescent Agents for the** 

Raghavan Rajagopalan and Richard B. Dorshow

*Covidien Pharmaceuticals, Hazelwood, Missouri,* 

**Determination of Glomerular Filtration Rate** 

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.

In order to assess the status and to follow the progress of renal disease, there is a need to develop a simple, accurate, and continuous method for the determination of renal function by non-invasive procedures. At present, endogenous serum creatinine (**1**) (Fig. 1) concentration measured at frequent intervals over a 24-hour period has been the most common method of assessing renal function despite the well known serious limitations.16-18 The results from this analysis are frequently misleading since the value is affected by age, state of hydration, renal perfusion, muscle mass, dietary intake, and many other anthropometric and clinical variables. Theoretical methods for estimating GFR (eGFR)19-21 from body cell mass and plasma creatinine concentration have also been developed, but these methods also rely on the above anthropomorphic variables. Moreover, creatinine is

**1. Introduction** 

who are at risk for renal impairment.13-15

**2. Current GFR markers** 

Zager, R.A., Johnson, A.C.M., Hanson, S.Y., & Wasse, H. (2002). Parenteral iron formulations: a comparative toxicologic analysis and mechanisms of cell injury. *American Journal of Kidney Disease* 40, 90-103.
