Establishment of the Separate Cutoff Values of 17-alpha-hydroxyprogesterone in Neonatal Screening Program for Congenital Adrenal Hyperplasia according to Birth Weight / 임상검사와정도관리

BACKGROUND: In Korea, 17-alpha-hydroxyprogesterone (17-OHP) neonatal screening for congenital adrenal hyperplasia (CAH) has a high false positive rate. Preterm infants have higher levels of 17-OHP than term infants. We established the separate cutoff values of 17-OHP under the guideline of the Clinical and Laboratory Standard Institute C28-A3 to reduce a false positive rate. METHODS: The 17-OHP enzyme-immunoassay was used in blood spots of 22,601 newborns. To decide whether to partition cutoff values based on sex, sampling date and birth weight was assessed by Z-test and standard deviation (SD) ratio. If the result was significant, we estimated the cutoff value with 90% confidence intervals (CIs) using the nonparametric method. RESULTS: In the subclasses based on sex and sampling date, the results were not significant. However, the birth weight-adjusted subclasses (SD ratio > 1.5) showed that it was necessary to distinguish low-birth-weight infants from the others. We selected the subclass categories to reflect the concept of low- or very-low-birth-weight infant. The maximum percentile to define a 90% CI was chosen in each subclass. After applied the re-estimated cutoff value, the recall rate was decreased from 0.6% to less than 0.2%. CONCLUSIONS: The birth weight-adjusted cutoff value of 17-OHP in neonatal screening for CAH can be reduced the false positive rate of low-birth-weight infants. This approach would decrease unnecessary blood draws, medical evaluation, parental anxiety and burden on health care resources.

An Epidemiological Analysis of Hepatitis A Virus Serologic Markers during the Recent Four Years in Korea / 대한진단검사의학회지

BACKGROUND: To establish effective preventive measures for hepatitis A virus (HAV) infection, a nationwide epidemiologic study on seroprevalence of anti-HAV and the disease prevalence is needed. The aim of this study was to analyze the recent sero-epidemiological changes of hepatitis A markers in Korea. METHODS: The results of 11,068 anti-HAV total and 32,360 anti-HAV IgM tests by electro-chemiluminescence immunoassay (ECLIA) that had been requested in recent four years (2005-2008) to a reference medical laboratory from 1,699 institutions nationwide were retrospectively analyzed according to the distribution of year, sex, and age groups. RESULTS: The overall positive rate of anti-HAV total was 62.8%. The overall positive rate of anti-HAV IgM was 11.0%, showing a significantly increasing trend by year: 7.7%, 10.9%, 8.9%, and 14.3% in 2005, 2006, 2007, and 2008, respectively (P or =21 yr. Conclusion: In accordance with a decreasing sero-positivity of anti-HAV total, the prevalence of acute hepatitis A virus infection has been considerably increased during the recent four years in the age groups of > or =21 yr. The results of this study could be used effectively as a basic data for establishing effective preventive measures for hepatitis A including vaccination in these susceptible age groups.

Concentrations of Blood Vitamin A, C, E, Coenzyme Q10 and Urine Cotinine Related to Cigarette Smoking Exposure / 대한진단검사의학회지

BACKGROUND: In smokers, smoking causes many disease entities including cancers, chronic pulmonary diseases and cardiovascular diseases. Passive smoking is also accepted as a carcinogen and its adverse health effects are emphasized. We measured blood vitamin A, C, E (alpha-, beta- and gamma-tocopherol), coenzyme Q10 and urine cotinine concentrations in nonsmokers and smokers. METHODS: Twenty-one healthy nonsmokers and 24 healthy smokers were included in this study. Smoking status was assessed with a self-reported questionnaire. Plasma was analyzed for coenzyme Q10 and serum for vitamin A, C, E using HPLC (Agilent Technologies Inc., USA) and random urine for cotinine using LC/tandem mass spectrometry (Applied Biosystems Inc., Canada). RESULTS: Smokers had significantly lower serum concentrations of vitamin C than nonsmokers (P=0.0005). No significant differences in concentrations of serum vitamin A, E, and plasma coenzyme Q10 were observed. Smokers had highly elevated urine cotinine levels (1,454+/-903 ng/mL). In 16 (76.2%) of 21 nonsmokers, urine cotinine was detected (3.25+/-4.08 ng/mL). The correlations between urine cotinine and blood antioxidants levels were not found. Neither, the correlation between smoking status and blood antioxidants & urine cotinine was found. CONCLUSIONS: This study shows that smokers had significantly lower vitamin C levels among nonenzymatic antioxidants, namely, vitamin A, C, E and coenzyme Q10. High detection rate of urine cotinine in nonsmokers show the seriousness of passive smoking exposure, therefore more social efforts should be directed to reduce passive smoking exposure.

Seven-year experience with inherited metabolic disorders screening by tandem mass spectrometry

PURPOSE: In recent years, many countries have adopted newborn screening programs that use tandem mass spectrometry (MS/MS) to screen and the number of diseases screened has also increased. We began screening for inherited metabolic disorders using MS/MS in April, 2001. Our goal was to determine the overall prevalence of metabolic disorders and to assess the effectiveness of newborn screening by MS/MS in Korea. METHODS: From April, 2001 to December, 2007, we screened newborns and high risk groups using MS/MS. Acylcarnitines and amino acids were extracted and butylated and were introduced into the inlet of MS/MS. Confirmatory testing including a repeat newborn screening, and urine organic acid and plasma amino acid analysis were performed on a case-by-case basis. RESULTS: The total number of screened subjects 284,933 which comprised 251,799 neonates and 33,134 high risk subjects. The recall rate was 0.4% (1158 tests) and true positive cases were 117 (0.04%). Confirmed metabolic disorders (newborn/high risk group) were as follows; 78 (25/53) amino acid disorders, 27 (16/11) organic acid disorders, and 12 (5/7) fatty acid oxidation disorders. The estimated prevalence of inherited metabolic diseases in newborns was 1:5,000 and that in the total group was 1:2,000. CONCLUSION: Newborn screening by MS/MS improved the detection of many inherited metabolic disorders. We therefore propose that all newborns be screened by a MS/MS national program and followed-up using a systemic organization strategy.

Annual Report on External Quality Assessment in Therapeutic Drug Monitoring and Drug of Abuse in Korea (2007) / 임상검사와정도관리

Two trials of external quality assessment for Therapeutic Drug Monitoring (TDM) subcommittee of Korean Association of Quality Assurance for Clinical Laboratory (KAQACL) were performed in 2007. Number of participating laboratories were increased to 109, by 5.63% increase comparing with the previous year. Response rates reached 98.7% for both trials slightly lower than that of the previous year. Two kinds of control materials were requested to be tested in each trial so that each institution could know the possible systematic error. In both trials, 20 test items were responded at least from one laboratory. The average drug item was 6.3 per institution, which was decreased slightly from 6.8 in recent 5 years. The most common test items were valproic acid, digoxin, carbamazepine, theophylline, phenytoin, and phenobarbital which were peformed in more than 55% of the participating laboratories, followed by cyclosporine, vancomycin, lithium, tacrolimus, methotrexate, amikacin, gentamicin, salicylate, tobramycin, acetaminophen, primidone, free phenytoin, and amitryptyline. The inter-laboratory coefficients of variations showed simliar tendency comparing with those of the previous years. We started the proficiency test for drug of abuse from 2007 and got the response from 13 and 17 laboratories in the 1st and 2nd trial, respectively. Average drug items were 3.4 for the 2nd trial. We found the relatively good performances as we got the correct answers from all laboratories except 4 for each one mistake. In conclusion, the TDM external quality assessment of 2007 showed grossly similar pattern comparing with those of previous year and drug of abuse proficiency testing showed a relatively good performance.

Annual Report on External Quality Assessment in Therapeutic Drug Monitoring and Drug of Abuse in Korea (2007) / 임상검사와정도관리

Two trials of external quality assessment for Therapeutic Drug Monitoring (TDM) subcommittee of Korean Association of Quality Assurance for Clinical Laboratory (KAQACL) were performed in 2007. Number of participating laboratories were increased to 109, by 5.63% increase comparing with the previous year. Response rates reached 98.7% for both trials slightly lower than that of the previous year. Two kinds of control materials were requested to be tested in each trial so that each institution could know the possible systematic error. In both trials, 20 test items were responded at least from one laboratory. The average drug item was 6.3 per institution, which was decreased slightly from 6.8 in recent 5 years. The most common test items were valproic acid, digoxin, carbamazepine, theophylline, phenytoin, and phenobarbital which were peformed in more than 55% of the participating laboratories, followed by cyclosporine, vancomycin, lithium, tacrolimus, methotrexate, amikacin, gentamicin, salicylate, tobramycin, acetaminophen, primidone, free phenytoin, and amitryptyline. The inter-laboratory coefficients of variations showed simliar tendency comparing with those of the previous years. We started the proficiency test for drug of abuse from 2007 and got the response from 13 and 17 laboratories in the 1st and 2nd trial, respectively. Average drug items were 3.4 for the 2nd trial. We found the relatively good performances as we got the correct answers from all laboratories except 4 for each one mistake. In conclusion, the TDM external quality assessment of 2007 showed grossly similar pattern comparing with those of previous year and drug of abuse proficiency testing showed a relatively good performance.

Evaluation of Normal Phase High-Performance Liquid Chromatography for Analysis of Tocopherols / 대한진단검사의학회지

BACKGROUND: Recently the tocopherol, which has been proven as an antioxidant, has also been found to possess non-antioxidant roles such as anti-inflammatory and chemopreventive effects, which has heightened the importance of rapid, accurate and reliable testing methods. We evaluated the performance of normal phase high-pressure liquid chromatography (NP-HPLC) for analysis of tocopherol in serum. METHODS: The chromatographic separation parameters, linearity, precision, accuracy and detection limit were evaluated. The analytical column was hypersil silica (4.6 mm*200 mm*5 micrometer, Thermo Electron Corporation, Keystone, PA, USA) and mobile phase comprised 2% (v/v) of isopropanol in n-hexane. Analyses were run at a flow rate of 0.7 mL/min at 295 nm. RESULTS: The run time of separation of tocopherol was completed in less than 15 minutes and its retention factor (0.61-2.13) and resolution including positional isomers ( beta- and gamma-tocopherol) were excellent. Their linearity was good (r>0.999). The coefficient of variation (CV) at medium and high concentrations did not exceed 15% and those at low concentrations did not exceed 20%. The range of its recovery was 91.4-107.8% and bias was within 15%. The detection limits of alpha-, beta-, gamma- and delta-tocopherol were 0.038, 0.064, 0.078 and 0.049, respectively. CONCLUSIONS: NP-HPLC provided a rapid, accurate and reliable performance for the separation of tocopherol and would be helpful as a routine method in the clinical laboratory.

Performance Analysis of the Beckman Coulter GEN-S Automated Hematology Analyzer / 대한임상병리학회지

BACKGROUND: The complete blood cell count (CBC) and leukocyte differential counts are useful tools for making a diagnosis, treating and monitoring a disease. This study evaluated the perfor-mance of Beckman-Coulter's new model, the Coulter GEN-S system (Beckman Coulter Corpora-tion, Miami, USA; GEN-S), and compared it with the Sysmex NE-8000 (Sysmex Corporation, Kobe, Japan; NE-8000) and Sysmex R-3000 (Sysmex Corporation, Kobe, Japan; R-3000). METHODS: One hundred and four blood samples and 120 blood samples were randomly chosen for a comparison analysis from various in-patients and healthy persons, who visited Samsung med-ical center, respectively. The GEN-S system was evaluated according to the linearity and how well it compared with the NE-8000 in terms of the CBC, and the efficiency of the leukocyte suspect flags. RESULTS: The GEN-S showed that the determination coefficients (R(2)) of the WBC, RBC, platelet count and hemoglobin level were more than 0.94 (P 0.95 (P < 0.001) when compared with the NE-8000. In addition, the correlations of the leukocyte differential counts for neutrophils, eosinophils, and lymphocytes were good, but those for monocytes and basophils were poor. The sensitivity, specificity and positive predictive value of the leukocyte suspect flags of the GEN-S system were 89%, 73%, and 43%, respectively. CONCLUSIONS: These results demonstrate the comparable performance of the GEN-S system in clinical laboratories. However, a separate microscopic differential count is required due to the low positive predictive value for the leukocyte suspect flags.

Evaluation of Serologic Marker Tests for Hepatitis B Viral Infection Using the Automated Immunoassay System ARCHITECT i2000 / 대한임상병리학회지

BACKGROUND: The prevalence of Hepatitis B virus (HBV) in Korea is still higher than that of devel-oped countries. Recently, the automated chemiluminescent microparticle immunoassay analyzer ARCHITECT i2000 (Abbott Laboratories, Abbott Park, IL USA) was introduced in Korea and we evaluated performance of the tests for serological markers for HBV infection. METHODS: We analyzed precision, agreement, sensitivity, specificity and throughput of the HBs antigen, anti-HBs and anti-HBc as well as linearity and compared with the AxSYM (Abbott Labora-tories, Abbott Park, IL USA) for anti-HBs. Precision, linearity and comparison were performed on the basis of the National Committee for Clinical Laboratory Standards guidelines. Random patients 'sera were used for this study. RESULTS: The coefficients of variations of precision were below 5% for anti-HBs and anti-HBc (total) except for the HBs antigen. The agreements, sensitivities and specificities for serologic mark-ers were more than 90%. The linearity and comparison for anti-HBs were statistically significant (P < 0.001). The throughput of ARCHITECT i2000 was 110 tests/hours and that was 2.8 times faster than that of the AxSYM. CONCLUSIONS: These results suggest that ARCHITECT i2000 can provide rapid and effective results for serologic markers for HBV infection. However, each laboratory should decide the utiliza-tion of this analyzer on the basis of volume of samples, other items tested concurrently, and the inter-face of existing facilities etc.

Therapeutic Plasma Exchanges in Patients with Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndrome / 대한임상병리학회지

BACKGROUND: Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) is a disease entity defined by the presence of thrombocytopenia and microangiopathic hemolytic anemia with or without fever, neurologic and renal symptoms. Therapeutic plasma exchange (TPE) has proven to be an effective treatment for TTP/HUS and has decreased mortality. We evaluated the effectiveness of TPE for TTP/HUS at the Department of Clinical Pathology, Samsung Medical Center during the last 6 years. METHODS: We assessed retrospectively the chief complaints, the clinical course, the treatment and the outcome in 17 TTP/HUS patients treated with TPE from December 1994 to May 2001. Minimal diagnostic criteria for TTP/HUS were unexplained thrombocytopenia and microangiopathic hemolytic anemia, with or without fever, neurologic, and renal symptoms. The range of ages of the patients was 15 to 63 years and the female to male ratio was 2:1. RESULTS: The most frequent clinical presentation was a renal problem (71%), followed by fever (53%) and neurologic symptoms (24%). The causes of TTP/HUS followed in the order of frequency: idiopathic (41%), suspicious for Escherichia coli O157: H7 infection (24%), systemic lupus erythematosus (18%), mitomycin C induced (12%), and preeclampsia (6%). A total of 229 TPE procedures were performed for 17 patients (mean: 13 procedures). The replacement fluids for TPE were fresh frozen plasma (59%) and cryosupernatant (41%). Thirteen patients (76%) survived and three of them relapsed (23%); however, they responded to further treatment. In comparing the laboratory results between pre and post TPE, significant changes were found in the white blood cells and platelet counts, creatinine, total bilirubin, and lactic dehydrogenase. The initial symptoms did not indicate a recurrence rate and a variety of drugs were used, except for corticosteroid administration. CONCLUSIONS: TTP/HUS patients responded well to TPE. The overall efficacy of TPE for TTP/HUS was 76%. The causes of TTP/HUS, the administered drugs and the replacement fluid did not affect the patient's prognosis.

Performance Analysis of Panel Reactive Antibody Test by Lambda Antigen Tray Kit using Enzyme-Linked Immunosorbent Assay / 대한임상병리학회지

BACKGROUND: To detect human leukocyte antigen(HLA) alloantibodies, panel reactive antibody(PRA) test using complement dependent lymphocytotoxicity(CDC) has been generally used in Korea but this method lacks standardization. We analyzed the performance of Lambda Antigen Tray(LAT, One Lambda, Inc., Canoga Park, USA) kit using Enzyme-linked immunosorbent assay(ELISA). METHODS: We carried out PRA screening by ELISA with LAT10X5 kit and CDC with home-made panels for 81 sera patients. We carried out PRA identification by ELISA with LAT1240 kit for some sera with positive or discordant results of both CDC and PRA screening by ELISA. RESULTS: The agreement of CDC and PRA screening by ELISA was 85%(69/81). In 12 sera with positive results of both CDC and PRA screening by ELISA, no sera had same results of HLA antibody specificities. HLA class II antibodies were found in 13 sera(16%) and 12 sera of those had HLA class I antibodies, too. CONCLUSIONS: The agreement of CDC and PRA screening by ELISA was similar to other foreign result. Disagreement of both methods might be due to greatly difference of frequencies of HLA in used panels. New manufactured goods considered frequencies of Korean HLA should be made in order that PRA by ELISA can be applied to routine work.

Antimicrobial Susceptibility of Beta-Lactam Antibiotics on Enterococcus / 대한임상미생물학회지

BACKGROUND: Enterococci exhibit intrinsic resistance or high-level minimum inhibitory concentration (MIC) to beta-lactams than other streptococci. This appears to be due to low affinity of penicillin-binding proteins and rarely production of beta-lactamase, which gives the reason of testing beta-lactamase for blood and cerebrospinal fluid isolates. Ampicillin is more effective than penicillin in vitro, and MIC of ampicillin is generally 1 dilution lower than that of penicillin. The purpose of this study is to detect beta-lactamase producing enterococci an6 to compare MICs of ampicillin and penicillin by Vitek system (bioMerieux, Hazelwood, MO, USA) with those by agar dilution method. METHODS: We collected 110 isolates of Enterococcus faecalis and 51 isolates of E. faecium from clinical specimens in 1998. MICs of antibiotics were determined by agar dilution method and Vitek system. We also performed beta-lactamase test by the Cefinase (Becton Dickinson, USA) for 512 isolates of E. faecalis and 189 isolates of E. faecium collected in 1998. RESULTS: The most common sites of isolates were blood, bile, surgical/traumatic wounds, closed and open pus and urine. MICs of ampicillin were 1 to 2 dilution lower than those of penicillin for E. faecalis (P=0.03). But there were no significant differences in MICs for E. faecium (P=0.19). Five isolates (4 E. faecalis and 1 E. faecium) were susceptible to ampicillin but resistant to penicillin. There were no beta-lactamase producing enterococci among 701 isolates tested. CONCLUSIONS: MIC by Vitek system tends to be 1 to 2 dilution lower than MIC by agar dilution method to beta-lactams, and MIC of ampicillin is 1 to 2 dilution lower than MIC of penicillin, which could result in discrepancy in interpretation of susceptibilty tests. A beta-lactamase test for enterococci is not recommeneded for routine test in Korea.