Related Experiment Video
Updated: May 17, 2025
A High-throughput Method for Measurement of Glomerular Filtration Rate in Conscious Mice
Published on: May 10, 2013
Determination of Glomerular Filtration Rate After Contrast-Enhanced CT Among Critically Ill Patients: Support for a
Bertil Kågedal1, Anders Helldén1,2, Dženeta Nezirević Dernroth1
1Department of Biomedical and Clinical Science, Division of Clinical Chemistry and Clinical Pharmacology, Linköping University, Linköping, Sweden.
Objectives:
To measure glomerular filtration rate using iohexol plasma clearance (mGFRiohexol) in critically ill patients using the high doses of iohexol administered at CT and to evaluate its agreements with urinary creatinine clearance (uClcr) and estimated glomerular filtration rates (eGFRs), calculated from plasma concentrations of creatinine (eGFRcr) and cystatin C (eGFRcys).
Design:
Prospective observational cohort study.
Setting:
ICUs across Southeast Sweden.
Patients:
Critically ill adult patients.
Interventions And Measurements:
Twenty-six ICU patients were given high doses of iohexol (range, 27-140 mL) for contrast-enhanced CT, whereafter blood samples were taken in the elimination phase for determination of mGFRiohexol. Plasma iohexol concentrations were determined by high-performance liquid chromatography and mGFRiohexol was calculated. Standard dose (5 mL) of iohexol was administered the following days to compare low-dose clearance results with the high-dose clearance results. Six-hour uClcr was performed four times a day and averaged.
Main Results:
Mean ± sd mGFRiohexol after CT was 77.4 ± 38.1 mL/min (n = 26), and uClcr was 97.3 ± 58.2 mL/min (n = 25) in the critically ill patients. There was a strong positive correlation between mGFRiohexol determined with high and low doses of iohexol in patients with normal or high mGFRiohexol (coefficient of determination [R2] = 0.88; p < 0.001) and between mGFRiohexol and uClcr (R2 = 0.87; p < 0.001). eGFRcr overestimated mGFRiohexol and eGFRcys underestimated mGFRiohexol.
Conclusions:
mGFRiohexol after contrast-enhanced CT compares well with mGFRiohexol after standard low-dose iohexol respectively uClcr. Over- and underestimation of mGFRiohexol by eGFRcr and eGFRcys is probably explained by increased tubular secretion of creatinine and increased production of cystatin C in intensive care patients.
Related Concept Videos
01:30Radiological Investigation I: X-ray and CT
01:23Renal Clearance
Renal clearance refers to the volume of plasma cleared of a specific substance, such as creatinine, per unit of time. To measure clearance, urine samples are collected over a 24-hour period during each bladder voiding, followed by a single blood sample at the...
01:14Imaging Studies I: CT and MRI
Description of the Procedures
Computed Tomography (CT) scan:
Computed Tomography (CT) scans use X-ray technology to generate detailed images of bones, organs, and tissues. During the scan, the patient lies on a moving table...
01:17Factors Affecting Renal Clearance: Renal Impairment
One condition associated with renal failure is uremia. Uremia is characterized by impaired glomerular filtration and fluid accumulation in the body. This condition hinders the renal clearance of drugs, resulting in drug accumulation and potential...
01:02Renal Drug Excretion: Glomerular Filtration
Drugs gain access to the kidney via the renal artery, which progressively branches off into afferent arterioles....
01:07Determination of Renal Drug Clearance: Graphical and Midpoint Methods
The graphical method involves plotting the rate of drug excretion in urine against the plasma drug concentration. By analyzing the graph, the clearance can be calculated and obtained. Drugs rapidly excreted by the kidneys exhibit a...