Correction factors for estimating potassium concentrations in samples with in vitro hemolysis: a detriment to patient safety (original) (raw)
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International Journal of Research in Medical Sciences
Background: Potassium is one of the most commonly affected analytes in a hemolysed sample. Many formulae have been devised to predict the actual potassium in a hemolysed sample. This study was performed to compare the predicted potassium value in a hemolysed sample to that of potassium value in a non-hemolysed sample of the same patient.Methods: The hemolytic index (HI) derived equation from the paper by Dimeski et al was used to calculate potassium value in this study. A total of 99 paired samples were evaluated where the first sample in a pair was the hemolysed one and the other sample was a non-hemolysed one.Results: This study found that the potassium value in a sample and its respective HI have weak positive correlation. However, there was a statistically significant strong positive correlation between the estimated potassium of hemolysed sample to that of the potassium in the non-hemolysed sample.Conclusions: Hence, we conclude that it is feasible to use HI-derived equation to...
Correction and reporting of potassium results in haemolysed samples
Annals of Clinical Biochemistry, 2006
Background: Potassium is usually the most important analyte affected by in vitro haemolysis and the result obtained may falsely indicate or disguise a lifethreatening abnormality and so give rise to inappropriate treatment. The purpose of the study was to provide a solution to the problem of reporting potassium on haemolysed samples, taking into account both clinical needs and analytical concerns (inter-individual and inter-sample variability). Methods: Using a new procedure that mimics the collection process in an actual clinical setting, haemolysed samples were prepared from 41 volunteers with a range of inter-individual factors-haemoglobin 80-173 g/L, red blood cells 2.42-6.77 Â 10 12 /L, leucocytes 3.0-306 Â 10 9 /L and platelets 31-710 Â 10 9 /L-in order to develop a more accurate correction equation using a haemolytic index (HI) corresponding to g Hb/L in plasma. Results: The mean (range) potassium increase was 0.0036 mmol/L (0.0029-0.0053 mmol/L) per unit HI. The following equation was developed to estimate potassium increase per HI, in order to compensate approximately for potassium leakage in haemolysed samples: Corrected K þ ¼ Measured K þ À(HI Â 0.004). Conclusion: The balanced solution is this: instead of reporting the post-haemolysis corrected potassium result a qualitative comment is given, indicating the likely range of the potassium concentration. If the potassium result is in a critically low or high range, it is communicated promptly to the requesting clinician.
Laboratory Medicine, 2009
Hemolysis, or the rupture of the red blood cell membrane, causes the release of hemoglobin and other internal components into the surrounding fluid. It has long been recognized as a source of error in a variety of chemical analyses. 1 Hemolyzed specimens are a relatively frequent occurrence in laboratory practice, having a prevalence reported to be as high as 3.3% of all routine samples sent to a clinical laboratory and accounting for nearly 60% of rejected specimens. Hemolysis causes factitious hyperkalemia appearing to be approximately linearly dependent on the final concentration of blood cell lysate in the specimen. Some formulas, based on the relative distribution of potassium between serum and erythrocytes, have been proposed as a means of making a quantitative correction of the effect of hemolysis through measurements of serum hemoglobin. 4,5 These correction factors were obtained by multiplying the hemoglobin concentration by the slope obtained from a linear regression analysis between the bias observed for potassium at the relative free serum hemoglobin concentration. 4,6 Nevertheless, as reported in the literature, these factors are heterogeneous. This could be due to the complexity of preparing physiological hemolytic solutions to assess the inter-individual red cell hemoglobin concentration. Because the mean concentration of hemoglobin in the red cells differs among individuals, the quantity released into the serum as a result of hemolysis will also be different and is difficult to correlate to the total potassium released by means of a "common" correction factor.
Journal of Pharmacy and Pharmacology 5 (2017) 902-906, 2017
Hemolysis in ED (emergency department) patients is common due to difficult blood draws. Values of serum potassium (K +) become falsely elevated secondary to release of intracellular contents. Objective: The aim of the study was to establish a correction factor for factitious elevated K + in samples for de adult ED. Methods: We used samples from 125 adult ED patients, in which the 2nd sample was drawn due to hemolysis of the first tube. Results: Firstly, we derived a correction factor expressing an increase in potassium concentration in 0.21 mmol/L (95% confidence interval, 0.17-0.24 mmol/L with p < 0.01) for each hemolysis index increment. Conclusions: A reliable correction factor for factitious hyperkalemia in a clinical relevant range exists.
Journal of clinical laboratory analysis, 2015
The goal of this work was to determine if immediate versus postponed centrifugation of samples affects the levels of serum potassium. Twenty participants donated normal venous blood that was collected in four serum separator tubes per donor, each of which was analyzed at 0, 1, 2, or 4 hr on the Siemens Advia 1800 autoanalyzer. Coefficients of variation (CVs) for potassium levels ranged from 0% to 7.6% with a mean of 3 ± 2%. ANOVA testing of the means for all 20 samples showed a P-value of 0.72 (>0.05) indicating that there was no statistically significant difference between the means of the samples at the four time points. Sixteen samples were found to have CVs that were ≤5%. Two samples showed increases of potassium from the reference range to levels higher than the upper reference limit, one of which had a 4-hr value that was within the reference or normal range (3.5-5 mEq/l). Overall, most samples were found to have reproducible levels of serum potassium. Serum potassium level...
Haemodynamic consequences of changing potassium concentrations in haemodialysis fluids
BMC Nephrology, 2011
Background: A rapid decrease of serum potassium concentrations during haemodialysis produces a significant increase in blood pressure parameters at the end of the session, even if effects on intra-dialysis pressure are not seen. Paradoxically, in animal models potassium is a vasodilator and decreases myocardial contractility. The purpose of this trial is to study the precise haemodynamic consequences induced by acute changes in potassium concentration during haemodialysis. Methods: In 24 patients, 288 dialysis sessions, using a randomised single blind crossover design, we compared six dialysate sequences with different potassium profiles. The dialysis sessions were divided into 3 tertiles, casually modulating potassium concentration in the dialysate between the value normally used K and the two cut-off points K+1 and K-1 mmol/l. Haemodynamics were evaluated in a non-invasive manner using a finger beat-to-beat monitor.
Journal of Clinical & Experimental Nephrology, 2018
Background: Potassium abnormalities can cause lifethreatening arrhythmias. Measuring potassium requires access to blood. We have developed methods measuring potassium noninvasively using the processed, signalaveraged ECG. Four patients, in a larger study, were found to have unexpected discrepancies between measured blood potassium and ECG-derived estimated potassium values. Methods: Of 240 patients enrolled at 17 sites in the PORTEND (REVEAL-HD) study, 200 wore a continuouslyrecording, single-lead, wireless ECG patch. Blood for chemistries was obtained once before, twice during and once after dialysis. Complete blood test and ECG data were available for 142 subjects. The general potassium pattern during dialysis was an exponential decay throughout the treatment. Four subjects, whose blood potassium values, but not ECG-based potassium values, deviated from this pattern, are the subjects of this analysis. Findings: Among 4 patients, at least one blood potassium value declined to 2.6 mmol/l or less during dialysis, and then rebounded unexpectedly, while the ECG-based potassium values were consistent with the expected exponential delay. Three of these four patients were at a single site, suggesting site-specific likelihood of pattern deviation (p=0.04). In each case, BUN and phosphorous blood levels were markedly low, with albumin and calcium unaffected. Conclusions: These results are compatible with blood drawing errors in which dialyzed blood was obtained from the venous return, rather than from the arterial tubing. A physiologic, ECG-based test that estimates potassium on the basis of the concentration of potassium in the blood surrounding the heart is free from local aberrations and might be a useful potassium monitoring tool in dialysis patients.
Detection of haemolysis and reporting of potassium results in samples from neonates
Annals of Clinical Biochemistry, 2009
Background: In vitro haemolysis is a common occurrence in clinical laboratories and causes a spurious increase in potassium. In the past, haemolysis was sought by visual inspection but is now commonly detected by automated measurement of the haemolytic index (HI). This study compared detection of haemolysis in adult and neonatal samples by inspection and measurement of HI and verified that a single equation is appropriate to correct for the increase in potassium in both haemolysed samples. Methods: Laboratory staff inspected samples for haemolysis and their observations were compared with the measured HI. The potassium concentrations and haemolytic indices of 613 adult and 523 neonatal samples were correlated to derive equations to compensate for the increase in potassium with increase in HI. These were found not to differ significantly and a single equation for use in both populations was derived. Results: The presence of icterus was found to decrease ability to detect haemolysis on inspection. The mean (95% confidence limits) potassium increase per unit HI was 0.0094 mmol/L (0.0078-0.0103 mmol/L) for adults and 0.0108 mmol/L (0.0094-0.0121 mmol/L) for neonates. The equation developed to compensate for potassium release in haemolysed samples was: adjusted potassium ¼ measured potassium 2 (HI in mmol/L Â 0.01). Conclusion: The use of HI rather than visual inspection is particularly recommended in neonates whose serum tends to be icteric. It can be used in the same correction equation as in adults to compensate for potassium released due to haemolysis and facilitate reporting a qualitative comment to assist in immediate clinical management.
Indian Journal of Critical Care Medicine, 2019
The major extracellular electrolytes, sodium, and potassium are often requested together and form a large percentage of the requested tests in routine clinical chemistry laboratories. Two types of devices that use direct and indirect ion-selective electrode (ISE) methods are used in hospitals for electrolyte measurements: blood gas analyzers (BGA), which use direct ISE technology, and the indirect ISE method, which is often used in a central-laboratory autoanalyzer (AA). We aimed to summarize the current scientific knowledge based on whether the electrolyte test results, using Na and K test results obtained with BGA and an AA, can be used interchangeably. We searched Medline (PubMed), Google Scholar, and Web of Science up to 31 st March 2018. In addition, references of the included studies were also examined. Fourteen studies with a risk of bias were included in the analysis. Limits of agreement differences were variable among BGA and AA sodium and potassium test results in clinical practice. The results of both BGA and AA measures should not be used interchangeably under the assumption that they are equivalent to each other.
Scandinavian Journal of Clinical and Laboratory Investigation, 2019
The aim of this study was to examine the influence of hemolysis on 25 clinical chemistry parameters and to compare the resulting bias with clinically significant differences and the manufacturer's specifications. Using freeze-thawing of the treated blood aliquot of each subject (N ¼ 17), four hemolysis levels were prepared with hemolysis index (HI) and hemoglobin concentration as follows: (þ)¼0.5-0.99 g/ L, (2þ)¼1-1.99 g/L, (3þ)¼2-2.99 g/L and (4þ)¼3-4.99 g/L. All analytes were tested on the Beckman Coulter AU480 analyzer using proprietary reagents. It was considered that the interference was detected if the 95% confidence interval for mean differences (%) between hemolyzed and non-hemolyzed samples did not include zero. Clinically significant interference was judged against reference change value (RCV). Hemolysis interference was detected for: alpha-amylase, alkaline phosphatase (ALP), aspartate aminotransferase (AST), total and conjugated bilirubin, creatine kinase (CK), CK-MB, Ç-glutamyltransferase (GGT), iron, lactate dehydrogenase (LD), magnesium, potassium, total protein and uric acid at HI¼(1þ); alanine aminotransferase (ALT) and phosphate at HI¼(2þ); urea at HI¼(3þ); albumin and cholinesterase at HI¼(4þ). Even at the greatest hemolysis degree, HI¼(4þ), no interference was detected for calcium, chloride, creatinine, C-reactive protein (CRP), glucose and sodium. Clinically significant difference was exceeded for LD at HI¼(1þ); CK-MB at HI¼(2þ); AST and potassium at HI¼(3þ); total bilirubin at HI¼(4þ). The presented results did not support the manufacturer's claim for CK and GGT. Establishing HI thresholds for reporting or suppressing test results is the responsibility of each laboratory, taking into account the manufacturer's data, but also its own investigations.