Point-of-Care Measurement of Serum Creatinine in the Intensive Care Unit

Abstract

Objective: To test the precision and limits of agreement of point-of-care testing (POCT)-based measurement of serum creatinine (Cr) in critically ill patients. Methods: We studied 250 paired blood samples from 82 critically ill patients from a general intensive care unit by simultaneous POCT and central laboratory testing (Jaffé method). Correlation, precision, bias, and limits of agreement were assessed. Possible confounders for interference of noncreatinine chromogens were evaluated by multivariate linear regression analysis. Results: The mean difference in serum Cr measured by central laboratory and POCT was +9.6 µmol/L (95% limits of agreement: −11.2 to +30.4 µmol/L). The mean percentage difference between the two techniques was 8.7% (95% limits of agreement −7.8% to +25.1%). On multivariate regression, the difference in serum Cr was increased with greater hemoglobin and lactate levels but decreased with greater bilirubin, albumin, and calcium levels. Conclusions: Compared with the central laboratory testing, POCT-based measurement of serum Cr in critically ill patients carried a small negative bias. This difference appeared affected by the blood levels of biochemical variables known to affect the Jaffé method. POCT-based Cr measurement appears sufficiently accurate for clinical use.

The nature and discriminatory value of urinary neutrophil gelatinase-associated lipocalin in critically ill patients at risk of acute kidney injury

“…Urine and blood for NGAL analysis were obtained for each patient on enrolment only. Serum creatinine as measured by point-of-care testing [28] at study inclusion was also documented.…”

Evaluation of a point‐of‐care serum creatinine measurement device and the impact on diagnosis of acute kidney injury in pediatric cardiac patients: A retrospective, single center study

“…Bloomed et al prospectively assessed a total of 183 pairs of samples for creatinine from 207 patients and showed that the mean difference was +0.018 mg/dL and that the 95% limit of agreement was ‐0.18 to 0.21 mg/dL. In another prospective cohort study, of 250 samples from 82 critically ill patients, the mean difference between serum creatinine measured by a central laboratory and that measured by POC testing was +0.11 mg/dL (95% limits of agreement: ‐0.13 to +0.34 mg/dL) . Skurup et al also measured creatinine concentrations, in a total of 104 serum samples, and assessed the performance of the creatinine sensor of an ABL blood gas analyzer .…”

“…In another prospective cohort study, of 250 samples from 82 critically ill patients, the mean difference between serum creatinine measured by a central laboratory and that measured by POC testing was +0.11 mg/dL (95% limits of agreement: -0.13 to +0.34 mg/dL). 14 been evaluated by using various POC devices in some studies, 15,16 there has been no study on the impact of measurements of creatinine by a blood gas analyzer, especially on the detection of AKI in patients.…”

Reduced urinary levels of angiotensin-converting enzyme 2 activity predict acute kidney injury in critically ill patients

“…Serum creatinine concentration was measured with our point-ofcare blood gas analyser (Radiometer ABL800, Radiometer Medical ApS, Copenhagen, Denmark). 30 If this measurement was missing, we used that measured by the Austin Health Department of Pathology.…”