The majority of patients in a Swedish university hospital intensive care unit have reduced glomerular filtration rate measured by Cystatin C

Introduction

Renal dysfunction is associated with increased morbidity and mortality in intensive care patients. The aim of this study was to investigate the use of laboratory markers in an ICU, especially glomerular filtration rate (GFR) markers, and to compare two GFR markers, creatinine and Cystatin C. A secondary aim was to assess the frequency of reduced GFR in this patient group using the creatinine and Cystatin C estimated GFRs as several pharmaceuticals are prescribed according to renal function.

Methods

A retrospective observational study was performed in a general ICU at a Swedish university hospital. All adult patients treated at the ICU during 2004–2006 were included. Reduced kidney function was defined as ≤80 ml/min/1.73 m².

Results

GFR markers are frequently ordered in the ICU. The majority of the patients had a reduced kidney function as evaluated by Cystatin C and/or p-creatinine. A total 92.1% of the patient test results had Cystatin C estimated GFR (eGFR) ≤ 80 ml/min/1.73 m², 75.3% had eGFR ≤ 50 ml/min/1.73 m² and 30.4% had eGFR ≤ 20 ml/min/1.73 m². In contrast, only 46% of the patients had reduced renal function assessed by plasma creatinine.

Conclusion

The GFR is commonly assessed in the ICU. Cystatin C is a more sensitive GFR marker than creatinine. A majority of the ICU patients had a reduced GFR. Many of the pharmaceuticals used in the ICU are cleared by the glomeruli. It is thus important to monitor kidney function regularly, using an adequate assay. When possible, drugs with a plasma concentration that is less influenced by the GFR should be used.