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Objective: To investigate the association of immune response with vaccination adverse effects at peak anti–receptor-binding domain spike subunit 1 (anti-RBDS1) IgG after full vaccination with Comirnaty, Spikevax, or Vaxzevria. Methods: Anti-RBDS1 IgG concentrations after vaccination were determined in healthy adults vaccinated with the Comirnaty, Spikevax, and Vaxzevria vaccines. The association of reactogenicity and peak antibody response after vaccination was tested. Results: Anti-RBDS1 IgG values were significantly higher in the Comirnaty and Spikevax group, compared with the Vaxzevria group (P < .001). Fever and muscle pain were found to be significant independent predictors of peak anti-RBDS1 IgG in the Comirnaty and Spikevax groups (P = .03 and P = .02, respectively). The multivariate model, adjusted for covariates, showed that no association between reactogenicity and peak antibody concentrations was found in the Comirnaty, Spikevax, and Vaxzevria groups. Conclusions: No association between reactogenicity and peak anti-RBDS1 IgG after vaccination with the Comirnaty, Spikevax, and Vaxzevria vaccine was found.

Antagonisti faktora nekroze tumora α (engl. Tumor Necrosis Factor, TNF-α) učinkoviti su u liječenju autoimunih reumatoidnih i upalnih bolesti crijeva, ali se čak u 30 % bolesnika ne postiže remisija bolesti. Cilj istraživanja bio je ispitati postoji li razlika u kliničkom i biokemijskom odgovoru na terapiju anti-TNF-α protutijelima ovisno o polimorfizmima gena TNF-α na položajima -238 G/A (rs361525) i - 308 G/A (rs1800629). U istraživanje je bilo uključeno 112 bolesnika od čega 66 s upalnim bolestima crijeva te 46 bolesnika s autoimunim reumatoidnim bolestima. Na terapiji infliksimabom (IFX) bilo je ukupno je 73 bolesnika, a 39 na terapiji adalimumabom (ADM). Bolesnici su praćeni 6 do 12 mjeseci od početka biološke terapije. Svim je bolesnicima određena koncentracija C reaktivnog proteina (CRP), lijekova IFX i ADM i protutijela na te lijekove kao i genotip polimorfizama rs361525 i rs1800629 gena TNF-α. Bolesnicima s upalnim bolestima crijeva određena je i koncentracija fekalnog kalprotektina (fKal), dok je onima s autoimunim reumatoidnim bolestima klinički odgovor praćen ocjenama aktivnosti reumatoidnih bolesti. Ni koncentracije IFX i ADM kao ni pojavnost i koncentracije protutijela na studirane lijekove nisu se razlikovale ovisno o genotipovima polimorfizama rs361525 i rs1800629 gena TNF-α. Koncentracija CRP nakon 12 mjeseci terapije bila je viša u bolesnika s genotipom GG nego u onih s genotipom GA na položaju -238 gena TNF-α, dok nije bilo razlike u koncentraciji CRP kod različitih genotipova na položaju -308 gena TNF-α. Koncentracija fKal nije se razlikovala ovisno o genotipu polimorfizama rs361525 i rs1800629 gena TNF-α. Remisija je postignuta kod 63 % bolesnika, neovisno o genotipu studiranih polimorfizama. Bolesnici s autoimunim reumatoidnim bolestima genotipa GG u oba ispitivana polimorfizma imali su statistički značajno bolji odgovor na terapiju u odnosu na bolesnike s genotipom GA ili AA. Univarijatnom regresijskom analizom pokazano je da je postizanje terapijske koncentracije IFX i ADM izglednije kod muškaraca, a pojava protutijela na lijekove manje izgledna. U bolesnika s RA izglednija je pojava protutijela na lijekove, a manje izgledno je postizanje terapijske koncentracije lijekova, dok kod ostalih bolesti univarijatnom regresijskom analizom nisu dobiveni statistički značajni omjeri izgleda. Remisiju bolesti može predvidjeti koncentracija CRP 6 i 12 mjeseci nakon terapije, dok se klinički odgovor na terapiju ne može predvidjeti ne temelju genotipa studiranih polimorfizama. Tumor necrosis factor α (TNF-α) inhibitors are effective in the treatment of autoimmune rheumatoid disease (ARD) and inflammatory bowel diseases (IBD), but almost 30 % of patients do not achieve remission of the disease. Objectives of the study were to examine the association of genotypes of -238 G/A (rs361525) and -308 G/A (rs1800629) polymorphisms in TNF-α gene with the clinical and biochemical response to the therapy. The study included 112 patients, of which 66 with IBD and 46 patients with ARD. There was a total of 73 patients on infliximab (IFX) therapy and 39 on adalimumab (ADM) therapy. Patients were followed for 6 to 12 months from the start of biologic therapy. All patients were tested for reactive protein C (CRP), IFX and ADM, and antibodies to these drugs, as well as the genotype polymorphisms rs361525 and rs1800629 of the TNF-α gene. Patients with IBD were also tested for fecal calprotectin (fCal) levels, while those with ARD had a clinical response followed by assessments of rheumatoid disease activity. Concentrations of IFX and ADM after at least 6 months of therapy did not differ depending on genotypes TNF-α gene polymorphisms -238 G/A and -308 G/A. The incidence of antibody development, as well as the concentration of anti-drug antibodies, did not differ depending on tested polymorphisms. After 12 months of therapy, CRP concentration was higher in patients with GG than in patients with GA genotype in the -238 position of the TNF-α gene. fCal concentration did not differ depending on the studied polymorphisms. Remission was achieved in 63 % of patients, with no difference depending on the genotypes. Patients with ARD carrying the GG genotypes in both positions, -238 and -308, had a significantly better response to the therapy compared to patients with GA or AA genotypes. The univariate logistic regression analysis has shown that males are more likely to achieve therapeutic levels of IFX and ADM and less likely to develop antibodies to drugs. The studied polymorphisms were not factors that can predict the clinical response to the therapy. Genotyping of polymorphisms -238 G/A and -308 G/A in the TNF-α gene before the introduction of IFX and ADM therapy does not contribute to the prediction of clinical outcomes monitored by blood concentration of drugs and antibodies to the drugs, or clinical remission of IBD or ARD.

Although self-limiting viral infections are the principal cause of fever in the majority of cases, it is estimated that 5% of febrile children younger than three years of age would have a urinary tract infection (UTI). Despite the increased availability of laboratory testing and development of various clinical scores, there is still no reliable predictor of UTI in children. Recent advancements in the understanding of inflammatory process have highlighted the role of S100 proteins, with many studies suggesting their clinical value as a biomarker of inflammation. This research aims to investigate the possible role of serum calprotectin (sCAL), a heterodimer consisting of S100A8 and S100A9 proteins from S100 family, as a biomarker for bacterial urinary tract infection in children. Patients aged 0-36 months who came to Pediatric Emergency Department of Sestre milosrdnice University Hospital Center with fever ≥38°C, lasting

Although self-limiting viral infections are the principal cause of fever in the majority of cases, it is estimated that 5% of febrile children younger than three years of age would have a urinary tract infection (UTI). Despite the increased availability of laboratory testing and development of various clinical scores, there is still no reliable predictor of UTI in children. Recent advancements in the understanding of inflammatory process have highlighted the role of S100 proteins, with many studies suggesting their clinical value as a biomarker of inflammation. This research aims to investigate the possible role of serum calprotectin (sCAL), a heterodimer consisting of S100A8 and S100A9 proteins from S100 family, as a biomarker for bacterial urinary tract infection in children. Patients aged 0-36 months who came to Pediatric Emergency Department of Sestre milosrdnice University Hospital Center with fever ≥38°C, lasting

Uvod: Entezitisu pridruženi artritis (ErA) posebni je oblik juvenilnog idiopatskog artritisa (JIA) koji predstavlja nediferencirani juvenilni spondiloartritis (jSpA). Uz artritis perifernih zglobova, jedna od najvažnijih značajki jSpA je upala enteza i/ili aksijalnog skeleta. I dok se u odraslih bolesnika sa SpA crijevo sve češće navodi kao polazište i/ ili ishodište subkliničke upale, učestalost i raširenost upalnog procesa u crijevima djece s ErA još uvijek nije poznata, uglavnom zbog izazova vezanih uz provođenje invazivnih pretraga neophodnih za otkrivanje upale crijeva u djece. Cilj našeg istraživanja stoga je bio procijeniti koncentraciju fekalnog kalprotektina (fCAL), surogatnog markera upale crijeva, u djece s različitim oblicima artritisa. Ispitanici i metode: U ovom presječnom istraživanju sudjelovalo je ukupno 71 dijete s postavljenom dijagnozom oligo i poliartikularnog oblika JIA (N=29), ErA (N=26), PsA (N=4) te neupalnim muskuloskeltnim stanjima (N=12). Svi bolesnici s ErA uključeni su neovisno o prisutnosti gastrointestinalnih simptoma, dok su ostali uključeni u slučaju izraženih simptoma. Uz standardne laboratorijske pretrage, svim sudionicima izmjeren je fCAL, a svim bolesnicima s ErA, kao i ostalima koji su se žalili na upalnu bol u leđima, učinjen je MR SIZ- ova. U svih bolesnika s ErA izmjerena je aktivnost bolesti pomoću jSpADA, a u ostalih oligo i poli JIA bolesnika pomoću JADAS-a. Rezultati: Medijan koncentracije fCAL bio je najviši u skupini bolesnika s ErA (33.2 mg/kg, p=0.043), s značajnom razlikom između bolesnika s aktivnom i inaktivnom bolesti (20.0 mg/kg vs 57.4 mg/kg, p=0.01), kao i između bolesnika s prisutnim znakovima upale te bolesnika s urednim nalazom MR-a (22.6 mg/kg vs 54.3 mg/ kg, p=0.048). Koncentracije fCAL nisu se značajno razlikovale između bolesnika koji su koristili i koji nisu koristili NSAIL-ove (23 mg/kg vs 20 mg/kg, p=0.18), mada je uočena slaba koleracija s trajanjem korištenja (r=0.25, p=0.03). Zaključak: Subklinička upala crijeva nije vezana samo uz odrasle bolesnike sa SpA, već i uz djecu s nediferenciranom oblikom jSpA, osobito ako je uz to prisutna aktivna bolest i/ili znakovi upale SIZ-ova na MR-u.

BACKGROUND-AIM: Preanalytical stability for analytes in serous fluids (SF) is largely unknown. Our aim was to evaluate stability of clinically relevant analytes in SF (i.e. pleural and peritoneal effusions) stored under different conditions prior to analysis. METHODS: Leftovers from 20 consecutive SF samples initially referred to our laboratory for routine analysis were separated. Baseline values for total proteins (TP), albumin (ALB), lactate dehydrogenase (LD), cholesterol (CHOL), triglycerides (TRIG), creatinine (CREA), urea, glucose, amylase (AMY) and C-reactive protein (CRP) were measured within 1 hour from sample receipt. Leftover SF samples were then aliquoted in 5 aliquots and stored for 6 hours at room temperature (RT), and 3, 7, 14 and 30 days at -20 °C. At the end of each storage period all analytes were measured. Analytes were measured using the Abbott Architect c8000 (Abbott Laboratories, Abbott Park, USA). Mean bias was calculated for each parameter and respective storage period, and compared to stability limits (SL) set according to CROQALM criteria. Statistical analysis was performed using Medcalc (Ostend, Belgium). P < 0.05 was considered statistically significant. RESULTS: Significant differences comparing all storage periods were observed for LD, CREA, glucose and CRP (P < 0.001). Calculated biases for TP, ALB, CHOL, TRIG, CREA, urea, AMY and CRP in all storage periods tested were below the SL. Glucose and LD were stable for 6 hours at RT, with biases of -3.8 and 0.2%, respectively. Biases exceeding the SL were observed for glucose and LD in SF when stored for 3, 7, 14 and 30 days at -20 °C (i.e. -7.6, -11.5, -17.5 and -27.5% for glucose, and -17.1, -25.5, -30.1 and -40.3% for LD, respectively). CONCLUSIONS: Our results indicate that TP, ALB, CHOL, TRIG, CREA, urea, AMY and CRP may be safely analysed when SF samples are stored up to 6 hours at RT and/or 30 days at -20 °C. However, serous fluid glucose and LD are stable only up to 6 hours stored at RT.

BACKGROUND-AIM: Point-of-care testing (POCT) comprises diagnostic testing usually performed by non-laboratory personnel at the site of the patient (i.e. hospital wards or at home). The comparability of results obtained from left hand (L) vs. right hand (R) capillary sampling samples using POCT is implied. Our aim was to test this hypothesis, i.e. to test if results obtained from L and R hand capillary samples by using a POCT device were comparable. METHODS: Paired capillary samples were taken simultaneously from L and R middle fingers of 21 healthy participants using Greiner bio-one miniCollect safety lancets with puncture depth of 2.00 mm. A volume of 200 μL of capillary blood from each finger was collected using lithium- heparinized Minivette POCT (Sarstedt, Nümbrecht, Germany). Testing was performed using Abbott i-STAT Alinity (Abbott, Abbott Park, USA) POCT analyser and Na, K, Cl, iCa, glucose, urea, creatinine, haematocrit, haemoglobin, pH, PCO2, PO2, TCO2, HCO3-, base excess (BE), sO2, lactate were measured. Statistical analysis was performed using MedCalc statistical software (Ostend, Belgium). Mean biases obtained from L vs. R were compared to CROQALM criteria for respective parameters. RESULTS: No statistical or clinical difference in results obtained after sampling from L and R was found. Calculated biases for each parameter analysed were lower than the criteria previously defined. The biases expressed as mean bias (corresponding criteria) were as follows: pH 0.04% (1%), pCO2 - 0.24% (8%), pO2 2.00% (8%), lactate -4.35% (16%), Na 0.30% (3%), K 1.65% (6%), Cl – 0.15% (4%), urea 0.88% (8%), creatinine 1.19% (9%), glucose - 0.87% (7%), iCa 1.79% (4%), Hct 1.25% (5%), Hb 1.22 (5%). CONCLUSIONS: Results obtained from L and R hand capillary samples using a POCT device were comparable. Thus, capillary sampling might be performed from either hand, interchangeably.

Introduction: According to the tube manufacturers recommended centrifugation conditions of serum samples are 10-15 minutes on 1800-2200 xg. If samples are not properly centrifuged, serum quality could be compromised due to the leftover fibrin in samples and higher degree of hemolyzed samples. The aim of this study was to investigate if shorter centrifugation time affects sample quality. Materials and methods: In Department of Clinical Chemistry, Sestre milosrdnice University Hospital Center serum samples were routinely centrifuged for 10 minutes at 2876 xg on Hettich Rotanta 46RSC (Hettich, Tuttlingen, Germany). In September 2017 for 10 days, time of centrifugation was reduced to 5 minutes. Samples with leftover fibrin were recorded from Architect c8000 and i2000 analyzers (Abbott, Abbott Park, IL, USA) as aspiration errors. Index of hemolysis (H) was measured on Architect c8000 for all serum samples. Samples with H index>0.5 were considered as hemolyzed. Proportion of samples with leftover fibrin and hemolysis was calculated against the total number of samples received from the laboratory information system. Results are presented as numbers and percentages. Proportions of hemolyzed and samples with aspiration errors were compared for 10 minutes and 5 minutes period with Chi-squared test for comparison of two proportions. Excel and MedCalc (v.11.5.1.0, Ostend, Belgium) were used for all calculations. P value

Introduction: Parathyroid hormone (PTH) is peptide responsible for regulating calcium blood concentrations and is known to have very short half-life. Croatian national guidelines for venipuncture state that samples should be placed on ice immediately after drawing when PTH is ordered. Aim of our study was to investigate PTH stability in serum samples immediately and 4 hours after venipuncture with and without ice using two methods. Materials and methods: This study was carried out in Department of Clinical Chemistry, Sestre milosrdnice University Hospital Centre, Zagreb, Croatia. Twenty outpatients participated and for each patient, two serum blood samples were drawn in tubes with serum clot activator without gel separator (Vacuette, GrainerBio- One, Kremsmünster, Austria). One tube was immediately placed on ice and second was left on room temperature. After 30 minutes, samples were centrifuged at 1800xg for 10 minutes, PTH concentration was measured on Abbott Architect i2000SR (Abbott, Abbott Park, IL, USA) and Roche Cobas e411 (Roche, Mannheim, Germany) using original reagents (second generation PTH immunoassay). Samples which were not drawn on ice were left for 4 hours on room temperature and analyzed again on both analyzers. For statistical evaluation Bland Altman analysis was done using MedCalc statistical software (MedCalc software, Ostend, Belgium). Constant and proportional bias was evaluated by comparing 95% confidence interval limits with 0. Results: Our results have shown that there was no statistical significant difference in PTH concentration from samples drawn on ice and those left on room temperature before centrifugation on both analyzers. However, for samples left 4 hours at room temperature, Bland-Altman analysis showed constant and proportional statistical significant difference for both methods (7.8 pg/mL, 11.4% for Abbott and 3.8 pg/mL, 6.9% for Roche, respectively). Conclusion: Samples do not have to be placed on ice immediately after sampling, however, samples have to be analyzed within 4 hours.

Introduction: in the past few years, various indicators of disease activity in juvenile idiopathic arthritis (JIA) patients have been investigated, allowing for the interpretation of different aspects of underlying inflammatory process (e.g. clinical, immunological, radiological etc.). Nevertheless, there is still evident lack of satisfactory support in diagnostic and prognostic evaluations in everyday clinical practice, focusing research activities on discovery of adequate biomarker that would support initial diagnosis and allow feasible disease monitoring. While growing number of evidence indicates phagocytic S100 proteins, like MRP8/14 complex (i.e. calprotectin), can be used to detect subclinical inflammatory activity in systemic JIA, their performance in other forms of JIA is still debatable, while in acute infectious diseases it is almost unknown. Objectives: compare serum calprotectin (sCAL), CRP and PCT levels in patients with various forms of non-systemic JIA and previously healthy children with acute febrile illness lasting

Laboratories often modify procedures recommended by the European Urinalysis Guidelines for urine sediment analysis. The aim of this study was to compare the recommended protocol with our routine laboratory procedure and to evaluate the possible impact of modifications in the relative centrifugal force, type of tube, method of supernatant aspiration and urine volume on patient’s results. Firstly, relative centrifugal force was investigated using 20 pairs of samples examined after centrifugation at 400xg and 1358xg. In phase two, 110 samples were examined, paired as: round bottom vs conical tube (N = 46), decanting vs suction of supernatant (N = 100) and 10 mL vs 5 mL of urine sample (N = 101). The number of erythrocytes, leukocytes and squamous epithelial cells was significantly lower after centrifugation at 400xg (P = 0.001, 0.002 and 0.004, respectively). The number of leukocytes was significantly lower in conical tubes (P = 0.010), after the suction of supernatant (P = 0.045) and in 5 mL urine (P < 0.001). The number of squamous epithelial cells was significantly lower after the suction of supernatant (P < 0.001) and in 5 mL urine (P < 0.001). The number of erythrocytes (P < 0.001), total non-hyaline casts (P < 0.001) and the frequency of granular casts (P = 0.039) was significantly lower in 5 mL urine. Lower results of leukocytes, erythrocytes, squamous cells and non-hyaline casts were recorded in recommended procedures (centrifugation at 400xg, suction of supernatant, conical tube, 5 mL of sample) than in routine procedure (centrifugation at 1358xg, decanting of supernatant, round bottom tube, 10 mL) used in our laboratory.

Introduction: Manufacturer declares the stability of control sample in refrigerator at 2 - 8 °C, while stability on room temperature is not described. Often during routine work, control sample stays longer at room temperature and it is not evident can such sample be used for analyte measurement. The aim of the study was to examine the stability of control sample during 14 hours at 1-hour time intervals at room temperature in the light and in the dark. Materials and methods: A control sample of Multichem S level 3 (Techno-path Manufacturing Ltd, Ireland) was used for analysis. Analytes were measured on the Abbott Architect c8000 analyzer (Abbott Laboratories, Abbott Park, USA): albumin, ALT, amylase, AST, total bilirubin, direct bilirubin, Ca, CK, Cl, creatinine, enzymatic creatinine, CRP, ethanol, glucose, K, lactate, LDH, lipase, phosphates, total proteins, urate and urea using Abbott’s original reagents. One aliquot of control sample was stored in a transparent tube with a stopper in the light throughout the test period, while another aliquot was stored in a dark bottle sealed in a cupboard that did not reach the light. Samples were analyzed every hour in the period from 9 am to 23 pm. For each time interval, the bias was calculated by the initial value obtained at 9 hours. Acceptance criteria for imprecision are downloaded from the Westgard Desirable Biological Variation Database web page (https://www.westgard. com/biodatabase1.htm#1). Results: Stability of all tested analytes in darkness has fully met the eligibility criteria throughout the entire test interval. Stability in the light did not satisfy calcium after the third hour of testing interval. The deviation was 2.5% and the permitted criteria was 1.05%. Conclusion: All analytes are stable for 14 hours in light and dark, except for calcium which is stable 3 hours in the light.

Background: Feacal calprotectin as a non- invasive marker of inflammatory bowel disease (IBD) is routinely measured in our laboratory with fluoroenzymatic immunoassay (FEIA, Thermo Fisher Scientific) on Phadia 100 analyzer. The aims of this study were: i) verification of fCAL turbo test (Bühlmann) on ARCHITECT c8000 (Abbott Diagnostics) using particle enhanced turbidimetric immunoassay (PETIA) and ii) verification of calprotectin stability specified by manufacturer in faecal extract obtained with CALEX® Cap device extraction tube (Bühlmann). Methods: To evaluate assay imprecision, commercial quality control sample and patient faecal extract were run in triplicate for five days. Comparison of FEIA and PETIA assays was made on 40 faecal extracts with calprotectin concentration throughout entire measuring range. Carry-over was calculated by measuring calprotectin in sample with high concentration (in duplicate) followed with measurement of calprotectin in sample with low concentration (in triplicate). Verification of stability was performed by measuring calprotectin in four faecal extracts (27–1035 mg/kg) stored at 4-8 C during 6 days. Allowable bias was set at 30%, according to Labquality external quality assessment criteria. Results: Interlaboratory imprecision for fCAL turbo test was 2.41% for mean calprotectin concentration of 123.9 mg/ kg and 5.48% for 74.5 mg/kg. Passing-Bablok regression analysis showed statistically significant proportional difference [y=0.51(95%CI -35.66 - 0.61) + 1.83(95%CI 1.33 - 3.41)x] and Bland-Altman analysis showed both proportional and constant difference between two methods. Calprotectin proved to be stable in faecal extracts kept at 4-8 C during 6 days in samples with concentration at cut off value (50 mg/kg) and higher, with mean biases 2.67–21.63%. Sample with concentration lower than cut off had mean bias 35.1% but it has no influence on clinical decision. Calculated carry-over effect was 0.10%, in accordance with manufacturer's claim. Conclusion: fCAL turbo test has satisfactory imprecision and minimum carry-over effect. Calprotectin in faecal extract was proved to be stable according to manufacturer specification. Comparison study showed that FEIA and PETIA methods cannot be used interchangeably.

BACKGROUND-AIM: iChem Velocity (iCV) test strips manufacturer claims that ascorbic acid (AA) concentrations greater than 20 mg/dL could interfere with glucose, nitrite and blood. On the other hand, the manufacturer of Combur10Test®M (C10M) claims that AA does not interfere with glucose and blood. The aim of the study was to evaluate AA impact on the glucose, hemoglobin, nitrite and bilirubin measured with iCV and C10M urine strips. METHODS: Iris iChemVELOCITY (Iris Diagnostics, Chatsworth, USA) and Cobasu411 (Roche, Mannheim, Germany) were used to analyze associated test strips. Stock solutions of each tested analyte were prepared. The materials used were: anhydrous glucose (Kemig d.o.o), hemoglobin (whole blood) sodium nitrite (Kemika d.o.o), bilirubin (Sigma/Aldrich) and vitamin C500 (Worwag pharma GmbH&Co.KG). Specific analyte concentrations (glucose: 2.7 ; 5.8 and 16.8 mmol/L, hemoglobin: 0.03 ; 0.06 and 0.10 mg/dL, nitrite: 0.1 ; 0.2 mg/dL, bilirubin: 37 ; 70 umol/L) were prepared using negative urine pool sample and AA solution in order to achieve specific concentration in each tested sample (0 ; 20 ; 30 ; 50 ; 100 ; 200 ; 500 mg/dL). Interference was confirmed if the result was changed in comparison with pool without AA. RESULTS: AA interferes with glucose measured on C10M at 50 mg/dL and above 200 mg/dL on iCV, with hemoglobin at 20 mg/dL on both tested strips, with nitrite at 50 mg/dL on iCV and above 200 mg/dL on CM10 and with bilirubin at 50 mg/dL on both tested strips. iCV test strips are the most impacted by AA when hemoglobin, bilirubin and nitrite are tested and C10M test strips are the most impacted by AA interference when glucose, hemoglobin and bilirubin are tested. CONCLUSION: Despite manufacturers` claims our results demonstrate negative effect on tested analytes at varying concentrations of specific analyte and AA. That is why the possibility of the AA detection in urine offered by iCV could be of great help in order to avoid misdiagnosis.

Serum indices, hemolysis (H), icteria (I), lipemia (L) are determined automatically on chemistry analyzers. HIL absorbance spectra patterns overlap which could result with HIL cross-reactivity when multiple interferences are present. We aimed to investigate interference cross-reactivity and to compare cross-reactivity of indices between three different biochemistry analyzers. Study included Abbott Architect c8000, Beckman Coulter AU5800 (BC) and Roche Cobas 6000. For each interference, 6 increasing levels of interfering substances were added to serum pool (hemolysis: 0.3-10 g/L hemoglobin (Hb) by needle aspiration, icteria: 35-675 µmol/L of dissolved bilirubin, lipemia: 0.1-1.4 g/L of Intralipid). HIL indices were measured in duplicate before and after addition of second interferent (approximate values H=5 g/L, I=400 µmol/L, L=1 g/L of Intralipid) and biases between those measurements were calculated. BC provides semiquantitative results (5 categories), while Abbott and Roche express indices as corresponding concentrations: hemoglobin (g/L) for H, bilirubin (μmol/L) for I and Intralipid (g/L) for L index. Less than 10% was considered acceptable bias for Abbott and Roche, and for BC agreement of result category. Hemolysis decreased I index on Abbott and Roche (for 20% and 14%, respectively). On BC, hemolysis increased I index. L index on Abbott was higher (for 35-180%), while on Roche and BC, L index was lower (11-32% for Roche) after adding free Hb. Adding bilirubin had no effect on H index on Abbott, while on Roche and BC, H index was higher (13-35%). Bilirubin also changed L index for more than 30% on all analyzers. I index on Abbott and Roche was lower after adding Intralipid (mean bias 75% and 28%, respectively). Lipemia interfered with H index on all three analyzers (for approximately 14%). Almost all tested interference combinations showed cross- reactivity. Serum indices could be erroneous if more than one interfering substances is present in serum sample.