The effect of storage time and freeze-thaw cycles on the stability of serum samples

Introduction: Optimal storage of serum specimens in central laboratories for a long period for multicenter reference interval studies, or epidemiologic studies remains to be determined. We aimed to examine the analytical stability of chemistry analytes following numerous freeze-thaw and long term storage. Materials and methods: Serum samples were obtained from 15 patients. Following baseline measurement, sera of each subject were aliquoted and stored at -20 ˚C for two experiments. A group of sera were kept frozen for up to 1, 2 and 3 months and then analyzed for stability. The other experiment consisted of one to ten times of freeze and thaw cycles. Total of 17 chemistry analytes were assayed at each time point. The results were compared with those obtained from the initial analysis of fresh samples. Median or mean changes from baseline (T0) concentrations were evaluated both statistically and clinically according to the desirable bias. Results: Of the analytes studied, aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), gamma-glutamyl transferase (GGT), direct bilirubin, glucose, creatinine, cholesterol, triglycerides, high density lipoprotein (HDL) were stable in all conditions. Blood urea nitrogen (BUN), uric acid, total protein, albumin, total bilirubin, calcium, lactate dehydrogenase (LD) were changed significantly (P < 0.005). Conclusions: As a result, common clinical chemistry analytes, with considering the variability of unstable analytes, showed adequote stability after 3 months of storage in sera at -20 °C, or up to ten times of freeze-thaw cycle. All the same, such analysis can only be performed for exceptional cases, and this should be taken into account while planning studies

Effects of hemolysis interference on routine biochemistry parameters

Introduction: Hemolysis is still the most common reason for rejecting samples, while reobtaining a new sample is an important problem. The aim of this study was to investigate the effects of hemolysis in different hemolysis levels for mostly used biochemical parameters to prevent unnecessary rejecti-ons. Materials and methods: Sixteen healthy volunteers were enrolled in the study. Four hemolysis levels were constituted according to hemoglobin concentrations and they were divided into five groups: Gro-up I: 0-0.10 g/L, Group II: 0.10-0.50 g/L, Group III: 0.51-1.00 g/L, Group IV: 1.01-2.50 g/L, Group V: 2.51-4.50 g/L. Lysis was achieved by mechanical trauma. Results: Hemolysis interference affected lactate dehydrogenase (LD) and aspartate aminotransfera-se (AST) almost at undetectable hemolysis by visual inspection (plasma hemoglobin 1 g/L). Alanine aminotransferase (ALT), cholesterol, gamma glutamyltransferase (GGT), and inorganic phosphate (P) concentrations were not interfered up to severely hemolyzed levels (hemoglobin: 2.5-4.5 g/L). Albumin, alkaline phosphatase (ALP), amylase, chloride, HDL-cholesterol, creatine kinase (CK), glucose, magnesium, total protein, triglycerides, un-saturated iron binding capacity (UIBC) and uric acid differences were statistically significant, but re-mained within the CLIA limits. Conclusion: To avoid preanalytical visual inspection for hemolysis detection, improper sample rejec-tion, and/or rerun because of hemolysis, it is recommended in this study that, routine determination of plasma or serum free hemoglobin concentrations is important. For the analytes interfered with hemolysis, new samples have to be requested

Clinical biochemistry laboratory rejection rates due to various types of preanalytical errors

Introduction: Preanalytical errors, along the process from the beginning of test requests to the admissions of the specimens to the laboratory, cause the rejection of samples. The aim of this study was to better explain the reasons of rejected samples, regarding to their rates in certain test groups in our laboratory. Materials and methods: This preliminary study was designed on the rejected samples in one-year period, based on the rates and types of inappropriateness. Test requests and blood samples of clinical chemistry, immunoassay, hematology, glycated hemoglobin, coagulation and erythrocyte sedimentation rate test units were evaluated. Types of inappropriateness were evaluated as follows: improperly labelled samples, hemolysed, clotted specimen, insufficient volume of specimen and total request errors. Results: A total of 5,183,582 test requests from 1,035,743 blood collection tubes were considered. The total rejection rate was 0.65 %. The rejection rate of coagulation group was significantly higher (2.28%) than the other test groups (P < 0.001) including insufficient volume of specimen error rate as 1.38%. Rejection rates of hemolysis, clotted specimen and insufficient volume of sample error were found to be 8%, 24% and 34%, respectively. Total request errors, particularly, for unintelligible requests were 32% of the total for inpatients. Conclusions: The errors were especially attributable to unintelligible requests of inappropriate test requests, improperly labelled samples for inpatients and blood drawing errors especially due to insufficient volume of specimens in a coagulation test group. Further studies should be performed after corrective and preventive actions to detect a possible decrease in rejecting sample

Antinuclear antibody testing in a Turkish pediatrics clinic: is it always necessary?

Introduction:&nbsp;the term anti-nuclear antibody (ANA) is used to define a large group of autoantibodies which specifically bind to nuclear elements. Although healthy individuals may also have ANA positivity, the measurement of ANA is generally used in the diagnosis of autoimmune disorders. However, various studies have shown that ANA testing may be overused, especially in pediatrics clinics. Our aim was to investigate the reasons for antinuclear antibody (ANA) testing in the general pediatrics and pediatric rheumatology clinics of our hospital and to determine whether ANA testing was ordered appropriately by evaluating chief complaints and the ultimate diagnoses of these cases. Methods:&nbsp;the medical records of pediatric patients in whom ANA testing was performed between January 2014 and June 2016 were retrospectively evaluated. Subjects were grouped according to the indication for ANA testing and ANA titers. Results:&nbsp;ANA tests were ordered in a total of 409 patients during the study period, with 113 positive ANA results. The ANA test was ordered mostly due to joint pain (50% of the study population). There was an increased likelihood of autoimmune rheumatic diseases (ARDs) with higher ANA titer. The positive predictive value of an ANA test was 16% for any connective tissue disease and 13% for lupus in the pediatric setting. Conclusion:&nbsp;in the current study, more than one-fourth of the subjects were found to have ANA positivity, while only 15% were ultimately diagnosed with ARDs. Our findings underline the importance of an increased awareness of correct indications for ANA testing

Evaluation of nutritional status in pediatric intensive care unit patients: the results of a multicenter, prospective study in Turkey

IntroductionMalnutrition is defined as a pathological condition arising from deficient or imbalanced intake of nutritional elements. Factors such as increasing metabolic demands during the disease course in the hospitalized patients and inadequate calorie intake increase the risk of malnutrition. The aim of the present study is to evaluate nutritional status of patients admitted to pediatric intensive care units (PICU) in Turkey, examine the effect of nutrition on the treatment process and draw attention to the need for regulating nutritional support of patients while continuing existing therapies.Material and MethodIn this prospective multicenter study, the data was collected over a period of one month from PICUs participating in the PICU Nutrition Study Group in Turkey. Anthropometric data of the patients, calorie intake, 90-day mortality, need for mechanical ventilation, length of hospital stay and length of stay in intensive care unit were recorded and the relationship between these parameters was examined.ResultsOf the 614 patients included in the study, malnutrition was detected in 45.4% of the patients. Enteral feeding was initiated in 40.6% (n = 249) of the patients at day one upon admission to the intensive care unit. In the first 48 h, 86.82% (n = 533) of the patients achieved the target calorie intake, and 81.65% (n = 307) of the 376 patients remaining in the intensive care unit achieved the target calorie intake at the end of one week. The risk of mortality decreased with increasing upper mid-arm circumference and triceps skin fold thickness Z-score (OR = 0.871/0.894; p = 0.027/0.024). The risk of mortality was 2.723 times higher in patients who did not achieve the target calorie intake at first 48 h (p = 0.006) and the risk was 3.829 times higher in patients who did not achieve the target calorie intake at the end of one week (p = 0.001). The risk of mortality decreased with increasing triceps skin fold thickness Z-score (OR = 0.894; p = 0.024).ConclusionTimely and appropriate nutritional support in critically ill patients favorably affects the clinical course. The results of the present study suggest that mortality rate is higher in patients who fail to achieve the target calorie intake at first 48 h and day seven of admission to the intensive care unit. The risk of mortality decreases with increasing triceps skin fold thickness Z-score

The anti-inflammatory and antioxidant effects of pravastatin and nebivolol in rat aorta

Objective: The aim of this study was to investigate the effects of pravastatin and nebivolol in the atherosclerotic process including inflammation and oxidative stress in rat aorta

The anti-inflammatory and antioxidant effects of pravastatin and nebivolol in rat aorta

Objective: The aim of this study was to investigate the effects of pravastatin and nebivolol in the atherosclerotic process including inflammation and oxidative stress in rat aorta

Evaluation of Postprandial Total Antioxidant Activity in Normal and Overweight Individuals

WOS: 000396415800012Aim: Postprandial changes acutely alter some mechanisms in body. There are many studies showing blood oxidative status changes after food intake and supplementation. The aim of the present study was to evaluate the effects of a standardized meal on serum total antioxidant activity (TAA) in normal weight and overweight individuals. Material and Method: Fourteen normal weight and twelve overweight individuals were given a standardized meal in the morning after an overnight fast. Serum TAA, glucose, total cholesterol, HDL cholesterol, LDL cholesterol and triglyceride concentrations were measured at baseline, 3rd hour and 6th hour after the meal in both groups. Results: In both normal and overweight groups, the difference between baseline and 3rd hour was significant for TAA. The TAA of the overweight group was also significantly lower than the TAA of the normal weight group at 3rd hour. However, there was no significant correlation between lipid parameters and TAA levels. Discussion: The present study shows that postprandial oxidative stress occurs more prominently in overweight individuals than in normal weight individuals. Postprandial changes acutely induce oxidative stress and impair the natural antioxidant defense mechanism. It should be noted that consuming foods with antioxidants in order to avoid various diseases and complications is useful, particularly in obese subjects

The Acute Effects of Postprandial Hypertriglyceridemia on Coagulation Parameters in Normal and Overweight Individuals

WOS: 000217526200008Postprandial hypertriglyceridemia may have a procoagulant effect and cause an activation of coagulation system. The measurement of postprandial triglyceride concentrations and coagulation parameters may give additional useful data besides the fasting measurement. Thus, we investigated the acute effects of hypertriglyceridemia after the meal in normal and overweight individuals. Fourteen overweight (Group I) and sixteen normal weight (Group II) voluntary participants were given fat-rich meal (700 kcal). Blood samples were obtained at fasting, 3rd and 6th hours. In both groups, total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, triglyceride (TG), fibrinogen, prothrombin time (PT), activated partial thromboplastin time, factor VII (FVII), factor IX (FIX), protein C and, protein S activities were measured. As might be expected, TG levels were higher in the postprandial state than the fasting state in both groups and also Group I subjects had higher levels rather than Group II at all states. One of our important finding finding was that PT levels were shorter in Group I at the fasting, postprandial 3rd and 6th hours than Group II (P = 0.007, P = 0.033, P = 0.047 respectively). Moreover, FVII and FIX activities were found as higher in Group I at the postprandial 3rd hour (P = 0.047, P = 0.008 respectively). In conclusion, the high activities of FVII and FIX and short PT levels may predispose to thrombosis in Group I, especially at postprandial states