Effect of Lipemia on Measured and Calculated Osmolality in Native Lipemic Samples and Intravenous Lipid Emulsion-Added Pools
Introduction: Lipemia are common interferences in clinical laboratories. They particularly cause interference because of the electrolyte exclusion effect on indirect Ion Selective Electrodes (ISE) methodologies. This may produce falsely low Na and K values, thereby leading to pseudohyponatremia...
Main Authors: | , , , |
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Format: | Article |
Language: | English |
Published: |
JCDR Research and Publications Pvt. Ltd.
2020-01-01
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Series: | National Journal of Laboratory Medicine |
Subjects: | |
Online Access: | http://www.njlm.net/articles/PDF/2384/43186_CE[Ra1]_F(SHU)_PF1(AG_KM)_PFA(SHU)_PB(AG_SHU)_PN(SHU).pdf |
Summary: | Introduction: Lipemia are common interferences in clinical
laboratories. They particularly cause interference because
of the electrolyte exclusion effect on indirect Ion Selective
Electrodes (ISE) methodologies. This may produce falsely low
Na and K values, thereby leading to pseudohyponatremia and
pesudohypokalemia. However, the effect of lipemia on measured
Osmolality (mOSM) and calculated Osmolality (cOSM) remains
unknown.
Aim: To investigate the effect of lipemia on mOSM and cOSM
values in naturally lipemic samples of high concentration and
pools simulating lipemia according to different calculation
formulae.
Materials and Methods: In the first phase, serum samples of 55
patients with Triglyceride (TG) concentrations of >7.91 mmol/L
were collected from routine clinical care. The concentrations of
OSM, TG, Glucose (Glc), urea, Na, and K were measured before
and after high-speed centrifugation. OSM was measured with
a freezing-point depression osmometer. The 18 OSM formulae
that is applied was utilised for OSM calculations. In the second
phase, lipemia interference was assessed in Intravenous Lipid
Emulsion (IVLE) added sera.
Starting serum pools that had 0.95 mmol/L TG concentrations
were prepared from fresh-clear serum. Then, by mixing of one
unit of IVLE {Intralipid 20%, Clin Oleic (Baxter, Old Toongabbie,
NSW)} with 19 units of starting pool, the first pool was made.
This first pool with IVLE had an intralipid concentration of 10
g/L. The concentrations of OSM, TG, Glc, urea, Na, and K were
measured before and after IVLE addition. Statistical analyses
were performed using the Statistical Package for the Social
Sciences (SPSS®) for Windows, version 16.0 software (IBM,
Chicago, USA).
Results: In the first phase of study, there were no significant
differences in the mOSM concentrations between non-lipemia
and lipemia samples. However, there was a significant difference
between non-lipemia samples and lipemia samples for cOSM in
all formulae (p<0.001). Further, there was a significant difference
between mOSM and cOSM in the lipemia samples. There was
no significant difference between the cOSM of the lipemic
samples and mOSM of the non-lipemic samples according
to the F11 and F18 (p=0.651, p=0.841). In the second study
phase, although there was increased cOSM level dependent
on diminished TG concentrations in IVLE-supplemented pools,
mOSM levels were reduced.
Conclusion: This study demonstrated that lipemia does affect
the accuracy of cOSM. Lipemia does not affect mOSM when
performed with a freezing-point depression method. OSM
should not be calculated because of interference of lipemia. |
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ISSN: | 2277-8551 2455-6882 |