- 作者：Jeanne M. Rhea ; James C. Ritchie ; Ross J. Molinaro ; rjmolin@emory.edu
- 关键词：Glomerular filtration rate ; Iothalamate ; Kidney donation ; Mass spectrometry
- 刊名：Clinica Chimica Acta
- 出版年：2013
- 出版时间：May, 2013
- 年：2013
- 卷：420
- 期：Complete
- 页码：104-108
- 全文大小：451 K
Background
Chronic kidney disease often goes undetected due to the insensitivity of current methods to accurately assess glomerular filtration rate (GFR) in early stages of renal dysfunction. The clearance of exogenously introduced iothalamate, a commonly used radiopaque agent, is an alternative to inulin clearance for the assessment of renal function and its use in calculating GFR can serve as a screening tool for kidney transplant donors.Methods
A method was developed to measure iothalamate in plasma and urine samples by HPLC combined with electrospray positive ionization tandem mass spectrometry (MS/MS). Iothalamate is isolated from plasma by methanol extraction and urine using a quick-spin filtration approach, then monitored by multiple reaction monitoring using the hydrogen adduct mass transitions. Iohexol was used as an internal standard.
Results
Iothalamate was measured within an analytical run time of 5 min, with a lower limit of quantification of 18.75 ng/ml. The intraassay and interassay variations of the plasma and urine iothalamate assays were both < 9 % . Recovery from plasma and urine samples ranged from 93.6 % to 104.1 % . GFR was calculated using the patient's urine flow rate and plasma and urine iothalamate values. Linear correlations tested by LC-MS/MS and an accepted capillary electrophoresis (CE) assay showed similar results (GFR, r = 0.92, Sy/x = 10.3).
Conclusions
We developed and validated an LC-MS/MS method for quantitating iothalamate in plasma and urine to calculate GFR used for screening potential kidney donors in our hospital system. A less sensitive mass spectrometry system does not sacrifice analytical or clinical sensitivity for measuring GFR.