Interference with Creatinine Assay by IgM-λ Monoclonal Protein in Lithium Heparin Blood Collection Tube from a Malignant Lymphoma Patient
Nobuyasu Yukimasa *
Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Takamatsu, Kagawa, Japan.
Wataru Oboshi
Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Takamatsu, Kagawa, Japan.
Keisuke Hayashi
Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Takamatsu, Kagawa, Japan.
Hiroko Kuribayashi
Clinical Laboratory, Showa University Northern Yokohama Hospital, Yokohama, Kanagawa, Japan.
Ryuichi Uzawa
Department of Pathology, Showa University Hospital, Tokyo, Japan.
Kunihiko Fukuchi
Department of Pathology, Showa University Hospital, Tokyo, Japan.
Takehiro Nakamura *
Department of Medical Technology, Kagawa Prefectural University of Health Sciences, Takamatsu, Kagawa, Japan.
*Author to whom correspondence should be addressed.
Abstract
Aims: Analytical interference in the clinical laboratory is a well-known phenomenon. When analyzing samples containing monoclonal immunoglobulins (M proteins), various problems could be encountered in the clinical laboratory data.
Presentation of Case: The authors report a patient with false elevated plasma creatinine concentration due to interference of monoclonal IgM in a routine test for creatinine determination. In the present case the interference might be caused by M protein precipitation, due to an increased turbidity and an apparent increase of absorbance in the clinical chemistry creatinine assay. Sia water test can provide a first clue to M protein aggregation; confirmation can be obtained by observing the time/absorbance curves of the analysis. When a Sia water test was performed with changes in the salt concentration, protein aggregation occurred at a higher salt concentration for the lithium (Li)-heparin plasma sample than the serum.
Discussion and Conclusion: These results suggested that the M protein of this patient, when interacted with Li-heparin, is more readily insolubilized. Subsequently, a reaction reproduction experiment was performed by adding the M protein component roughly purified to Li-heparin blood collection tubes. These results might support the aggregation of the M protein of this patient in the reaction solution due to its interaction with Li-heparin.
Keywords: Creatinine measurement, lithium (Li)-heparin plasma, monoclonal immunoglobulin (M protein), Sia water test.