Biological variation of serum neopterin concentrations in apparently healthy individuals.

OBJECTIVES: The aims of this study were to determine the biological variation (BV), reference change value (RCV), index of individuality (II), and quality specifications for serum neopterin concentrations; a measurand provided by clinical laboratories as an indicator of cellular immunity. METHODS: The study delivered serum samples collected for 10 consecutive weeks from 12 apparently healthy individuals (3 male, 9 female). Serum neopterin concentrations were measured using high-performance liquid chromatography with fluorometric detection. The data analysis was performed using an online statistical tool and addressed published criteria for estimation of biological variation. RESULTS: The mean neopterin concentration was 5.26 nmol/L. The within-subject biological variation (CVI) with 95 % confidence interval (CI) of neopterin serum concentrations was 11.54 % (9.98-13.59), and the between-subject biological variation (CVG) with 95 % CI was 43.27 % (30.52-73.67). The neopterin asymmetrical RCV was -24.9 %/+33.1 %, and the II was 0.27. The desirable quality specifications for neopterin were <5.77 % for precision, <11.20 % for bias, and <20.72 % for total allowable error (TEa). When analytical variation was used instead of CVI to calculate TEa, the desirable TEa was <18.39. CONCLUSIONS: This study determined BV data for neopterin, an indicator of cell-mediated immune response. Asymmetric RCV values, of 24.9 % decrease or a 33.1 % increase between consecutive measurements indicate significant change. The II of 0.27 indicates a high degree of individuality, therefore that it is appropriate to consider the use of personal reference data and significance of change rather than the reference interval as points of reference for the evaluation of neopterin serum concentrations.

Effects of specimen haemolysis on complete blood count results by Abbott Alinity hq System.

INTRODUCTION: The current study aimed to assess the interference of in vitro haemolysis on complete blood count (CBC) using Abbott Alinity hq system, and to determine which haemolysis levels affect the reliability of sample results. MATERIALS AND METHODS: Blood samples obtained from 25 volunteers in K3-EDTA tubes were divided into four aliquots. The first aliquot was not subjected to any intervention. The second, third and fourth aliquots were passed through a fine needle 2, 4 and 6 times, respectively. Complete blood count was performed by multi-angle polarized scatter separation technology and haemolysis index (HI) was assessed from the plasma samples separated by centrifugation. Five groups were formed according to the HI values. The percentage biases between the results of non-haemolysed and haemolysed groups were compared with the desirable bias limits from The European Federation of Clinical Chemistry and Laboratory Medicine database and reference change values (RCVs). RESULTS: In groups 1 to 4, the effects of haemolysis on CBC parameters were acceptable comparing to the analytical bias except for lymphocytes (7.26%-7.42%), MCH (2.59%), and MCHC (0.47%-2.81%). Results of group 5 (gross haemolysis) showed decreases in HCT(- 4.56%), RBC (- 4.07%) count and increase in lymphocyte (11.60%) count higher than the analytical performance specifications. Moreover, variations in MCH (4.65%) and MCHC (5.24%) were exceeding the RCVs. CONCLUSIONS: Gross haemolysis (haemoglobin concentration > 10 g/L) is likely to produce unreliable CBC results on non-pathological samples. Further studies including pathological specimens are needed.

BTD Gene Mutations in Biotinidase Deficiency: Genotype-Phenotype Correlation.

OBJECTIVE: To identify the biotinidase (BTD) gene mutations in patients with biotinidase deficiency in our region; and to determine the phenotype-genotype correlations in the presence of clinical findings. STUDY DESIGN: Descriptive study. PLACE AND DURATION OF STUDY: Department of Medical Genetics and Pediatric Metabolism Outpatient Clinic, Faculty of Medicine, Harran University, between January 2018 and June 2020. METHODOLOGY: Two hundred and nine patients, who were found positive for biotinidase deficiency in heel blood screening, were included. Genomic DNA was isolated from peripheral blood. Next-generation DNA sequencing analysis was performed using primers covering the exon regions of the BTD gene. The results were analysed by the mutation surveyor programme. RESULTS: The most common mutation was c.1330 G>C (p.D444H) and the second most common mutation was c.470 G>A (p.R157H). The majority of the mutations are missense; and they are especially located in the exon 4. The most frequent mutations were found to be D444H and R157H with a rate of 66.66% in symptomatic patients. CONCLUSION: Common mutations in BTD deficiencies were indentified. Associating them with phenotype-genotype data will assist clinicians in better genetic counselling and management in the future by implementing prevention programmes. Key Words: Biotinidase deficiency, BTD gene, Newborn screening, Inherited metabolic disease, Newborn screening programme.

Telomere Length and Oxidative Stress in Patients with ST-Segment Elevation and Non-ST-Segment Elevation Myocardial Infarction.

PURPOSE: The telomere length is shown to act as a biomarker, especially for biological aging and cardiovascular diseases, and it is also suggested that with this correlation, increased exposure to the oxidative stress accelerates the vascular aging process. Therefore, this study aims to understand the correlation between the plasma oxidative stress index (OSI) status and leukocyte telomere length (LTL) and cardiologic parameters between the ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI) groups. METHOD: One hundred one newly diagnosed patients with STEMI (n = 55) and NSTEMI (n = 46) were included in the study, along with 100 healthy controls who matched the patients in terms of age and gender. Plasma total antioxidant status (TAS), total oxidant status (TOS), and LTL were measured. RESULTS: When LTL, TAS, TOS, and OSI values were evaluated between the patient and control group, OSI (p = 0.000) and LTL (p = 0.05) values were statistically significant in the patient group compared to the control group. Evaluation was conducted to understand whether there is a difference between the STEMI and NSTEMI groups. The plasma OSI (p = 0.007) and LTL (p = 0.05) were found to be significantly lower in STEMI patients. However, LTL and OSI results were not statistically significant in NSTEMI patients. CONCLUSION: This is the first study evaluating telomere length and oxidative stress in STEMI and NSTEMI patients in Turkey. Our results support the existence of short telomere length in STEMI patients. Future studies on telomere length and oxidative stress will support the importance of our findings.

Evaluation of the efficiency of serum biotinidase activity as a newborn screening test in Turkey.

OBJECTIVES: Biotinidase Deficiency (BD) is an autosomal recessive metabolic disorder. However, the relationship between genotype and biochemical phenotype has not been completely elucidated yet. But still, some mutations are accepted to be associated with profound or partial deficiency. We aimed to evaluate the results of biochemical enzyme activity in accordance with the presence of genetic mutations and investigate the correlation between genotype and biochemical phenotype together in the study. METHODS: This retrospective study was carried out using data from medical records of 133 infants detected by the newborn screening followed by serum biotinidase activity (BA) detection with semi-quantitative colorimetric method. Mutation analysis was performed to confirm the diagnosis. In addition, the expected biochemical phenotype based on the known mutant alleles were compared with the observed biochemical phenotype. RESULTS: When confirmed with mutation analysis results, the diagnostic sensitivity and specificity of serum BA with spectrophotometric method was 93.1% and 95.1%, respectively. In 93.98% of the cases conformity was observed between the biochemical phenotype and the genotype. The c.1330 G>C(p.D444H) and c.470 G>A (p.Arg157His) were the most common allelic variants with frequencies of 63.69% and 33.75%, respectively. CONCLUSIONS: The diagnostic test is supposed to have a high sensitivity to identify asymptomatic BD patients. Apparently healthy cases with almost normal enzyme activity and a variant allele in the genetic analysis were reported to present symptoms under stress conditions, which should be kept in mind. This study can be accepted as an informative report as it may contribute to the literature in terms of the allelic frequency and determination of the relation between genotype and biochemical phenotype. Also, method verification including the assessment of possible effects of non-genetic factors on BA according to the certain mutation types is warranted.

Relationship Between Cognitive Functions and Insulin-degrading Enzyme in Individuals With Prediabetes.

BACKGROUND: Individuals with diabetes can develop cognitive impairment due to dysfunction of glucose metabolism; however, it remains unclear whether cognition becomes altered in the prediabetic stage. Substantial evidence links cognitive impairment in diabetes to aberrant serum insulin-degrading enzyme (s[IDE]) levels. This relationship remains to be investigated in individuals with prediabetes. OBJECTIVE: To investigate the relationship between cognitive function and s[IDE] levels in individuals with prediabetes. METHOD: The study group consisted of 47 individuals who had been diagnosed with prediabetes and 41 healthy controls. Cognitive functions were evaluated using the Montreal Cognitive Assessment (MoCA), and s[IDE] levels were measured using enzyme-linked immunosorbent assay. RESULTS: The MoCA total scores and s[IDE] levels of the individuals with prediabetes were significantly lower (P = 0.001, 0.006) than those of the controls, and the MoCA Attention measure of the individuals with prediabetes was also very low (P = 0.001). To determine cognitive impairment, we divided the prediabetics into two subgroups according to the MoCA cutoff value. Scores on all of the MoCA tests were significantly lower in the group with mild cognitive impairment (P < 0.05). There was no correlation between MoCA scores and s[IDE] levels (P > 0.05), but serum-fasting glucose levels showed a negative correlation with MoCA scores (P < 0.05, ρ = -0.287). CONCLUSION: Evidence of mild cognitive impairment was high in the individuals with prediabetes and showed a negative correlation with serum-fasting glucose levels but not with s[IDE] levels.

The relationship between oxidative stress and preeclampsia. The serum ischemia-modified albumin levels and thiol/disulfide homeostasis.

OBJECTIVE: Preeclampsia (PE) is a dangerous complication of pregnancy and still a major cause of maternal-fetal morbidity and mortality. Its etiology remains largely unknown, but researchers have suggested oxidative stress-mediated inflammation for the same. The purpose of this study is to investigate the relationship between oxidative stress and PE as well as the usability of oxidative stress indicators such as serum ischemia-modified albumin (IMA) levels and thiol/disulfide balance in the prediction of PE. MATERIALS AND METHODS: The study included 47 pregnant women with PE and 57 healthy pregnant women. We measured their serum IMA, native thiol, total thiol, and disulfide levels. Additionally, we determined the optimal cutoff values via the receiver operating characteristic curve analysis. RESULTS: There were no differences between the two groups with respect to the maternal age, body mass index, gravida, and parity. The native and total thiol levels were found to be low when the disulfide and IMA levels were high in the patients with PE (p<0.05). When the IMA level was corrected by the albumin level (IMAR), the significant difference between the two groups disappeared. We also found that the native and total thiol concentrations were correlated with the systolic and diastolic blood pressures. The optimal cut-off values calculated for the prediction of PE were as follows: 178.45 µmol/L (with sensitivity of 72% and specificity of 83%) for native thiol, 232.55 µ mol/L (with a sensitivity of 75% and specificity of 85%) for total thiol, and 29.05 µmol/L (with sensitivity of 65% and specificity of 72%) for disulfide. CONCLUSION: The balance of thiol/disulfide may play a role in the pathogenesis of PE and could be used as a biological marker for PE.

Relationship of serum calprotectin, angiopoietin­1, and angiopoietin­2 levels with coronary collateral circulation in patients with stable coronary artery disease.

BACKGROUND: In patients with chronic stable coronary artery disease (CAD), well­developed coronary collateral circulation (CCC) is known to reduce long­term mortality. AIMS: The objective of this study was to determine the relationship of serum calprotectin (S100A8 / S100A9), angiopoietin­1 (Ang­1) and angiopoietin­2 (Ang­2) concentrations with CCC in patients with stable CAD. METHODS: This prospective cross­sectional study included 147 patients with stable angina pectoris. The Cohen-Rentrop classification was used to assess CCC. Patients were divided into 2 groups: with poor CCC (Cohen-Rentrop score, 0-1; n = 79) and with good CCC (Cohen-Rentrop score, 2-3; n = 68). Serum calprotectin, Ang­1, and Ang­2 concentrations were compated between groups. RESULTS: Compared with the group with good CCC, serum calprotectin and Ang­1 levels were higher (P <0.01 and P <0.001, respectively), while serum Ang­2 levels were lower (P <0.01) in the poor­CCC group. C­reactive protein levels showed a moderate positive correlation with calprotectin levels (r = 0.359; P <0.001). In a multivariate regression analysis, only calprotectin (P <0.05) and Ang­1 (P <0.05) were found to be independent predictors of good and poor CCC. CONCLUSIONS: Our study showed that Ang­2 levels were lower, while serum calprotectin and Ang­1 levels were higher, in patients with stable CAD and poor CCC regardless of the complexity and severity of coronary arteriosclerosis. If these results are confirmed in future studies, calprotectin may be considered a useful biomarker for guiding anti­ischemic treatment.

Determining biological variation of serum parathyroid hormone in healthy adults.

INTRODUCTION: Measurement of parathyroid hormone (PTH) is essential in the investigation and management of calcium metabolism disorders. To assess the significance of any assay result when clinical decision making biological variation (BV) of the measurand must be taken into consideration. The aim of the present study is determining the BV parameters for serum PTH. MATERIALS AND METHODS: Blood samples were taken at weekly intervals from 20 healthy subjects for ten weeks in this prospective BV study. Serum "intact PTH" concentrations were measured with electrochemiluminescence method. Biological variation parameters were estimated using the approach proposed by Fraser. RESULTS: The values of within-subject biological variation (CVI), between-subject biological variation (CVG), analytical variation (CVA), reference change value (RCV) and individuality index (II) for serum PTH were 21.1%, 24.9%, 3.8%, 59.4% and 0.8%, respectively. Within-subject biological variation and CVG were also determined according to gender separately; 18.5% and 24.0%; 26.2% and 18.6% for male and female, respectively. Calculated desirable precision and bias goals were < 10.6% and < 6.3%, respectively. CONCLUSION: This study may contribute to BV data on serum PTH as it includes a sufficient number of volunteers from both genders over an acceptable period of time. We do not recommend the usage of population-based reference intervals for serum PTH concentrations. Reference change value may be helpful for the evaluation of serial serum PTH results. Nonetheless, evaluation of data according to gender is necessary when setting analytical performance specifications.

Calculation of Biological Variation Components and Reference Change Value for Serum Copper and Zinc.

BACKGROUND: Zinc and copper are among the most important trace elements. Deficiencies of these trace elements cause a wide variety of disorders. The present study aims to report the definitive assessment of biological variation (BV) parameters for these elements as within-subject BV (CVI), between subject BV (CVG), index of individuality (II), and reference change value (RCV) in a Turkish cohort study group. METHODS: Ten blood specimens were collected weekly from 20 healthy volunteers (13 women, 7 men) for 10 weeks. Collected sera were stored at -80°C until the time of analysis. Serum zinc and copper levels were analyzed with atomic absorption spectrometry and ANOVA test was used to calculate the variations. RESULTS: The CVI and CVG for zinc were 6.26% and 23.27%, respectively. Analytical variation (CVA) was calculated as 4.24%. II and RCV for zinc were calculated as 0.26 and 21.51%, respectively. The CVI and CVG for copper were 6.05% and 19.64%, respectively. CVA was calculated as 4.24%. II and RCV for copper were calculated as 0.31 and 20.47%, respectively. CONCLUSIONS: Since II values were less than 0.6 for both analytes, the reference values will be of little use. RCV might be preferred for better evaluation instead.

Serum asymmetric dimethylarginine and nitric oxide levels in Turkish patients with acute ischemic stroke.

BACKGROUND: Nitric oxide synthase (NOS) is present in the brain and cerebral arteries and it enables the synthesis of nitric oxide (NO), which plays a critical role in brain perfusion. Asymmetrical dimethylarginine (ADMA) is an endogenous NOS inhibitor. OBJECTIVES: The aim of this study was to evaluate serum ADMA levels, which are an indicator of endothelial dysfunction of the renal functions in patients with acute ischemic stroke, and to determine whether there is a possible correlation between ADMA and NO levels and the l-arginine-to-ADMA ratio. MATERIAL AND METHODS: Fifty-two patients (22 male and 30 female; mean age: 75.2 ±10.1 years) with a diagnosis of acute ischemic stroke in the first 24 h post-stroke and 48 healthy individuals (controls; 13 male and 35 female; mean age: 60.1 ±7.92 years) were included in this study. The risk factors recorded and evaluated were age and gender of the patients, serum lipid levels, serum ADMA levels, nitrate-to-nitrite ratios, l-arginine, l-arginine-to-ADMA ratios, sedimentation rate, C-reactive protein (CRP), urea and creatinine levels, and glomerular filtration ratio (eGFR). RESULTS: The mean serum ADMA level was 0.48 ±0.23 µM for the patients and 0.36 ±0.18 µM for the controls. The mean NO level was 2.78 ±0.59 µM for the patient group and 4.49 ±2.84 µM for the controls. The ADMA levels for the patient group were significantly higher than for the control group (p = 0.011); the NO levels for the patients were significantly lower than for the controls (p < 0.001). The logistic regression method demonstrated that ADMA and NO levels may be independent risk factors for the patient group, and the receiver operating characteristic (ROC) curve analysis showed that both of these variables were discriminative risk factors. CONCLUSIONS: An increased serum level of the NOS inhibitor ADMA was found to be a possible independent risk factor for ischemic stroke.

Serum S100B, NSE, and GRIA1 levels as neurological biomarkers in lead exposure

Background/aim: The central nervous system is one of the major targets in lead exposure. Biomarkers for the diagnosis and follow-up of lead exposure have not been identified. In this study, serum S100B, neuron-specific enolase (NSE), and glutamate receptor 1 (GRIA1) levels were determined as possible biomarkers for lead neurotoxicity. Material and methods: Twenty-five subjects with chronic lead exposure and 25 controls were included in the study. NSE and S100B were measured by electrochemiluminescence immunoassay with a Cobas E601 analyzer. GRIA1 levels were measured with an ELISA kit using a quantitative sandwich enzyme immunoassay technique. Results: GRIA1 levels were significantly higher in the lead exposure group than in the control group. No significant differences for NSE, S100B, ALT, AST, or creatinine in sera were found between lead exposure and control groups. Conclusion: Subjects with chronic lead exposure are found to have increased glutamate receptor levels and do not seem to have glial or neuronal damage, which can be demonstrated with the elevation of NSE and S100B levels. GRIA1 levels might be used as a biomarker for the neurotoxicity of lead.

Comparison of the effect of gel used in two different serum separator tubes for thyroid function tests.

BACKGROUND: Selection and verification of blood collection tubes is an important preanalytical issue in clinical laboratories. Today, gel tubes are commonly used with many advantages, although they are known to cause interference in immunoassay methods. In this study, we aimed to compare SSTs of two different suppliers (Ayset clot activator & Gel and Becton Dickinson (BD) Vacutainer SST II advance) with reference tubes and evaluate the effect of storage time in terms of commonly used endocrine tests such as thyroid-stimulating hormone (TSH), free thyroxine (fT4), and free triiodothyronine (fT3). METHODS: Fifty-five volunteers were included in the study. Samples were taken into three different tubes and analyzed for serum TSH, fT4, and fT3 on Architect ci8200 Immunoassay System. Clinical decision levels were estimated using total allowable error (TEa). RESULTS: No difference was found between tubes in terms of TSH, fT3, and fT4 levels. From a statistical standpoint, TSH and fT4 levels were no longer stable during 24, 48, and 72 hours storage time periods. However, their variations were not clinically significant. CONCLUSION: Ayset clot activator & Gel tubes and BD Vacutainer SST II advance tubes have comparable results with glass tube in terms of TSH, fT3, and fT4 levels on Architect ci8200 Immunoassay Systems. From a clinical standpoint, serum TSH, fT4, and fT3 concentrations may be considered as stable when storing these tubes over 72 hours.

Comparison of vacuum and non-vacuum urine tubes for urinary sediment analysis.

Urine collection systems with aspiration system for vacuum tubes are becoming increasingly common for urinalysis, especially for microscopic examination of the urine. In this study, we aimed to examine whether vacuum aspiration of the urine sample has any adverse effect on sediment analysis by comparing results from vacuum and non-vacuum urine tubes. The study included totally 213 urine samples obtained from inpatients and outpatients in our hospital. Urine samples were collected to containers with aspiration system for vacuum tubes. Each sample was aliquoted to both vacuum and non-vacuum urine tubes. Urinary sediment analysis was performed using manual microscope. Results were evaluated using chi-square test. Comparison of the sediment analysis results from vacuum and non-vacuum urine tubes showed that results were highly concordant for erythrocyte, leukocyte and epithelial cells (gamma values 1, 0.997, and 0.994, respectively; p < .001). Results were also concordant for urinary casts, crystals and yeast (kappa values 0.815, 0.945 and 1, respectively; p < .001). The results show that in urinary sediment analysis, vacuum aspiration has no adverse effect on the cellular components except on casts.

Stability of urine specimens stored with and without preservatives at room temperature and on ice prior to urinalysis.

OBJECTIVES: Laboratories determine the most appropriate approach for the collection and transport of urine specimens. We investigated the effect of a chlorhexidine-based preservative tube on sample stability, compared the results of refrigerated polystyrene tubes with no additives, and investigated the effect of temperature on the performance of preservative tubes. DESIGN AND METHODS: Fresh urine specimen (n=48) aliquots in BD Vacutainer® Plus Urinalysis Preservative Tubes and polystyrene tubes were analyzed on an Iris Diagnostics iQ200. Samples in polystyrene tubes were refrigerated for 4 and 8h. Four aliquots in preservative tubes were kept at room temperature for 4, 8, 24, and 72h, while two aliquots were kept on ice for 4 and 8h. RESULTS: There was good agreement for all chemistry and microscopy parameters with the exceptions of white blood cells (WBCs) at 24 and 72h and red blood cells (RBCs) at 72h. Preservative tubes on ice showed a significant decrease in concordance of WBCs and calcium oxalate (CaOx) parameters compared with the results at room temperature. Results of refrigerated polystyrene tubes showed good agreement with the exceptions of WBC clumps and amorphous crystal at 8h. CONCLUSIONS: A chlorhexidine-containing preservative tube seems advantageous for urine sample transport from outside healthcare services. A preservative tube offers comparable results with urine samples kept in a refrigerator for 4-8h for the majority of parameters. Keeping samples at room temperature is recommended when preservative tubes are used because ice produces a negative effect on WBCs and CaOx.

An alternative marker of low-density lipoprotein cholesterol in coronary artery disease: non-high-density lipoprotein cholesterol.

BACKGROUND/AIM: Dyslipidemia is one of the most important risk factors for coronary artery disease (CAD), and low-densitylipoprotein cholesterol (LDL-C) is used to measure dyslipidemia. Non-high-density lipoprotein cholesterol (non-HDL-C) seems to be an alternative parameter to LDL-C as it is not influenced by triglyceride (TG) levels. The aim of this study is to compare non-HDL-C and LDL-C levels as risk markers in CAD patients. MATERIALS AND METHODS: One hundred and ten CAD patients and 42 individuals with normal coronary angiography results were included in this study. Patients were divided into 2 groups: TG < 200 mg/dL (n = 75) as group 1 and TG > 200 mg/dL (n = 35) as group 2. Total cholesterol (TC), TG, and HDL-C levels were analyzed with a Roche Modular P800 autoanalyzer. LDL-C and non-HDL-C levels were calculated. RESULTS: There were statistically significant differences in TC, TG, HDL-C, and non-HDL-C levels when the groups were compared. Non-HDL-C levels of group 2 were statistically higher than those of group 1 and the control group. There was no significant difference in LDL-C levels between the groups. CONCLUSION: Non-HDL-C levels are better risk markers than LDL-C levels, especially in patients with TG > 200 mg/dL, and non-HDL-C levels should be taken into consideration when evaluating the risk of CAD.