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Glomerular filtration rate measurement in cirrhotic patients with renal failure
L Roy1, L Legault, G Pomier-Layrargues
1Nephrology Unit, Research Center, hospitalier de l'Université de Montréal, Quebec, Canada.
Insights
Renal creatinine clearance overestimates glomerular filtration rate (GFR) in cirrhotic patients, similar to chronic renal failure patients. This overestimation is solely due to the severity of renal failure, not specific to liver disease.
Area of Science:
- Nephrology
- Hepatology
- Clinical Chemistry
Background:
- Assessing glomerular filtration rate (GFR) in cirrhotic patients is crucial for patient management.
- Renal creatinine clearance is a common but potentially inaccurate method for GFR estimation in liver disease.
- Understanding GFR misinterpretation in cirrhotics with renal failure is essential.
Purpose of the Study:
- To investigate the accuracy of renal creatinine clearance in estimating GFR in cirrhotic patients with varying degrees of renal dysfunction.
- To compare GFR overestimation by renal creatinine clearance in cirrhotic versus non-cirrhotic chronic renal failure (CRF) patients.
- To determine if liver disease itself alters renal creatinine excretion.
Main Methods:
- Simultaneous measurement of inulin clearance (gold standard for GFR), PAH clearance, and renal creatinine clearance.
- Study included 30 cirrhotic patients with renal failure and 5 non-cirrhotic CRF patients.
- Measurements performed during a 4-hour inulin/PAH infusion and a 24-hour urine collection.
Main Results:
- In moderate to severe renal failure (inulin clearance ~30 ml/min), renal creatinine clearance overestimated GFR in both cirrhotic (ratio 1.8) and CRF patients (ratio 1.6).
- Cirrhotic patients exhibited lower serum creatinine levels (186 vs 133 micromol/l) despite similar GFR overestimation.
- In mild renal dysfunction (inulin clearance ~74 ml/min), renal creatinine clearance was only slightly overestimated (77 ml/min) in cirrhotic patients.
Conclusions:
- The degree of renal failure, not the presence of liver disease, explains the overestimation of GFR by renal creatinine clearance in cirrhotic patients.
- There is no evidence of specific alterations in renal creatinine excretion in cirrhotic patients.
- Renal creatinine clearance accuracy for GFR estimation is compromised in renal failure, irrespective of the underlying cause.
Abstract:
Assessment of renal function, namely glomerular filtration rate (GFR), by the renal creatinine clearance, may be problematic and less accurate in cirrhotics; however, it is an essential element in the global evaluation of these patients. In order to better characterize misinterpretation of GFR by the renal creatinine clearance, we compared a group of cirrhotic patients with renal failure (n - 30) to a group of chronic renal failure patients (CRF) without liver disease (n - 5). Inulin and PAH clearances were measured during a 4-hour infusion of inulin and PAH; renal creatinine clearance was measured during a 24-hour urine collection and this, simultaneously with inulin and PAH clearance. We observed that in moderate to severe renal failure (renal inulin clearance 30 +/- 10 ml/min), GFR (i. e. renal inulin clearance) in cirrhotic patients was overestimated by the renal creatinine clearance, similarly to CRF patients (ratio 1.8 +/- 0.7 and 1.6 +/- 0.9 respectively); however cirrhotic patients have a lower serum creatinine (186 +/- 97 vs 133 +/- 62 micromol/l respectively). On the other hand, cirrhotic patients with mild renal dysfunction (renal inulin clearance 74 +/- 15 ml/min) had a renal creatinine clearance of 77 +/- 25 ml/min. Systemic inulin clearance overestimated renal inulin clearance, proportionally to the severity of renal dysfunction. We conclude that it is only the degree of renal failure, irrespective of etiology, that explains the overestimation of the glomerular filtration rate by the renal creatinine clearance in cirrhotic patients; hence, there is no specific alteration in the renal excretion of creatinine in cirrhotic patients.