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1.
Sigma is a metric that quantifies the performance of a process as a rate of Defects-Per-Million opportunities. In clinical laboratories, sigma metric analysis is used to assess the performance of laboratory process system. Sigma metric is also used as a quality management strategy for a laboratory process to improve the quality by addressing the errors after identification. The aim of this study is to evaluate the errors in quality control of analytical phase of laboratory system by sigma metric. For this purpose sigma metric analysis was done for analytes using the internal and external quality control as quality indicators. Results of sigma metric analysis were used to identify the gaps and need for modification in the strategy of laboratory quality control procedure. Sigma metric was calculated for quality control program of ten clinical chemistry analytes including glucose, chloride, cholesterol, triglyceride, HDL, albumin, direct bilirubin, total bilirubin, protein and creatinine, at two control levels. To calculate the sigma metric imprecision and bias was calculated with internal and external quality control data, respectively. The minimum acceptable performance was considered as 3 sigma. Westgard sigma rules were applied to customize the quality control procedure. Sigma level was found acceptable (≥3) for glucose (L2), cholesterol, triglyceride, HDL, direct bilirubin and creatinine at both levels of control. For rest of the analytes sigma metric was found <3. The lowest value for sigma was found for chloride (1.1) at L2. The highest value of sigma was found for creatinine (10.1) at L3. HDL was found with the highest sigma values at both control levels (8.8 and 8.0 at L2 and L3, respectively). We conclude that analytes with the sigma value <3 are required strict monitoring and modification in quality control procedure. In this study application of sigma rules provided us the practical solution for improved and focused design of QC procedure.  相似文献   

2.
This paper presents certain simple procedures for assessing the most common types of interference, due to haemolysis, icterus or lipaemic serum in 19 routine Clinical Chemistry tests and suggests steps to overcome the problem in some tests. A change in the measured concentration, to be analytically significant, had to exceed 2.8 X % coefficient of variation (cv) of the intra-assay analytical variation of each assay. Haemolysis caused interference in 10 of the 19 assays investigated. A haemolysate haemoglobin concentration of 0.29 g/dl, visible to the eye, caused an analytically significant increase in creatinine kinase MB subunit (CKMB), lactate dehydrogenase (LDH), total protein, triglyceride, uric acid and urea, and a significant decrease in alkaline phosphatase (ALP), and total bilirubin. A higher concentration of haemoglobin (0.68 g/ dl) caused an additional significant increase in CK, and a decrease in direct bilirubin. Addition of bilirubin caused interference in all the peroxidase linked reactions as well as in the creatinine assay. At a serum concentration of 5.2 mg/dl it caused a decrease in creatinine, glucose, triglyceride and uric acid. At a higher concentration (15.9 mg/dl) it also decreased cholesterol. Lipaemia interference affected the least number of assays. An added triglyceride of 537–561 mg/dl caused an increase in glucose, uric acid, and amylase. At a level of 1122 mg/dl it also increased CKMB, and at a value of 2244 mg/dl it increased total and direct bilirubin. At the highest levels of haemolysis and lipaemia, the serum glutamate oxaloacetate transaminase (GOT) and giutamate pyruvate transaminase (GPT) gave erratic results. Overall uric acid and CKMB were the analytes most susceptible to interference, while serum caicium and phosphate did not suffer from any. The interference depends on the exact assay conditions used and the susceptibility of each individual laboratory's tests should be determined by them. The reasons for the interferences described are discussed.  相似文献   

3.
Quality control (QC) materials are crucial for internal quality control (IQC) and external quality assessment scheme (EQAS). However, many developing countries are disadvantaged by unavailability and high cost of commercial control material. Therefore, preparing home-made lyophilized human serum will be cost effective for used as a QC material in Bhutan. We prepared lyophilized QC material using serum collected from Bhutanese volunteers. The stability of lyophilized serum was studied at 3 selected conditions by analyzing at certain intervals. The results were statistically compared with initial values. The significant p values (<0.05) were seen in glucose, BUN, ALT, total bilirubin and protein at 2–8 °C but no significant difference were observed at −20 °C at the end of 9 months. We concluded that, home-made lyophilized human serum prepared without stabilizers could be used at least up to 9 months if stored at −20 °C and 7 months at 2–8 °C. Stabilizers and additives are necessary if the materials are to be used longer than 7–9 months.  相似文献   

4.
Total cholesterol, total bilirubin, calcium, oxalate, inorganic phosphate, magnesium, iron, copper, sodium and potassium were analyzed quantitatively in gallstones, bile of gall bladder and sera of 200 patients of cholelithiasis (52 cholesterol, 76 mixed and 72 pigment stone patients) and their contents were correlated between calculi and bile and sera and bile in these three type of stone patients. A significant positive correlation was observed between total cholesterol, total bilirubin of calculi and bile, copper of bile and sera of cholesterol stone patients, copper of calculi and bile, total bilirubin, oxalate, magnesium, potassium of sera and bile of pigment stone patients and oxalate and iron of stone and bile, total bilirubin, oxalate, sodium of sera and bile of mixed stone patients. A significant negative correlation was found between magnesium of serum and bile of cholesterol stone patients, oxalate of calculi and bile of pigment stone patients and magnesium of serum and bile of mixed stone patients.  相似文献   

5.
Chemical composition of gall stones is essential for aetiopathogensis of gallstone disease. We have reported quantitative chemical analysis of total cholesterol bilirubin, calcium, iron and inorganic phosphate in 120 gallstones from haryana. To extend this chemical analysis of gall stones by studying more cases and by analyzing more chemical constituents. A quantitative chemical analysis of total cholesterol, total bilirubin, fatty acids, triglycerides, phospholipids, bile acids, soluble proteins, sodium potassium, magnesium, copper, oxalate and chlorides of biliary calculi (52 cholesterol, 76 mixed and 72 pigment) retrieved from surgical operation of 200 patients from Haryana state was carried out. Total cholesterol as the major component and total bilirubin, phospholipids, triglycerides, bile acids, fatty acids (esterified), soluble protein, calcium, magnesium, iron, copper, sodium, potassium, inorganic phosphate, oxalate and chloride as minor components were found in all types of calculi. The cholesterol stones had higher content of total cholesterol, phospholipids, fatty acids (esterified), inorganic phosphate and copper compared to mixed and pigment stones. The mixed stones had higher content of iron and triglycerides than to cholesterol and pigment stones. The pigment stones were richer in total bilirubin, bile acids, calcium, oxalate, magnesium, sodium, potassium, chloride and soluble protein compared to cholesterol and mixed stones. Although total cholesterol was a major component of cholesterol, mixed and pigment gall stone in Haryana, the content of most of the other lipids, cations and anions was different in different gall stones indicating their different mechanism of formation.  相似文献   

6.
We have studied the expression of lactate dehydrogenase and its isoforms in gall bladder cancer, cholelithiasis and chronic cholecystitis. Quantitative and qualitative assays of lactate dehydrogenase and its various isoforms were carried out in the blood sera of patients and healthy controls along with parallel estimation of various liver function test enzymes. Statistical analysis was done using the software Graph Pad Prism. Significantly high expression of lactate dehydrogenase along with alkaline phosphatase and total bilirubin (P ≤ 0.05) was observed in all the three clinical conditions as compared to controls. LDH showed an increasing trend from stage I to stage IV of GBC indicating a significant positive association with the disease progression. The levels of LDH 3 and 4 isoforms appeared significantly more elevated in GBC than cholelithiasis or chronic cholecystitis. We suggest that a careful estimation of total LDH and its isoforms 3 and 4 alone or along with alkaline phosphatase and total bilirubin during different clinical stages, like chronic cholecystitis, cholelithiasis and GBC, may prove to be a potentially useful biomarker in the prognostic management of gall bladder diseases, specifically GBC.  相似文献   

7.

Introduction

Glycosylated hemoglobin (HbA1c) concentrations measured in clinical chemistry laboratories show large differences between their interlaboratory reported values. Laboratory measurements of quality performance should be based on quantitative data. The sigma metrics model provides an objective method for the assessment of current HbA1c assays and is useful in quality management planning. The aim of our study was to evaluate the analytical performance of the MQ-2000 PT HbA1c analyzer test results in the context of our operating conditions on the sigma scale.

Materials and methods

The coefficient of variation was determined from the calculated mean and standard deviation evaluated from internal quality control (QC) (N = 168 days) (Shanghai Huachen Biological Reagent Co. Ltd, China) data, and records of external quality data (KBUDEK, İstanbul, Turkey) measured in the period from May to November 2013 were used to determine the bias. The resulting data and total allowable error rate (TEA = 10%) from the Clinical Laboratory Improvement Amendments of 1988 (CLIA’88) were used to calculate the sigma level.

Results

The calculated coefficient of variations (CVs) at the two levels, normal (QC1 = 36.6 ± 2.38 mmol/mol) and pathological (QC2 = 84.7 ± 2.68 mmol/mol), were 6.5% and 3.1%, respectively. The average bias between the external QC and MQ-2000 PT during the study period was 4.3%. The calculated average sigma value was 1.19.

Conclusions

The MQ-2000 PT HbA1c is a new analyser in the market; there is need for improvement and the method should be controlled with greater attention to ensure quality.Key words: diabetes mellitus, hemoglobin A1c protein, human, chromatography, high pressure liquid chromatography  相似文献   

8.

Introduction:

The contamination of serum or lithium heparin blood with ethylenediaminetetraacetic acid (EDTA) salts may affect accuracy of some critical analytes and jeopardize patient safety. The aim of this study was to evaluate the effect of lithium heparin sample contamination with different amounts of K2EDTA.

Materials and methods:

Fifteen volunteers were enrolled among the laboratory staff. Two lithium heparin tubes and one K2EDTA tube were collected from each subject. The lithium-heparin tubes of each subject were pooled and divided in 5 aliquots. The whole blood of K2EDTA tube was then added in scalar amount to autologous heparinised aliquots, to obtained different degrees of K2EDTA blood volume contamination (0%; 5%; 13%; 29%; 43%). The following clinical chemistry parameters were then measured in centrifuged aliquots: alanine aminotranspherase (ALT), bilirubin (total), calcium, chloride, creatinine, iron, lactate dehydrogenase (LD), lipase, magnesium, phosphate, potassium, sodium.

Results:

A significant variation starting from 5% K2EDTA contamination was observed for calcium, chloride, iron, LD, magnesium (all decreased) and potassium (increased). The variation of phosphate and sodium (both increased) was significant after 13% and 29% K2EDTA contamination, respectively. The values of ALT, bilirubin, creatinine and lipase remained unchanged up to 43% K2EDTA contamination. When variations were compared with desirable quality specifications, the bias was significant for calcium, chloride, LD, magnesium and potassium (from 5% K2EDTA contamination), sodium, phosphate and iron (from 29% K2EDTA contamination).

Conclusions:

The concentration of calcium, magnesium, potassium, chloride and LD appears to be dramatically biased by even modest K2EDTA contamination (i.e., 5%). The values of iron, phosphate, and sodium are still reliable up to 29% K2EDTA contamination, whereas ALT, bilirubin, creatinine and lipase appear overall less vulnerable towards K2EDTA contamination.  相似文献   

9.

Introduction

The validation process is essential in accredited clinical laboratories. Aim of this study was to validate five kinds of serum vacuum tubes for routine clinical chemistry laboratory testing.

Materials and methods:

Blood specimens from 100 volunteers in five diff erent serum vacuum tubes (Tube I: VACUETTE®, Tube II: LABOR IMPORT®, Tube III: S-Monovette®, Tube IV: SST® and Tube V: SST II®) were collected by a single, expert phlebotomist. The routine clinical chemistry tests were analyzed on cobas® 6000 module. The significance of the diff erences between samples was assessed by paired Student’s t-test after checking for normality. The level of statistical significance was set at P < 0.005. Finally, the biases from Tube I, Tube II, Tube III, Tube IV and Tube V were compared with the current desirable quality specifications for bias (B), derived from biological variation.

Results and conclusions:

Basically, our validation will permit the laboratory or hospital managers to select the brand’s vacuum tubes validated according him/her technical or economical reasons, in order to perform the following laboratory tests: glucose, total cholesterol, high density lipoprotein-cholesterol, triglycerides, total protein, albumin, blood urea nitrogen, uric acid, alkaline phosphatise, aspartate aminotransferase, gamma-glutamyltransferase, lactate dehydrogenase, creatine kinase, total bilirubin, direct bilirubin, calcium, iron, sodium and potassium. On the contrary special attention will be required if the laboratory already performs creatinine, amylase, phosphate and magnesium determinations and the quality laboratory manager intend to change the serum tubes. We suggest that laboratory management should both standardize the procedures and frequently evaluate the quality of in vitro diagnostic devices.  相似文献   

10.

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.  相似文献   

11.
The negative interference of bilirubin on serum creatinine determined by the kinetic alkaline picrate (Jaffe) reaction is the unresolved problem. Though high performance liquid chromatography and gas chromatography with mass spectroscopy have been proposed to be gold standards for creatinine estimation but they are not readily available in most of the clinical chemistry laboratories due to economic and technical constraints. Most of the present day analyzers use Jaffe’s kinetic method without deproteinization. Though enzymatic methods are now routinely used as most accurate method but they are not acceptable due to cost constraints. Hence this study was planned to find out a possible solution to the problem of bilirubin interference by a minor modification in the commonly used Jaffe method so that it is amenable for use on the currently used analyzers.  相似文献   

12.
IntroductionTotal bilirubin tests are highly demanded in clinical laboratories. Since icteric index (I-index) has zero cost, we aimed to evaluate its clinical utility and cost-effectiveness to determine if total bilirubin is necessary to be tested. We took into account if haemolysis could interfere to icteric index determination.Material and methodsRetrospectively we reviewed I-index results in two cohorts (43,372 and 8507 non-haemolysed and haemolysed samples, respectively). All determinations were done using Alinity c chemistry analysers (Abbott Diagnostics). Receiver operating characteristic (ROC) curve was used to determine the optimal index cut-off to discriminate between normal and abnormal bilirubin concentration (20.5 µmol/L).ResultsThe ROC curve analysis suggested 21.4 µmol/L as the optimal I-index cut-off but differences in sensitivity and specificity were detected between patient derivation. For rejecting purpose, 15.4 µmol/L and 17.1 µmol/L I-index thresholds were selected based on patient derivation (inpatients and emergency room; and primary care and outpatients, respectively) with 97% sensitivity and 0.25% false negative results. Sensitivity was much lower in haemolysed samples. We selected 34.2 µmol/L I-index as threshold to detect hyperbilirubinemia with 99.7% specificity and 0.26% false positive results, independent of haemolysis. With the icteric index cut-offs proposed, we would save 66% of total bilirubin requested and analyse total bilirubin in around 2% of samples without total bilirubin requested.ConclusionsThis study supports the use of I-index to avoid bilirubin determination and to identify patients with hyperbilirubinemia. This work considers that the economic and test savings could help to increase the efficiency in clinical laboratories.  相似文献   

13.
The negative interference by bilirubin in serum creatinine estimation by Jaffe’s kinetic method is well known. Several approaches have been suggested to overcome this interference. In this article three different creatinine kits (Jaffe’s kinetic method) have been tested for bilirubin interference and its rectification using two simple approaches. The performance of three kits (A, B and C) supplied by three different manufacturers was tested using IQC and EQAS sera and pooled serum with added bilirubin. To overcome the bilirubin interference two approaches viz. NaOH preincubation and TCA precipitation were used. Bilirubin did interfere in creatinine estimation after a certain level (2.3 mg/dl). However, both NaOH preincubation and TCA precipitation approach rectified this interference. The performance of kit A was better than kit B and C. All the three kits showed bilirubin interference upon increasing the bilirubin concentration but kit A performed better than kit B and C. However, NaOH incubation and TCA precipitation methods overcame this interference to a great extent.  相似文献   

14.
Serum total cholesterol and triglyceride levels were estimated in 45 dilated cardiomyopathy (DCM) patients and were compared with 31 healthy controls. The total serum cholesterol (215±50 mg/dl) and serum triglyceride (162±76 mg/dl) levels in DCM patients did not show any significant changes as compared to normal controls. The cholesterol and triglyceride and the individual lipoprotein fractions, viz HDL, VLDL, LDL and chylomicrons were analysed in 10 patients. The values did not differ significantly when compared to those of controls. These findings suggest that serum lipids may not play a role in the antietiopathogenesis of DCM.  相似文献   

15.

Introduction

To investigate the state of the art of intra-laboratory turnaround time (intra-TAT), provide suggestions and find out whether laboratories accredited by International Organization for Standardization (ISO) 15189 or College of American Pathologists (CAP) will show better performance on intra-TAT than non-accredited ones.

Materials and methods

479 Chinese clinical laboratories participating in the external quality assessment programs of chemistry, blood gas, and haematology tests organized by the National Centre for Clinical Laboratories in China were included in our study. General information and the median of intra-TAT of routine and stat tests in last one week were asked in the questionnaires.

Results

The response rate of clinical biochemistry, blood gas, and haematology testing were 36% (479 / 1307), 38% (228 / 598), and 36% (449 / 1250), respectively. More than 50% of laboratories indicated that they had set up intra-TAT median goals and almost 60% of laboratories declared they had monitored intra-TAT generally for every analyte they performed. Among all analytes we investigated, the intra-TAT of haematology analytes was shorter than biochemistry while the intra-TAT of blood gas analytes was the shortest. There were significant differences between median intra-TAT on different days of the week for routine tests. However, there were no significant differences in median intra-TAT reported by accredited laboratories and non-accredited laboratories.

Conclusions

Many laboratories in China are aware of intra-TAT control and are making effort to reach the target. There is still space for improvement. Accredited laboratories have better status on intra-TAT monitoring and target setting than the non-accredited, but there are no significant differences in median intra-TAT reported by them.Key words: quality indicators, quality control, clinical laboratory services  相似文献   

16.
External Quality Assessment Scheme (EQAS) involves evaluation of a number of laboratories by an outside agency on the performance of a number of laboratories based on their analytical performance of tests on samples supplied by the external agency. In developing countries, establishment of national EQAS by preparing homemade quality control material is a useful scheme in terms of resources and time to monitor the laboratory performance. The objective of this study is to implement an EQAS to monitor the analytical performance of the district laboratories in Bhutan. Baseline information was collected through questionnaires. Lyophilized human serum including normal and abnormal levels were prepared and distributed to 19 participating laboratories. Nine routine analytes were included for the study. Their results were evaluated using Variance index scores (VIS) and Coefficient of variations (CV) was compared with Clinical Laboratory Improvement Act (CLIA) Proficiency Testing Criteria (PT) for each analyte. There was significant decrease in CV at the end of the study. The percentages of results in acceptable VIS as ‘A’ were 63, 60, 66, 69, 73 and 74, 75, 76 and 79 % in November 2009–July 2010 respectively. From our results, we concluded that, establishment of EQAS through distribution of home-made quality control material could be the useful scheme to monitor the laboratory performance in clinical chemistry in Bhutan.  相似文献   

17.
A new device called Buzzy® has been recently presented that combines a cooling ice pack and a vibrating motor in order to relieve the venipuncture pain. The aim of this study was to evaluate the impact of Buzzy® use during diagnostic blood specimen collection by venipuncture for routine immunochemistry tests. Blood was collected from 100 volunteers by a single, expert phlebotomist. A vein was located on the left forearm without applying tourniquet, in order to prevent any interference from venous stasis, and blood samples were collected using a 20-G straight needle directly into 5 mL vacuum tubes with clot activator and gel separator. In sequence, external cold and vibration by Buzzy® was applied on the right forearm—5 cm above the chosen puncture site—for 1 min before venipuncture and continued until the end of the same procedure already done in the left forearm. The panel of tests included the following: glucose, total cholesterol, HDL-cholesterol, triglycerides, total protein, albumin, c-reactive protein, urea, creatinine, uric acid, alkaline phosphatase, amylase, AST, ALT, g-glutamyltransferase, lactate dehydrogenase, creatine kinase, total bilirubin, phosphorus, calcium, magnesium, iron, sodium, potassium, chloride, lipase, cortisol, insulin, thyroid-stimulating hormone, total triiodothyronine, free triiodothyronine, total thyroxine, free thyroxine and haemolysis index. Clinically significant differences between samples were found only for: total protein, albumin and transferrin. The Buzzy® can be used during diagnostic blood specimens collection by venipuncture for the majority of the routine immunochemistry tests. We only suggest avoiding this device during blood collection when protein, albumin and transferrin determinations should be performed.  相似文献   

18.
The estimation of electrolytes like sodium (Na+), potassium (K+) and chloride (Cl−) using direct and indirect ion-selective electrodes (ISE) is a routine laboratory practice. Interferents like proteins, triglycerides, drugs etc. are known to affect the results. The present study was designed to look into the effect of increasing glucose concentrations on estimation of Na+, K+ and Cl− by direct and indirect ISE. Pooled sera was mixed with glucose stock solution (20 g/dL) prepared in normal saline to obtain glucose concentrations ranging from ~100 to ~5000 mg/dL. Na+, K+ and Cl− levels were estimated by direct and indirect ISE analyzers and results were statistically analysed using ANOVA and Pearson’s correlation. Similar experiment was also performed in 24 h urine sample from healthy subjects. Significant difference was observed between Na+ and Cl− measurements by direct and indirect ISE, with indirect ISE values being consistently higher than direct ISE. Besides this, significant difference was observed amongst Na+ and Cl− values from baseline values obtained by indirect ISE at glucose concentrations ≥2486 mg/dL. However, no such difference was observed with direct ISE. Na+ and Cl− estimation by indirect ISE showed significant negative correlation with glucose concentration, more so, above ~2000 mg/dL. K+, however, showed no significant difference with varying glucose. Similar results were observed in 24 h urine samples with a significant difference observed amongst Na+ and Cl− values at ≥2104 mg/dL glucose. Thus we conclude that high glucose concentrations interfere significantly in estimation of Na+ and Cl− by indirect ISE in serum as well as urine.

Electronic supplementary material

The online version of this article (doi:10.1007/s12291-015-0522-0) contains supplementary material, which is available to authorized users.  相似文献   

19.
An external quality assessment was conducted for RIA of thyroid related hormones. Thirtyfive laboratories (35 for T4, 34 for T3 and 23 for TSH) from different parts of country participated in the programme. Twentyfour samples (16 pools: 5 simple and 11 manipulated pools) in 8 batches, 3 per batch per month were sent for analysis of T4, T3 and TSH. Some of the samples were repeated 3 times at different occasions to assess the imprecision of the laboratory. The overall mean percent CV obtained for T4, T3 and TSH were 22.7, 36.32 and 52.38 respectively. The recovery for added T4 was 86.73% while that for T3 was 117.4%. A large variation was obtained for recovery of TSH. For T4 estimations, 13 laboratories had a desirable performance i. e. bias less than ±10.0% and variability of bias (VB) and imprecision (IP) less than 15.0%. None of the laboratories had a desirable performance for T3 or TSH. The number of laboratories with acceptable performance i. e. bias between ±10.0–15.0%, VB and IP between 20.0–25.0% for T4, T3 and TSH were 4, 3 and 0 respectively. The number of laboratories which required attention (bias between ±15.0–20.0%; VB and IP between 20.0–25.0%) were 5,7 and 1 respectively. The unacceptable results with larger bias, VB and IP for T4, T3 and TSH were 6, 18 and 17 respectively. Our results are in general agreement that the performance of T4 assay is better than T3 and both in turn are much better than TSH. Quantitation of circulating thyroid hormones (TH) viz. tri-iodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH), which form the largest percentage of hormones estimated in a clinical laboratory is mainly done by radio-immunoassay (RIA) procedures. The reliability and reproducibility of these assays are generally monitored by using internal quality control (IQC) samples in every assay batch. Thus, the IQC provides information whether the assay results are satisfactory and can be released. However, external quality assessment (EQA) is a procedure whereby an external agency undertakes evaluation of the quality of an analytical service by providing samples for analysis to individual laboratories performing the assay. The data gathered is analysed collectively. EQA therefore provides a means by which performance of a laboratory is assessed in relation to other laboratories and matching the assay unbiased by removing systematic error, if present. This is important since RIA procedure involves several steps (collection and storage of samples, quality of the reagents, procedure followed for performance of an assay, counting equipment used and the mode of the data analysis) and therefore prone to systematic errors. We therefore undertook the EQA programme for assessment of thyroid related hormones as a joint collaborative project of Bhabha Atomic Research Centre, India and International Atomic Energy Agency.  相似文献   

20.
Reactive oxygen species (ROS) formed in various metabolic reactions cause unlimited damage by attacking and oxidizing the macromolecules. An arsenal of antioxidant substances neutralizes these ROS at various sites of their metabolic cascade, and if disequilibrium exists between the pro and antioxidant system, oxidative stress persists. The present study was undertaken in schizophrenia, to highlight the response and role of some endogenous antioxidants viz. reduced glutathione (GSH), bilirubin, total proteins, albumin and uric acid in scavenging the ROS. The effect of severity of disease, age factor, and substance abuse was also studied. In all, 50 schizophrenics and 50 age and sex-matched controls were enrolled in the present study. Fasting blood samples were drawn for estimating malondialdehyde (MDA), GSH, bilirubin, total proteins, albumin and uric acid in both the groups. The results were statistically analyzed by Z-test and correlated using correlation coefficient (r). The study shows reduction in MDA levels and decline in the level of endogenous antioxidants, but within the normal range. Chronic schizophrenics were at a higher risk of oxidative stress and age and substance abuse seems to worsen the situation.  相似文献   

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