Dynamics of reactive oxygen species generation in the presence of copper(II)-histidine complex and cysteine.

Histidine-copper(II) complex (Cu-His2) is a form of bound copper necessary for cellular copper uptake. Due to the high affinity of histidine to copper(II) ions, the binding of copper(II) by histidine is considered a substantial part of plasma antioxidative defense. Also cysteine plays a role in the antioxidative system. However, we show here that in the presence of oxygen the histidine-copper(II) complex plus cysteine produces reactive oxygen species (ROS). Cysteine concentration was assayed using a thiol specific silver-mercury electrode. Hydrogen peroxide was assayed amperometrically using platinum electrode. ROS formation was followed by chemiluminescence of luminol-fluoresceine-enhanced system. Addition of cysteine to Cu-His2 solution at pH 7.4 in the presence of atmospheric oxygen initiates the synthesis of H2O2 and generation of ROS, which manifests as a burst of chemiluminescence. The reaction has two stages; in the first stage, cysteine is utilized for the synthesis of an unstable intermediary product which becomes a substrate for ROS formation. Anaerobic conditions inhibit ROS formation. Increased cysteine concentration enhances the lag phase of the oxidative burst without influencing the amount of ROS. The synthesis of ROS (measured by chemiluminescence) is proportional to the concentration of Cu-His2 employed. ROS production can be repetitively initiated by further additions of cysteine to the reaction medium. The study suggests that Cu-His2 catalyzes cysteine-dependent reduction of oxygen to superoxide employing an intermediary cysteine-copper(I) complex and enabling Fenton reaction with copper and hydrogen peroxide produced as a secondary product. In effect, Cu-His2 with cysteine may be a source of ROS in biological media.

Effect of hemodialysis on acid leukocyte-type ribonuclease, alkaline ribonuclease and polymorphonuclear elastase serum levels in patients with end-stage renal disease.

BACKGROUND: Low-molecular-weight proteins (LMWPs) are substances of molecular weights 10-35 kDa, which accumulate in plasma of patients with end-stage renal disease (ESRD) due to the abolishment of plasma renal filtration. LMWPs are considered as a separate group of uremic toxins. AIM: The influence of hemodialysis (HD) on the release of some LMWPs from leukocytes was assessed by comparing levels of serum pancreatic-type alkaline RNase and leukocyte-type acid RNase as well as polymorphonuclear (PMN) elastase. METHODS: The mentioned proteins were assayed in 58 ESRD patients on HD prior and after the dialysis session and compared with the results obtained from 36 healthy subjects. The levels of elastase and acid and alkaline RNase were correlated with HD parameters, residual diuresis, predialysis concentrations of serum creatinine, urea and albumin as well as pre- and postdialysis granulocyte count. RESULTS: Changes in PMN elastase produced by the dialysis session positively correlate with changes in acid RNase levels (r = 0.3650; p = 0.0061), while there is no such correlation for alkaline RNase. There is a negative correlation between pre- and postdialysis differences in levels of acid and alkaline RNases (r = -0.3542; p = 0.008), indicating that HD induces liberation of a factor suppressing alkaline RNase. Levels of acid and alkaline RNase negatively correlate with residual diuresis, indicating its significance in control of LMWP accumulation (r = -0.3970; p = 0.0025; r = -0.2596; p = 0.0533, respectively). CONCLUSIONS: Dialysis treatment causes an increase in both acid leukocyte-type and alkaline pancreatic-type RNase activity in plasma. Dialysis-related increases in acid RNase activity correlate with the respective changes in PMN elastase, which suggests that leukocyte activation during dialysis contributes to an increase in plasma LMWPs.

Comparison of high-sensitivity C-reactive protein serum assay results obtained using Dade-Behring BNII nephelometer and Ortho Vitros FS 5.1 clinical analyzer in respect of CRP-related risk assessment of chronic metabolic diseases.

BACKGROUND: Serum concentration of high sensitive C-reactive protein (hsCRP) can predict the risk of chronic metabolic and cardiovascular diseases but it is unclear whether turbidimetric high sensitive assays of CRP are adequate. METHODS: Concentrations of serum CRP in 126 samples of serum were measured with high-sensitivity methods using nephelometry (BN II Nephelometer) and turbidimetry (Ortho Vitros FS 5.1). RESULTS: For CRP concentrations measured by nephelometry and turbidimetry intra-assay CVs were 3.2 and 0.9% at mean CRP concentrations of 1.4 and 2.1 mg/l, inter-assay CVs for commercial controls were 3.1% and 3.6% at mean concentrations of 1.3 and 1.7 mg/l, and mean biases were 7.62% and 2.26%, respectively. Measurements were strongly, linearly correlated (r = 0.99; CRP vitros = 0.03 +1.03 CRP (BN II)). When disease risk was assessed by nephelometry and turbidimetry, results were similar. If the risk of disease was classified as moderate (1.0 < CRP < or = 3.0 mg/l) or high (CRP > 3.0 mg/l), the frequency of misclassified cases was only 2.3 and 2.1%, respectively. The classification agreement weighted kappa coefficient was 0.94 (95% C.I.: 0.89-0.98). CONCLUSIONS: turbidimetric high sensitive CRP assays can properly classify CRP-related prediction of chronic metabolic diseases with special consideration on cardiovascular risk.

Assessment of the prognostic value of certain acute-phase proteins and procalcitonin in the prognosis of acute pancreatitis.

OBJECTIVES: Of patients with acute pancreatitis (AP), 20% develop severe attacks that need early and intensive therapy. Yet, to administer such treatment, it is important to classify early on the patients with mild and severe pancreatitis. The aim of this study was to evaluate the role of serum amyloid A, C-reactive protein, procalcitonin, and routinely measured parameters in the early prediction of the course of AP. METHODS: A total of 40 consecutive patients with AP confirmed by computed tomography were prospectively enrolled in the study-29 were graded as mild and 11 were graded as severe. Blood samples were obtained on admission and 24 hours thereafter. RESULTS: Procalcitonin concentration in both measurements was significantly higher in patients with severe pancreatitis, and the cutoff level was estimated at 0.5 ng/mL. Although serum amyloid A and C-reactive protein levels rose significantly during the period of observation, these were not differentiated between both groups. Among the routinely measured parameters, a prognostic value was found for total calcium concentration, lactic dehydrogenase activity, and glucose concentration. CONCLUSIONS: The best efficiency in the early prediction of severe AP would be achieved with the measurement of procalcitonin, total calcium level, and lactic acid dehydrogenase activity immediately after admission to the ward.

Functional C1-inhibitor diagnostics in hereditary angioedema: assay evaluation and recommendations.

Hereditary angioedema (HAE) is an autosomal dominant disease characterized by recurrent episodes of potentially life-threatening angioedema. The most widespread underlying genetic deficiency is a heterozygous deficiency of the serine protease inhibitor C1 esterase inhibitor (C1-Inh). In addition to low C4 levels, the most important laboratory parameter for correct diagnosis of HAE or angioedema due to acquired C1-Inh deficiency is reduced C1-Inh function (fC1-Inh). No direct recommendations about the assays for fC1-Inh or sample handling conditions are available, although this would prove especially useful when a laboratory first starts to offer assays on fC1-Inh for HAE diagnosis. In the present study we evaluated the performance of fC1-Inh assays in the 15 different laboratories that are specialised in HAE diagnostics and assessed inter-laboratory variation with each laboratory using their own assays and standards. A double-blind survey was conducted using plasma/serum samples from healthy donors and HAE patients and the uniformity of HAE diagnosis was evaluated. It can be concluded that the diagnosis of fC1-Inh deficiency was made correctly in most cases in this survey. We can recommend the chromogenic assay for the determination of fC1-Inh, while the complex ELISA needs further investigation.

Analytical evaluation of the Optium Xido blood glucose meter.

BACKGROUND: The main prevention of chronic diabetic complications is maintaining near normoglycemia. In this study, evaluation of analytical performance of the Optium Xido blood glucose meter designed for patients' self-monitoring of glycemia was carried out. METHODS: Glucose concentrations were measured in 118 EDTA blood samples using the Xido glucose meter and the GOD/PAP method on a Modular P clinical analyzer. The results obtained were used for the assessment of accuracy, precision and linearity. Performance of the Xido glucose meter was also assessed using four different reagent strip lots, and the between-lot variation was calculated. RESULTS: The within-run imprecision coefficient of variation (CV) amounted to 4.2%. Good response linearity was found in glucose concentrations of 31-444 mg/dL (1.7-24.7 mmol/L). In the concentration range studied, the glucose meter error was 5.14% and the linear regression equation was y=0.91x+6.2, (r=0.984). The Passing-Bablok agreement test indicated good concordance of results. However, for glucose concentrations<100 mg/dL (5.6 mmol/L) (n=69) the error was 6.82% with regression equation y=0.86x+5.9 (r=0.757). Between-lot differences amounted to 0.7%-18.2%. CONCLUSIONS: The Xido glucose meter has good precision and accuracy when compared to the laboratory method and meets the quality recommendations of the National Committee of Clinical Laboratory Standards (NCCLS, currently the Clinical Laboratory Standards Institute), the National Academy of Clinical Biochemistry (NACB) and the International Organization for Standardization (ISO). However, between-lot variability may result in differences between day-to-day results when the device is continuously used. Therefore, the validation of new lots of reagent strips with a laboratory method is recommended.

IFCC guideline for sampling, measuring and reporting ionized magnesium in plasma.

Analyzers with ion-selective electrodes (ISEs) for ionized magnesium (iMg) should yield comparable and unbiased results for iMg. This IFCC guideline on sampling, measuring and reporting iMg in plasma provides a prerequisite to achieve this goal [in this document, "plasma" refers to circulating plasma and the forms in which it is sampled, namely the plasma phase of anticoagulated whole blood (or "blood"), plasma separated from blood cells, or serum]. The guideline recommends measuring and reporting ionized magnesium as a substance concentration relative to the substance concentration of magnesium in primary aqueous calibrants with magnesium, sodium, and calcium chloride of physiological ionic strength. The recommended name is "the concentration of ionized magnesium in plasma". Based on this guideline, results will be approximately 3% higher than the true substance concentration and 4% lower than the true molality in plasma. Calcium ions interfere with all current magnesium ion-selective electrodes (Mg-ISEs), and thus it is necessary to determine both ions simultaneously in each sample and correct the result for Ca2+ interference. Binding of Mg in plasma is pH-dependent. Therefore, pH should be measured simultaneously with iMg to allow adjustment of the result to pH 7.4. The concentration of iMg in plasma may be physiologically and clinically more relevant than the concentration of total magnesium. Furthermore, blood-gas analyzers or instruments for point-of-care testing are able to measure plasma iMg using whole blood (with intact blood cells) as the sample, minimizing turn-around time compared to serum and plasma, which require removal of blood cells.

Effect of moderate hypercholesterolemia on recognition of hypernatremia using indirect measurements of serum sodium and potassium concentrations.

BACKGROUND: Na+ and K+ concentration measurements by ion-selective electrodes and flame photometry are affected by lipids influencing plasma water content. METHODS: In 166 sera with total cholesterol ranging from 1.19 to 23.3 mmol/L, and triglycerides ranging from 0.34 to 56.3 mmol/L, Na+ and K+ concentrations were assayed using flame photometry and direct ion-selective electrodes of the Vitros 950 analyzer. Linear regression analysis was used to examine inter-method difference as lipid content variable. RESULTS: In hypercholesterolemia and hypertriglyceridemia flame photometry yielded Na+ concentrations lower by 1.85% and 2.15% than ion-selective electrode measurements (p < 0.05). Na+ concentration inter-method difference correlated with total cholesterol and triglycerides. In bivariate analysis, inter-method difference significantly depended on total cholesterol (r2 = 0.09), whereas the impact of triglycerides was weak. In trivariate analysis, total cholesterol had the highest impact (r2 = 0.12), followed by Na+ concentration (r2 = 0.04), while the impact of triglycerides was insignificant. Recognition of hypernatremia significantly depended on total cholesterol (chi2 p = 0.0017); 27% of samples with hyperlipidemia (total cholesterol > 5.2 mmol/L, triglycerides > 2.5 mmol/L) classified as normonatremia by flame photometry presented hypernatremia by direct ion-selective electrode. CONCLUSIONS: The lipid status of patients influences recognition of hypernatremia if assays are based on total plasma volume. No effect of lipids was observed on the recognition of hyperkalemia.

[Diagnostic value of serum amyloid A protein (SAA) determination]. / Wartosc diagnostyczna oznaczen osoczowego bialka amyloidowego A (SAA).

Although serum amyloid A (SAA) was discovered almost 25 years ago, its biological role is still unknown. Similarly to C-reactive protein, SAA belongs to acute reaction proteins, synthesised in the liver after stimulation by proinflammatory cytokines like: TNFalpha, IL-1beta and IL-6. SAA level in acute inflammatory process of bacterial, mycotical, autoimmunological, oncological or extensive tissue damage is from 100 to 1000 mg/l. Additional SAA examination in patients with oncological disorders is accepted as a valuable survival index.

An example of a bootstrap technique application for judging a variability of method performance estimates and its consequences for quality control planning.

BACKGROUND: Flexible fitting of quality control procedures to method performance is an inseparable element of a cost-effective quality management strategy. However, opinions on method performance, based on a restricted number of quality control results used to calculate bias and imprecision, can vary due to the random nature of the data-gathering process. METHODS: We present an example of the bootstrap technique application in evaluating method performance estimates. RESULTS: Our analysis reveals substantial variability in method performance assessment results that should not be omitted. We suggest that the best way of using information concerning method performance is to consider the information in a probabilistic manner. Method performance is a feature presented with an element of probability. The effectiveness of a quality control procedure should be assessed with regard to this probability. CONCLUSIONS: Presented example of a bootstrap technique application increases our awareness of the uncertainty that accompanies method performance judgment and quality control planning.

Potentiometric determination of cysteine with thiol sensitive silver-mercury electrode.

A potentiometric procedure for cysteine thiol group concentration monitoring in media generating free radicals was developed using a thiol specific silver-mercury electrode. Electrolytic deposition of mercury on a silver wire and treatment with 20 mM cysteine in 0.5 M NaOH were used to produce the electrode. A silver-chloride electrode in saturated KCl was the reference. A glass capillary with 1 M KNO3 in 1% agarose gel was the liquid junction. The electrode responded to cysteine concentration in the range from 0.01 to 20 mM yielding a perfect linear relationship for the dependence of log [cysteine] versus electrode potential [mV], with b0 (constant) = -373.43 [mV], b1 (slope) = -53.82 and correlation coefficient r2 = 0.97. The electrode potential change per decade of cysteine concentration was 57 mV. The minimal measurable signal response was at a cysteine concentration of 0.01 mM. The signal CV amounted to 4-6% for cysteine concentrations of 0.01 to 0.05 mM and to less than 1% for cysteine concentrations of 0.5 to 20 mM. The response time ranged from about 100 s for cysteine concentrations of 0.01 to 0.1 mM to 30 s at higher cysteine concentrations. The standard curve reproducibility was the best at cysteine concentrations from 0.1 to 20 mM. In a reaction medium containing cysteine and copper(II)-histidine complex ([His-Cu]2+) solution in 55 mM phosphate buffer pH 7.4 the electrode adequately responded to changes in cysteine concentration. Beside cysteine, the silver-mercury electrode responded also to thiol groups of homocysteine and glutathione, however, the Nernst equation slope was about half of that for cysteine.

Quality control of self-monitoring of blood glucose: why and how?

The control of analytical quality of self-monitoring of blood glucose (SMBG) is recommended as a routine procedure in diabetes management. This control procedure should be easily accessible to patients, convenient, not time-consuming, and provide a reliable assessment of glucose meter performance. Optimally it should be located in the diabetes outpatient clinic. Presently there are two approaches to carrying out SMBG quality control. The first is based on the comparison of results obtained by a controlled glucose meter and use of the laboratory method or point-of-care testing device as a surrogate reference analyzer. The second one is a traditionally organized external quality assessment scheme with use of a dedicated control material, which is distributed to all participants. The recommended allowable meter error in SMBG can be realistically set at 10%.

Approved IFCC recommendation on reporting results for blood glucose: International Federation of Clinical Chemistry and Laboratory Medicine Scientific Division, Working Group on Selective Electrodes and Point-of-Care Testing (IFCC-SD-WG-SEPOCT).

In current clinical practice, plasma and blood glucose are used interchangeably with a consequent risk of clinical misinterpretation. In human blood, glucose is distributed, like water, between erythrocytes and plasma. The molality of glucose (amount of glucose per unit water mass) is the same throughout the sample, but the concentration is higher in plasma, because the concentration of water and therefore glucose is higher in plasma than in erythrocytes. Different devices for the measurement of glucose may detect and report fundamentally different quantities. Different water concentrations in the calibrator, plasma, and erythrocyte fluid can explain some of the differences. Results for glucose measurements depend on the sample type and on whether the method requires sample dilution or uses biosensors in undiluted samples. If the results are mixed up or used indiscriminately, the differences may exceed the maximum allowable error for glucose determinations for diagnosing and monitoring diabetes mellitus, thus complicating patient treatment. The goal of the International Federation of Clinical Chemistry and Laboratory Medicine, Scientific Division, Working Group on Selective Electrodes and Point of Care Testing (IFCC-SD-WG-SEPOCT) is to reach a global consensus on reporting results. The document recommends reporting the concentration of glucose in plasma (in the unit mmol/L), irrespective of sample type or measurement technique. A constant factor of 1.11 is used to convert concentration in whole blood to the equivalent concentration in plasma. The conversion will provide harmonized results, facilitating the classification and care of patients and leading to fewer therapeutic misjudgments.

Role of growth hormone and insulin-like growth factor-1 in the protective effect of ghrelin in ischemia/reperfusion-induced acute pancreatitis.

Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor, has been shown to exhibit gastroprotective properties. The aim of present study was to determine whether ghrelin administration protects the pancreas against ischemia/reperfusion-induced pancreatitis and, if so, what is the role of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in this effect. In sham-operated or hypophysectomized rats, acute pancreatitis was induced by pancreatic ischemia followed by reperfusion. Ghrelin (4, 8 or 16 nmol/kg/dose) or IGF-1 (20 nmol/kg/dose) were administered intraperitoneally twice before and during induction of acute pancreatitis. In pituitary-intact rats, treatment with ghrelin attenuated the development of ischemia/reperfusion-induced pancreatitis and this effect was associated with partial reversion of the pancreatitis-evoked decrease in serum concentration of GH and IGF-1. Hypophysectomy eliminated GH from the serum, reduced serum IGF-1 concentration by 90% and increased in the severity of ischemia/reperfusion-induced pancreatitis. Administration of ghrelin was without any beneficial effect in this group of rats. In contrast, administration of IGF-1 in hypophysectomized rats reduced the severity of ischemia/reperfusion-induced pancreatitis in hypophysectomized rats. We conclude that administration of ghrelin inhibits the development of ischemia/reperfusion-induced pancreatitis and this effect is mediated by its influence on the release of GH and IGF-1.

Recommendation for measuring and reporting chloride by ISEs in undiluted serum, plasma or blood.

The proposed recommendation for measuring and reporting chloride in undiluted plasma or blood by ion-selective electrodes (ISEs) will provide results that are identical to chloride concentrations measured by coulometry for standardized normal plasma or blood samples. It is applicable to all current ISEs dedicated to chloride measurement in undiluted samples that meet the requirements. However, in samples with reduced water concentration, results by coulometry are lower than by ion-selective electrode due to volume displacement. The quantity measured by this standardized ISE procedure is called the ionized chloride concentration. It may be clinically more relevant than the chloride concentration as determined by coulometry, photometry or by ISE after dilution of the sample.

[Analysis of selected inflammatory markers in patients with stable renal graft (RTx) 36 months after transplantation]. / Ocena wybranych parametrów zapalnych u pacjentów ze stabilnym przeszczepem nerki po 36 miesiacach od transplantacji.

Chronic inflammation is an inherent feature of chronic renal failure. Successful renal transplantation (RTx) is the only known renal replacement therapy sufficient to reverse most of the metabolic disturbances of chronic uremia, although still some of these abnormalities may be present or even new problems may occur (mostly as the side effects of immunosuppressive drugs). The aim of this study was to evaluate the level of inflammation in 20 patients (9 F, 11 M, aged mean 44.0 +/- 11.8 years) with well-preserved renal function 36 months after kidney transplantation, using serum levels of selected cytokines (IL-6, IL-18, TNFalpha and soluble receptor for TNF - sTNFRII), acute phase proteins (CRP, fetuin A) and hepatocyte growth factor (HGF). Procalcitonin was also assessed as the sensitive indicator of active infection. Obtained results were compared with the control group of healthy subjects in a respective age. Serum levels of IL-6, TNF-R and IL-18 were significantly higher, and HGF and fetuin A--significantly lower in patients vs. controls (p < 0.05 for all differences). Significant negative correlations were noted between glomerular filtration rate (GFR) and serum TNF, sTNFRII and IL-18 in RTx patients, whereas strong positive relationship between GFR and fetuin A was observed. Serum creatinine correlated with IL-6, IL-18, TNFalpha, sTNFRII and hsCRP levels and serum urea-with TNFalpha, sTNFRII, IL-6 and IL-18. Significant negative associations were also noticed between serum fetuin A and most of the tested inflammatory markers: sTNFRII (r = -0.77; p = 0.0005), IL-6 (r = -0.63; p = 0.009), hsCRP (r = -0.62; p = 0.009) and IL-18 (r = -0.60; p = 0.01). Obtained results permit us to conclude that the increased activity of inflammation can still be noticed in RTx patients 36 months after successful engraftment. This process is inversely associated with the level of kidney function. The role of fetuin A as the 'negative' acute phase protein was also demonstrated in this group of patients.

[Usefulness of interleukin 18 determination in clinical diagnostics]. / Przydatnosc oznaczen interleukiny 18 w diagnostyce klinicznej.

Interleukin-18 (IL-18) is a proinflammatory pleiotropic cytokine playing a major role in the inflammatory cascade. It was written up for the first time in 1995 as a factor inducing interferon gamma in Kupffer cells, macrophages as well as T and B cells. Authors are presenting actual publications concerning usefulness in interleukin 18 determination in clinical diagnostics.

Ischemic preconditioning inhibits development of edematous cerulein-induced pancreatitis: involvement of cyclooxygenases and heat shock protein 70.

AIM: To determine whether ischemic preconditioning (IP) affects the development of edematous cerulein-induced pancreatitis and to assess the role of cyclooxygenase-1 (COX-1), COX-2, and heat shock protein 70 (HSP 70) in this process. METHODS: In male Wistar rats, IP was performed by clamping of celiac artery (twice for 5 min at 5-min intervals). Thirty minutes after IP or sham operation, acute pancreatitis was induced by cerulein. Activity of COX-1 or COX-2 was inhibited by resveratrol or rofecoxib, respectively (10 mg/kg). RESULTS: IP significantly reduced pancreatic damage in cerulein-induced pancreatitis as demonstrated by the improvement of pancreas histology, reduction in serum lipase and poly-C ribonuclease activity, and serum concentration of pro-inflammatory interleukin (IL)-1beta. Also, IP attenuated the pancreatitis-evoked fall in pancreatic blood flow and pancreatic DNA synthesis. Serum level of anti-inflammatory IL-10 was not affected by IP. Cerulein-induced pancreatitis and IP increased the content of HSP 70 in the pancreas. Maximal increase in HSP 70 was observed when IP was combined with cerulein-induced pancreatitis. Inhibition of COXs, especially COX-2, reduced the protective effect of IP in edematous pancreatitis. CONCLUSION: Our results indicate that IP reduces pancreatic damage in cerulein-induced pancreatitis and this effect, at least in part, depends on the activity of COXs and pancreatic production of HSP 70.

Approved IFCC recommendation on reporting results for blood glucose (abbreviated).

In current clinical practice, plasma and blood glucose are used interchangeably with a consequent risk of clinical misinterpretation. In human blood, glucose, like water, is distributed between erythrocytes and plasma. The molality of glucose (amount of glucose per unit of water mass) is the same throughout the sample, but the concentration is higher in plasma because the concentration of water and, therefore, glucose is higher in plasma than in erythrocytes. Different devices for the measurement of glucose may detect and report fundamentally different quantities. Different water concentrations in calibrators, plasma, and erythrocyte fluid can explain some of the differences. Results of glucose measurements depend on sample type and on whether methods require sample dilution or use biosensors in undiluted samples. If the results are mixed up or used indiscriminately, the differences may exceed the maximum allowable error of glucose determinations for diagnosing and monitoring diabetes mellitus, and complicate the treatment. The goal of the IFCC Scientific Division Working Group on Selective Electrodes and Point of Care Testing (IFCC-SD, WG-SEPOCT) is to reach a global consensus on reporting results. The document recommends reporting the concentration of glucose in plasma (with the unit mmol/L), irrespective of sample type or measurement technique. A constant factor of 1.11 is used to convert concentration in whole blood to the equivalent concentration in the pertinent plasma. The conversion will provide harmonized results, facilitating the classification and care of patients and leading to fewer therapeutic misjudgments.

Quality control of SMBG in clinical practice.

We present results of quality control of self-monitored blood glucose (SMBG) performed in diabetes outpatient clinic. The tests included: inspection of glucose meter, blood glucose self-measurement by a patient, glucose measurement by point-of-care analyzer used in a clinic and with the laboratory method. In the study 158 glucose meters were controlled and compared with HemoCue glucose analyzer used in the clinic as the reference. 122 glucose meters readings were also compared with the reference laboratory method. Tested glucose meters included: Accutrend {18}, Glucotrend {59}, Precision QiD {39}, One Touch {26} and Glucocard II {16}. Reference glucose assays were performed using glucose oxidase method on Hitachi 911 analyzer. Glucose concentrations measured by the controlled glucose meters ranged from 36 to 425 mg/dL. The analytical bias of the glucose meters amounted from 2.48% to 8.27%. Correlation coefficient between results obtained by the tested glucose meters and HemoCue analyzer ranged from 0.957 to 0.980 and between glucose meters and laboratory method from 0.955 to 0.985. Passing-Bablok agreement test and Deming regression analysis indicated good concordance of results between all the tested glucose meters and HemoCue analyzer, whereas good agreement with the laboratory method was found for Accutrend, Glucotrend, Precision QiD and One Touch glucose meters. In conclusion, good analytical performance of the employed glucose meters and a bias less than 10% from the reference values were found. Results of this study show the possibility for routine, convenient for the patient quality control of SMBG in an outpatient clinic.