Influence of hemolysis on clinical chemistry parameters determined with Beckman Coulter tests - detection of clinically significant interference

Increase of serum pancreatic enzymes during hospitalization for acute heart failure

AIMS

Acute heart failure (AHF) is associated with end-organ dysfunction. The effect of AHF on the pancreas has not been studied. We aim to evaluate serum markers of pancreatic damage during hospitalization for AHF.

METHODS AND RESULTS

In data from the Pragmatic Urinary Sodium-based treatment algoritHm in Acute Heart Failure (PUSH-AHF) study, amylase and lipase values were extracted from available serum samples at baseline, and at 24 and 72 h after hospitalization. The differences between pancreatic enzymes between timepoints were evaluated using the Friedman test. Associations with N-terminal pro-B-type natriuretic peptide (NT-proBNP) were tested using linear regression analysis. The study population consisted of 274 patients. Mean age was 73 ± 11 years, and 117 (43%) were women. Mean left ventricular ejection fraction (LVEF) was 38 ± 14%; 53 (19%) patients had HF with a preserved LVEF (≥50%). At baseline, median amylase and lipase were within normal range (47 [33-63] U/L and 30 [21-44] U/L, respectively). Both enzymes significantly increased in the first 72 h (P-value for trend <0.001); mean change was 9 ± 22 U/L for amylase, and 10 ± 22 U/L for lipase. Moreover, NT-proBNP at baseline showed a positive correlation with mean change in pancreatic enzymes in 72 h (P = 0.02 for amylase and P = 0.006 for lipase).

CONCLUSION

Patients admitted for AHF exhibited a significant increase in serum values of pancreatic enzymes in the first 72 h, suggesting that an episode of AHF affects the pancreatic tissue. This rise in pancreatic enzymes was associated with HF severity, as reflected by NT-proBNP.

Use of finer needles for venipuncture increases in vitro haemolysis despite reducing persistent pain and nerve injury: A retrospective study

BACKGROUND

Although venipuncture is minimally invasive, and is the most frequently performed medical procedure, it carries the small risk of causing persistent pain, including nerve damage. Recently, our hospital stopped using 22-gauge needles for venipuncture in outpatients and switched to using only 23- and 25-gauge needles. We investigated the impact of using only the finer needles on the incidence of persistent or neuropathic pain and the prevalence of haemolysis, as well as the impact of haemolysis associated with the needle change on other laboratory data.

METHODS

We retrospectively collected and analysed data on venipuncture-associated pain complaints made during the 1-year period prior and 1-year period after the change in needles, as well as the frequency of haemolysis before and after the change. We also focused on 90 cases that showed significant haemolysis after the needle change and compared the serum aspartate aminotransferase, lactate dehydrogenase, and potassium levels before and after the needle change.

RESULTS

The incidence of persistent pain was significantly reduced from 1 in 10,825 venipunctures before the change to 1 in 29,747 venipunctures after the change. Notably, no patients experienced neuropathic pain after the change. However, the prevalence of haemolysis was significantly increased. Additionally, the serum aspartate aminotransferase, lactate dehydrogenase, and potassium levels were significantly elevated in the cases that showed moderate to gross haemolysis after the needle change.

CONCLUSION

Using finer needles involves both advantages and disadvantages, and careful consideration is needed to determine which type of needle is in the best interests of the patient.

Predictive value of CD4+CD8+ double positive T cells for the severity of hemorrhagic fever with renal syndrome

PURPOSES

We aimed to investigate the levels of CD4+CD8+ double positive (DP) T cells in patients with various severities of hemorrhagic fever with renal syndrome (HFRS), and the predictive capacity of DP T cells for the severity of this disorder.

METHODS

The levels of DP T cells in 213 patients and 48 healthy donors were measured by flow cytometry, as were the levels of CD4+ T cells, CD8+ T cells, B lymphocytes, and natural killer (NK) cells. In each type of HFRS patient, we tested the basic clinical reference values for leukocytes, platelets, creatinine (Cr), uric acid (UA), and urea, and the values for activated partial thromboplastin time, prothrombin time, and fibrinogen, using conventional methods. The colloidal gold method was used to measure HFRS antibody levels in the patients.

RESULTS

The frequency of DP T cells increased with disease severity and peaked in patients with critical disease. Furthermore, the level of DP T cells proportionally correlated with the levels of Cr, UA, and urea in the serum. In contrast, there was an inverse correlation between DP T cells and platelets. Interestingly, the pattern of change in DP T cell frequency was similar to those of CD8+ T cells, B cells, and NK cells, but an inverse tendency was observed for CD4+ T cells. DP T cells demonstrated significant predictive value for the severity of HFRS.

CONCLUSIONS

The level of DP T cells is associated with HFRS severity, suggesting that it may be a potent indicator for the course of this disorder.

Hemolysis Control in the Emergency Department by Interventional Blood Sampling

The hemolysis rate in the emergency department (ED) is higher compared to that in other departments. We propose a new blood sampling technique without repeated venipuncture to reduce hemolysis and compare the hemolysis rate between blood collected by this method and that collected with an intravenous (IV) catheter. This prospective study included a nonconsecutive sample of patients visiting the ED (aged ≥ 18 years) of a tertiary urban university hospital. The intravenous catheterization was performed by three pre-trained nurses. The new blood collection technique involved sample collection without removing the catheter needle, performed immediately before the conventional method (through an IV catheter), without additional venipuncture. Two blood samples were collected from each patient using both the new and conventional methods, and the hemolysis index was evaluated. We compared the hemolysis rate between the two methods. From the 260 patients enrolled in this study, 147 (56.5%) were male, and the mean age was 58.3 years. The hemolysis rate of the new blood collection method was 1.9% (5/260), which was significantly lower than that of the conventional method (7.3%; 19/260) (p = 0.001). The new blood collection method can reduce the hemolysis rate as compared to the conventional blood collection method.

Instrument-free single-step direct estimation of the plasma glucose level from one drop of blood using smartphone-interfaced analytics on a paper strip

We demonstrated an instrument-free miniaturized adaptation of the laboratory gold standard methodology for the direct estimation of plasma glucose from a drop of whole blood using a low-cost single-user-step paper-strip sensor interfaced with a smartphone. Unlike a majority of the existing glucose meters that use whole blood-based indirect sensing technologies, our direct adaptation of the gold-standard laboratory benchmark could eliminate the possibilities of cross interference with other analytes present in the whole blood by facilitating an in situ plasma separation, capillary flow and colorimetric reaction occurring concomitantly, without incurring additional device complexity or embodiment. The test reagents were dispensed in lyophilized form, and the resulting paper strips were found to be stable over three months stored in a normal freezer, rendering easy adaptability commensurate with the constrained supply chains in extreme resource-poor settings. Quantitative results could be arrived at via a completely-automated mobile-app-based image analytics interface developed using dynamic machine learning, obviating manual interpretation. The tests were demonstrated to be of high efficacy, even when executed by minimally trained frontline personnel having no special skill of drawing precise volume of blood, on deployment at under-resourced community centres having no in-built or accessible healthcare infrastructure. Clinical validation using 220 numbers of human blood samples in a double-blinded manner evidenced sensitivity and specificity of 98.11% and 96.7%, respectively, as compared to the results obtained from a laboratory-benchmarked biochemistry analyser, establishing its efficacy for public health and community disease management in resource-limited settings without any quality compromise of the test outcome.

The effect of hemolysis on quality control metrics for noninvasive prenatal testing

BACKGROUND

Noninvasive prenatal testing (NIPT) is the testing of blood samples from pregnant women to screen for fetal risk of chromosomal disorders. Even though in vitro hemolysis of blood specimens is common in clinical laboratories, its influence on NIPT has not been well investigated.

METHODS

Peripheral blood samples were collected from 205 pregnant women and categorized according to the concentration of free hemoglobin in the plasma. After performing NIPT using massively parallel sequencing, the quality control metrics were analyzed and compared with samples that did not undergo hemolysis or samples redrawn from the same women.

RESULTS

The specimens were divided into four groups based on the concentration of free hemoglobin: Group I (0-1 g/L, n = 53), Group II (1-2 g/L, n = 97), Group III (2-4 g/L, n = 30), and Group IV (> 4 g/L, n = 25). There was no significant difference in the quality control metrics of clinical samples with slight or moderate hemolysis (Group II and III). However, samples with severe hemolysis (Group IV) showed a significantly increased rate of duplicated reads (duplication rate) and fetal fraction, as well as decreased library concentration compared with samples without hemolysis. Moreover, the increase in fetal fraction caused by hemolysis was confirmed by redrawing blood samples in Group IV.

CONCLUSION

For NIPT using massively parallel sequencing, samples with slight or moderate hemolysis (≤ 4 g/L) are acceptable. However, careful consideration should be taken regarding the use of severely hemolyzed samples (> 4 g/L), since they might increase the risk of test failure.

Acid freezes uricolysis in addition to glycolysis: Utility of fluoride-EDTA-citrate tube in the measurement of uric acid for patients administered rasburicase

BACKGROUND

In samples from patients administered rasburicase, ex vivo uricolysis leads to spuriously low uric acid results. The manufacturer's recommendation of storing the sample in ice-water until analysis, however, does not fully arrest uricolysis. Since uricase activity is affected by pH and metal chelators, we assessed uricolysis inhibition in sodium fluoride-ethylenediaminetetraacetic acid (EDTA)-citrate sample tube (FC Mix tube, Greiner) used primarily for plasma glucose.

METHOD

A serum pool was spiked with rasburicase and uric acid measured at 15, 45, 90, 150, 240 and 1080 min in a lithium heparin tube in ice-water, plain tube at room temperature (RT), EDTA tube at RT, FC Mix tube in ice-water, FC Mix tube at RT and FC Mix tube at RT prepared by dissolving FC Mix in serum.

RESULTS

The rate of urate decay was lowest in the FC Mix tube independent of temperature, then lithium heparin tube in ice-water, then EDTA tube at RT and highest in the plain tube at RT. Uric acid concentrations in the prepared FC Mix tube at RT and heparin tube in ice-water were, respectively, 98.2% and 93.8% of control values at 90 min, 97.1% and 89.3% of control values at 4 h, and remained higher in the prepared FC Mix tube at all time points.

CONCLUSION

NaF-EDTA-citrate mixture largely arrested rasburicase mediated ex vivo uricolysis without the need for sample cooling. We propose that sample tubes containing NaF-EDTA-citrate be used for the measurement of uric acid in patients administered rasburicase.

Comparison of three different protocols for obtaining hemolysis

OBJECTIVES

Hemolysis is associated with erroneous or delayed results. Objectives of the study were to compare four different methods for obtaining hemolysis in vitro on three different analyzers.

METHODS

Hemolysis was prepared with addition of pure hemoglobin into serum pool, osmotic shock, aspiration through blood collection needle, freezing/thawing of whole blood. Biochemistry parameters were measured in duplicate at Architect c8000 (Abbott, Abbott Park, USA), Beckman Coulter AU680 (Beckman Coulter, Brea, USA) and Cobas 6000 c501 (Roche, Mannheim, Germany), according to manufacturers' declarations. Cut-off value was defined as the highest value of H index with corresponding bias lower than acceptance criteria.

RESULTS

We were not able to obtain results with freezing protocol. On all three platforms, lowest number of analytes were sensitive to hemolysis at H=0.5 using method of adding free hemoglobin. When osmotic shock was used, cut-off values for the most analytes were generally met at lower values. Hemolysis significantly interfered with measurement of potassium and lactate dehydrogenase (LD) at H=0.5 on all platforms. The most of the tested analytes had the lowest acceptable H index when aspiration method was used. At the low level of hemolysis (H=0.8) glucose, sodium, potassium, chloride, phosphate, and LD were affected on all analyzers, with some additional analytes depending on the manufacturer.

CONCLUSIONS

Hemolysis interference differs on different analyzers and according to protocol for obtaining hemolysis. Aspiration method was generally the most sensitive to hemolysis interference, while addition of free Hb was the most resistant.

Assessing the influence of true hemolysis occurring in patient samples on emergency clinical biochemistry tests results using the VITROS® 5600 Integrated system

Hemolysis is one of the most frequent causes of pre-analytical errors in the emergency department (ED), and it can lead to inaccurate blood results and often requires repeat testing. The purpose of the present study was to evaluate the effects of true hemolysis occurring in ED blood samples on routine clinical biochemistry tests using the VITROS^® 5600 Integrated system. A total of 92 pairs of blood samples were collected from 92 ED patients. Each pair of samples included one hemolyzed sample and one successful (non-hemolyzed) redraw from the same patient. A total of 21 common laboratory analytes and the hemolytic index (HI) were examined. The degree of hemolysis (slight, mild, moderate and heavy) was determined based on the HI. A clinically significant difference in one analyte was defined as a difference greater than its Clinical Laboratory Improvement Amendments of 1988 (CLIA'88) total allowable error (TAE) limits. The results demonstrated that the mean differences in 11 serum analytes (unconjugated bilirubin, Ca²⁺, equivalent CO₂, Cl^-, creatinine, glucose, Mg²⁺, phosphorus, Na⁺, urea nitrogen and uric acid) in hemolyzed and non-hemolyzed samples were within their CLIA'88 TAE limits, while the differences in the other 10 analytes [alanine aminotransferase (ALT), albumin (ALB), amylase (AMYL), aspartate aminotransferase (AST), total bilirubin (TBIL), creatine kinase (CK), CK-myocardial band isoenzyme (CK-MB), lactate dehydrogenase (LDH), K⁺ and total protein (TP)] in paired samples in at least one of the four groups were greater than their CLIA'88 TAE limits. These results suggest that hemolysis had a notable impact on ALT, ALB, AMYL, AST, TBIL, CK, CK-MB, LDH, K⁺ and TP levels. Furthermore, for ALT, AMYL, TBIL and TP, wet chemistry methods displayed superior anti-hemolytic ability compared with dry chemistry methods. Notably, a high concentration of AST was less affected by hemolysis.

Interferograms plotted with reference change value (RCV) may facilitate the management of hemolyzed samples

Background

The European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group for Preanalytical Phase (WG-PRE) have recommended an algorithm based on the reference change value (RCV) to evaluate hemolysis. We utilized this algorithm to analyze hemolysis-sensitive parameters.

Methods

Two tubes of blood were collected from each of the 10 participants, one of which was subjected to mechanical trauma while the other was centrifuged directly. Subsequently, the samples were diluted with the participant's hemolyzed sample to obtain the desired hemoglobin concentrations (0, 1, 2, 4, 6, 8, and 10 g/L). ALT, AST, K, LDH, T. Bil tests were performed using Beckman Coulter AU680 analyzer. The analytical and clinical cut-offs were based on the biological variation for the allowable imprecision and RCV. The algorithms could report the values directly below the analytical cut-off or those between the analytical and clinical cut-offs with comments. If the change was above the clinical cut-off, the test was rejected. The linear regression was used for interferograms, and the hemoglobin concentrations corresponding to cut-offs were calculated via the interferograms.

Results

The RCV was calculated as 29.6% for ALT. Therefore, ALT should be rejected in samples containing >5.9 g/L hemoglobin. The RCVs for AST, K, LDH, and T. Bil were calculated as 27.9%, 12.1%, 19.2%, and 61.2%, while the samples' hemoglobin concentrations for test rejection were 0.8, 1.6, 0.5, and 2.2 g/L, respectively.

Conclusions

Algorithms prepared with RCV could provide evidence-based results and objectively manage hemolyzed samples.

Plasma hemoglobin: A method comparison of six assays for hemoglobin and hemolysis index measurement

INTRODUCTION

Plasma hemoglobin (Hb) is measured for assessment of in vivo and in vitro hemolysis. The objective of the present investigation was to conduct a method comparison of five quantitative and one semi-quantitative Hb and H-index (hemolysis index) assays to evaluate their performance measuring plasma Hb in clinical specimens.

METHODS

One hundred and fourteen clinical specimens previously tested for plasma Hb using a laboratory-developed spectrophotometric assay were also tested for Hb using a HemoCue Plasma/Low Hb assay (azide methemoglobin), a laboratory-modified Pointe Scientific Hb assay (cyanmethemoglobin), tested for H-index measurements using a Roche cobas c501, an Abbott Architect c8000, and a semi-quantitative (binned) H-index measurement on a Beckman AU5800. The reference result was defined as the median Hb score (median of all Hb or H-index results).

RESULTS

The laboratory-developed spectrophotometric Hb assay and Roche H-index methods mostly closely matched the median Hb score across all data, as well as for lower range median Hb score results ≤2.0 g/L. Two-way frequency table analysis using an Hb (or H-index) cutoff of 0.5 g/L (or 0.5 H-index units) was then performed to compare methods to the median Hb score cutoff. The Beckman method had the highest accuracy at this cutoff, the Roche and Abbott methods had the highest positive predictive value (PPV), and the Beckman, HemoCue, and Pointe methods had the highest negative predictive value (NPV).

CONCLUSIONS

Plasma Hb and H-index results vary by method. Laboratories should evaluate the performance characteristics of their respective assays when considering adoption of spectrophotometric or chemical methods for plasma Hb assessment.

Effect of haemolysis on an enzymatic measurement of ethanol

Introduction

We investigated the interference of haemolysis on ethanol testing carried out with the Synchron assay kit using an AU680 autoanalyser (Beckman Coulter, Brea, USA).

Materials and methods

Two tubes of plasma samples were collected from 20 volunteers. Mechanical haemolysis was performed in one tube, and no other intervention was performed in the other tube. After centrifugation, haemolysed and non-haemolysed samples were diluted to obtain samples with the desired free haemoglobin (Hb) values (0, 1, 2, 5, 10 g/L). A portion of these samples was then separated, and ethanol was added to the separated sample to obtain a concentration of 86.8 mmol/L ethanol. After that, these samples were diluted with ethanol-free samples with the same Hb concentration to obtain samples containing 43.4, 21.7, and 10.9 mmol/L. Each group was divided into 20 equal parts, and an ethanol test was carried out. The coefficient of variation (CV), bias, and total error (TE) values were calculated.

Results

The TE values of haemolysis-free samples were approximately 2-5%, and the TE values of haemolysed samples were approximately 10-18%. The bias values of haemolysed samples ranged from nearly - 6.2 to - 15.7%.

Conclusions

Haemolysis led to negative interference in all samples. However, based on the 25% allowable total error value specified for ethanol in the Clinical Laboratory Improvement Amendments (CLIA 88) criteria, the TE values did not exceed 25%. Consequently, ethanol concentration can be measured in samples containing free Hb up to 10 g/L.

Using arterial blood as a substitute for venous blood in routine biochemistry parameter examinations in rabbits

Background

It has been widely accepted that there is a significant difference in peripheral blood oxygen between arteries and veins. Therefore, arterial blood has been collected for blood gas analysis, and venous blood, because it is convenient to collect, has been used for most laboratory examinations. However, venous blood is always difficult to collect in rabbits; in contrast, arterial blood is easier to obtain, and research on whether arterial blood can be used instead of venous blood for routine biochemical parameter examination is rare. Therefore, the present study was designed to explore whether arterial blood can be used as a substitute for venous blood for routine biochemistry parameter examination in rabbits.

Results

Three venous blood samples with gross hemolysis were excluded. Venous and arterial blood samples were obtained from forty-two rabbits. Arterial blood samples correlate well with venous blood in alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine transaminase (ALT), gamma-glutamyl transpeptidase (GGT), total protein (TP), globulin (GLB), serum total cholesterol (TC), serum triglyceride (TG), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), urea (Ur) and creatinine (Cr) levels by Deming regression analysis with slopes ranging from 0.893 to 1.176 and intercepts ranging from − 4.886 to 5.835. Bland-Altman analysis showed that the two sample parameters had 93%-98% of the points within the 95% consistency limits. There were significant differences between venous blood and arterial blood in ALP, TP, TC, TG, HDL, LDL and Cr, while AST, ALT, GGT, GLB and Ur showed no significant differences.

Conclusions

Arterial blood can be a substitute for venous blood in routine biochemistry parameter examinations in rabbits, especially in situations where venous blood is difficult to collect.

Handling of hemolyzed serum samples in clinical chemistry laboratories: the Nordic hemolysis project

Background Some clinical chemistry measurement methods are vulnerable to interference if hemolyzed serum samples are used. The aims of this study were: (1) to obtain updated information about how hemolysis affects clinical chemistry test results on different instrument platforms used in Nordic laboratories, and (2) to obtain data on how test results from hemolyzed samples are reported in Nordic laboratories. Methods Four identical samples containing different degrees of hemolysis were prepared and distributed to 145 laboratories in the Nordic countries. The laboratories were asked to measure the concentration of cell-free hemoglobin (Hb), together with 15 clinical chemistry analytes. In addition, the laboratories completed a questionnaire about how hemolyzed samples are handled and reported. Results Automated detection of hemolysis in all routine patient samples was used by 63% of laboratories, and 88% had written procedures on how to handle hemolyzed samples. The different instrument platforms measured comparable mean Hb concentrations in the four samples. For most analytes, hemolysis caused a homogenous degree of interference regardless of the instrument platform used, except for alkaline phosphatase (ALP), bilirubin (total) and creatine kinase (CK). The recommended cut-off points for rejection of a result varied substantially between the manufacturers. The laboratories differed in how they reported test results, even when they used the same type of instrument. Conclusions Most of the analytes were homogeneously affected by hemolysis, regardless of the instrument used. There is large variation, however, between the laboratories on how they report test results from hemolyzed samples, even when they use the same type of instrument.

A Reference chart for clinical biochemical tests of hemolyzed serum samples

Background

Although the effect of hemolysis has been extensively evaluated on clinical biochemical tests, a practical guidance for laboratory staff to rapidly determine whether a hemolyzed blood sample is acceptable and how to interpret the results is lacking. Here, we introduce a chart as a convenient reference for dealing with such samples.

Methods

Serum samples with 0.1%, 0.3%, 1%, 3%, and 10% hemolysis were prepared from sonicated endogenous red blood cells and received 35 wet and 22 dry clinical biochemical tests, respectively. The contributing part in the biochemical test result at each hemolysis condition was derived by subtracting the original test result of this sample with no hemolysis. The net results were used for analyses and preparation of the reference chart.

Results

The reference chart displayed the analytically calculated hemolysis interference and related statistical analyses. The chart also provided the color appearance of serum samples at each hemolysis condition for clinical staffs to determine whether a hemolyzed sample could be accepted.

Conclusion

In clinical laboratories, preparation of such a reference chart is extremely useful in dealing with hemolyzed blood samples for clinical biochemical tests.

The Estimation of Postmortem Serum Urea via the Ultrafiltration of Hemolyzed Blood

Postmortem serum urea has been demonstrated as an objective indicator for the forensic diagnosis of cause of death. However, samples used in postmortem biochemical analysis are always affected by hemolysis. To investigate whether hemolysis affects the biochemical analysis of urea and to explore the feasibility of using ultrafiltration to process hemolyzed blood samples, three different levels of hemolyzed blood samples were used to assess the influence of hemolysis on postmortem biochemical analysis of urea, and two ultrafiltration methods were used to process the hemolyzed blood samples. Bias% was used to assess the interference of hemolysis. Our results showed that heavy hemolysis had a significant influence on the biochemical analysis of urea. Both ultrafiltration methods in the present study could significantly reduce the interference of hemolysis, with the |bias%| of methods A and B decreasing from 69.74% ± 99.14% to 12.18% ± 7.23% and 10.77% ± 8.09%, respectively, compared to the original serum. After regression correction, there was no significant difference between the urea concentration in the ultrafiltrates of the two ultrafiltration methods and that in the original serum, which suggested that the postmortem serum urea concentration could be estimated by the corrected urea concentration in the ultrafiltrate. The current study also provided possible pretreatment methods for postmortem biochemical analysis of other biomarkers in hemolyzed blood samples of forensic practice.

A simple and rapid method for blood plasma separation driven by capillary force with an application in protein detection

Blood plasma separation is a vital sample pre-treatment procedure for microfluidic devices in blood diagnostics, and it requires reliability and speediness. In this work, we propose a novel and simple method for microvolume blood plasma separation driven by capillary force. Flat-shaped filter membranes combined with hydrophilic narrow capillaries are introduced into devices, in order to reduce the residual volumes of blood plasma. An interference fit is used to ensure no leakage of blood or cells. There is desired trapping efficiency of blood cells in the devices. The method provides high efficiency with a plasma extraction yield of 71.7% within 6 min, using 60 μL of undiluted whole human blood with 45% haematocrit. The influence from structural parameters on the separation kinetics and the dependence of the haematocrit levels on the separation efficiency are also investigated. The total protein detection shows considerable protein recovery of 82.3% in the extracted plasma. Thus, the plasma separation unit with a very simple structure is suitable for integrating into microfluidic devices, presenting promising prospects for clinical diagnostics as well as for point-of-care testing applications.

Determination of hemolysis cut-offs for biochemical and immunochemical analytes according to their value

Background

All general biochemistry instruments allow the measure of hemolysis index (HI), and suppliers provide an acceptable HI for each assay without consideration of the analyte value or its clinical application. Our first objective was to measure the impact of hemolysis degree on plasma biochemical and immunochemical analytes to determine the maximum allowable HI for each of them using four calculation methods as significant bias in comparison to manufacturer’s data. The second objective was to assess whether the maximum allowable HI varied according to the analyte values.

Methods

Twenty analytes were measured in hemolyzate-treated plasma to determine the HI leading to a significant change compared to baseline value. Analytes were assessed at one (3 analytes), two (5 analytes) and three (12 analytes) values according to their sensitivity to hemolysis and their clinical impact. We used four calculation methods as significant limit from baseline value: the total change limit (TCL), the 10% change (10%Δ), the analytical change limit and the reference change value.

Results

Allowable HI was significantly different according to the threshold chosen for most analytes and was also dependent on the analyte value for alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase, iron, haptoglobin and high sensitivity troponin T. No hemolysis interference was observed for albumin, creatinine, C-reactive protein, and procalcitonin even at an HI value of 11 g/L.

Conclusions

This study highlights that TCL is the most appropriate calculation method to determine allowable HI in practice for biochemical and immunochemical parameters using Cobas 8000© from Roche Diagnostics. In addition, different allowable HI were found according to analyte value leading to optimization of resampling to save time in patient care.

Individualized Correction of the Interference of Hemolysis on Glycated Albumin Determined by the Ketamine Oxidase Method

OBJECTIVE

To investigate the effect of hemolysis on glycated albumin (GA) levels, as determined by the ketamine oxidase method.

METHODS

GA levels and the hemolysis index were determined in nonhemolyzed serum and hemolyzed serum from corresponding patients. We developed an equation to correct the interference of hemolysis on GA, using multiple regression analysis.

RESULTS

The degree of hemolysis was negatively correlated with GA levels (R2 = 0.9500). A correction equation for GA (corrected GA = 2.703 × OD of hemolysis + 1.044 × measured GA -0.906) can revert GA concentrations of hemolyzed specimens to values that were not significantly different from the GA concentration of corresponding nonhemolyzed specimens. The bias of GA concentrations before and after correction was statistically significantly different (P <.01).

CONCLUSIONS

Our results indicate that the level of GA measured through the ketamine oxidase method is negatively affected by hemolysis. The individualized correction of GA results provides increased accuracy in hemolyzed specimens.