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.

In tro duc tion: He mo lysis is sti ll the mo st com mon rea son for re jec ti ng sam ples, whi le reob tai ni ng a new sam ple is an im por ta nt prob lem. The aim of this stu dy was to in ves ti ga te the eff ec ts of he mo lysis in diff e re nt he mo lysis le ve ls for mos tly used bioc he mi cal pa ra me te rs to pre ve nt un ne ces sa ry re jec tio ns. Ma te ria ls and met ho ds: Sixteen heal thy vo lun tee rs we re en rol led in the stu dy. Four he mo lysis le ve ls we re con sti tu ted ac cor di ng to he mog lo bin con cen tra tio ns and they we re di vi ded in to fi ve grou ps: Group 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 ac hie ved by mec ha ni cal trau ma. Re sul ts: Hemo lysis in ter fe ren ce aff ec ted lac ta te de hydro ge na se (LD) and as par ta te ami not ran sfe ra se (AST) al mo st at un de tec tab le he mo lysis by vi sual in spec tion (plas ma he mog lo bin < 0.5 g/L). Cli ni cal ly mea nin gful va ria tio ns of po tas sium and to tal bi li ru bin were ob ser ved in mo de ra te ly hemo lyzed sam ples (he mog lo bin > 1 g/L). Ala ni ne ami not ran sfe ra se (ALT), cho les te rol, gam ma glu ta myltran sfe ra se (GGT), and inor ga nic phos pha te (P) con cen tra tio ns we re not in ter fe red up to se ve re ly he mo lyzed le ve ls (he mog lo bin: 2.5-4.5 g/L). Albu min, al ka li ne phos pha ta se (ALP), amyla se, chlo ri de, HDL-cho les te rol, crea ti ne ki na se (CK), glu co se, mag ne sium, to tal pro tein, trig lyce ri des, un sa tu ra ted iron bin di ng ca pa ci ty (UIBC) and uric acid diff e ren ces we re sta tis ti cal ly sig ni fi ca nt, but re mai ned wit hin the CLIA li mi ts. Con clu sion: To avoid prea na lyti cal vi sual in spec tion for he mo lysis de tec tion, im pro per sam ple re jec tion, and/or re run be cau se of he mo lysis, it is recom men ded in this stu dy that, rou ti ne deter mi na tion of plas ma or se rum free he mog lo bin con cen tra tio ns is important. For the ana lytes in ter fe red wi th he mo lysis, new sam ples ha ve to be reques ted. Key wor ds: he mo lysis; prea na lyti cal er ro rs; in ter fe ren ce; ana lytes.

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 samples.

IntroductionThe collected and shipped blood samples are exposed to a various extra-analytical factors prior to analysis. The aim of the study was to determine the stability of analytes in serum gel tubes and plain tubes exposed to a range of storage temperatures and times after centrifugation.Materials and methods:Fifteen healthy volunteers were recruited and venous blood was collected into four tubes, two with and two without gel separator. Analyzing the baseline samples in 30 min, all were stored at 4ºC or 24ºC for 6, 12, 18, 24, 30, 36, 48 and 72 hours and 1 week. Sixteen biochemical anaytes were measured on each sample. Variations remained under the desirable bias considered as clinically insignificant.Results:On day three, most analytes remained stable including albumin, protein, creatinine, cholesterol, triglycerides, gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), alanine aminotransferase (ALT), creatine kinase (CK), lactate dehydrogenase (LD) regardless of tube types. Glucose concentration decreased markedly (P = 0.001) beginning from the first hours of storage in plain serum. The stability maximized for the analytes including glucose, total bilirubin, urea nitrogen (BUN), uric acid stored at 4 ºC in gel tubes. Aspartate aminotransferase (AST) activity increased significantly (P = 0.002) up to 48-h, however bias was not significant clinically. High density lipoprotein (HDL) concentration was stable in gel tubes at 24 ºC, in plain tubes at 4 ºC stored up to 36-h.Conclusion:Serum gel or non-gel tubes might be used interchangeably for 11 analytes chilled or at 24 ºC, whereas some restrictions must be applied for glucose, AST, BUN, HDL, and uric acid.

Background: Breast cancer is the second leading cancer causing death in women. Circulating tumor cells are among the prognostic factors while tumor markers are of diagnostic value and can be used for follow-up. The aim of this study was to investigate the correlation between the prognostic significance of the serum CA15-3 levels, number of circulating tumor cells and histopathological tumor factors. Materials and Methods: Thirty patients recently diagnosed with breast cancer were included in the study. Number of circulating tumor cells and serum CA15-3 level were assessed when metastasis was detected and diagnostic value was assessed. Presence of associations with estrogen and progesterone receptors, c-erbB2, Ki-67 proliferation index and histological grade were also evaluated. Results: Median overall survival of the patients with serum CA15-3 levels of >108 ng/dl was 19 months whereas for those with a low serum level it was 62 months. Median overall survival for CTC ≥5vs CTC<5 patients was 19 months and 40 months respectively. The difference between the two groups was statistically significant. Conclusions: Prognostic significance of the CTC count and CA15-3 levels in metastatic breast cancer patients was demonstrated.