REPORT ON PROFICIENCY TESTING Report on the External Quality Assessment Scheme for Metabolite Testing in

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1 REPORT ON PROFICIENCY TESTING Report on the External Quality Assessment Scheme for Metabolite Testing in Korea ( ) Soo-Youn Lee Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea Corresponding author: Soo-Youn Lee Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea Tel: Fax: External quality assessment (EQA) trials of conventional newborn screening tests for phenylketonuria, galactosemia, congenital adrenal hyperplasia, maple syrup urine disease, homocystinuria, and congenital hypothyroidism, as well as extended newborn screening tests using tandem mass spectrometry, were performed twice in 2016 and A total of 44 specimens in the form of dried blood spots were distributed in each trial to 16 laboratories. The response rate of these laboratories was 100%. The mean, standard deviation, coefficient of variation, median, and cut-offs were evaluated for each analyte in the newborn screening tests. EQA trials for the analyses of methylmalonic acid, vanillylmandelic acid, catecholamines, metanephrines, organic acids, and amino acids were also performed. A well-designed EQA program and continuous education would improve the performance of metabolite testing. (J Lab Med Qual Assur 2018;40: ) Key Words: External quality assessment, Newborn screening, Tandem mass spectrometry, Amino acid, Organic acid, Metabolite pissn: eissn: 서론 대한임상검사정도관리협회에서는 1997년도부터선천성대사질환선별검사에대한신빙도조사사업을시작하여매년 2회의신빙도조사를시행해오고있다. 탠덤질량분석기 (tandem mass spectrometry, MS/MS) 를이용한광범위선별검사에대한신빙도조사사업은 2004년도에예비신빙도조사를실시한이래 2007년도부터정규항목으로포함하여시행중이다 [1]. 2011년도부터는예비신빙도조사를거쳐소변메틸말론산 (methylmalonic acid, MMA) 와바닐만델산 (vanillylmandelic acid, VMA), 소변유기산분석을추가하였고, 2012년도부터는혈장아미노산및유기산종목을추가하였으며, 2014년도에는요중카테콜라민 (catecholamines), 메타네프린 (metanephrines) 종목을, 2016년도부터는혈중카테콜라민및메타네프린종목까지추가하면서점차사업대상종목을확대해시행하였다 [2-6]. 이에상기검사항목들에대해 2016년및 2017년실시된총 4회의신빙도조사결과를분석 요약하여보고하고자한다. 재료및방법 1. 대상및검체 2016년도및 2017년도총 4회의대사물질검사신빙도조사대상항목및정도관리검체현황은 Table 1에정리하였다. 정도관리검체는모두자가제조검체였으며, 성분별표준물질및상품화된정도관리물질을활용하여준비하였다. 검체제조에사용된표준물질은 Sigma-Aldrich (St. Louis, MO, USA), Toronto Research Chemicals Inc. (North York, ON, Canada), International Laboratory USA (South San Francisco, CA, USA), Crystal Chem USA (Elk Grove Village, IL, USA) 등으로부터구매하였다. 또한 Bio-Rad Laboratories (Hercules, CA, USA), Simens Healthcare Diagnositcs Inc. (Tarrytown, NY, USA) 등으로부터구매한보정물질이나정도관리물질도검체제조에일부활용하였다. 136 Copyright 2018 Korean Association of External Quality Assessment Service

2 Table 1. Test items and specimens included in the proficiency tests Neonatal screening Test items Category Specimen No. of specimens Year 2016 Year st trial 2nd trial 1st trial 2nd trial Conventional Phenylketonuria DBS Expanded (by tandem mass spectrometry) Congenital hypothyroidism (thyroidstimulating hormone, thyroxine total or free) Galactosemia Congenital adrenal hyperplasia (17-hydroxyprogesterone) Maple syrup urine disease Homocystinuria Approximately 40 inherited metabolic disorders DBS Vanillylmandelic acid Urine Methylmalonic acid Urine Organic acids Approximately 70 organic acids Urine Amino acids Approximately 40 amino acids Plasma Catecholamines Dopamin, epinephrine, norepinephrine Urine Plasma Metanephrines Metanephrine, normetanephrine Urine Abbreviation: DBS, dried blood spot. Plasma 모든신빙도조사회차별로항목별정상과비정상수치가모두포함되도록하였으며, 일부검체에대해서는특정대사질환에특이적인성분다수를동시에포함시켰다. 대사산물검사를위한검체들은냉동상태로운반되었으며, 각기관에서검체를수령한즉시냉동보관하도록권고하였다. 기본선별검사의대상질환으로는페닐케톤뇨증 (phenylketonuria, PKU), 갈락토오스혈증 (galactosemia), 선천성부신과형성증 (congenital adrenal hyperplasia), 단풍당뇨증 (maple syrup urine disease, MSUD), 호모시스틴뇨증 (homocystinuria, HCY), 선천성갑상선기능저하증 (congenital hypothyroidism) 등 6가지가포함되었으며, 총 16기관을대상으로각회차별총 22개, 연도별총 44개의건조혈액여과지 (dried blood spot, DBS) 검체를발송하였다. MS/MS를이용한광범위선별검사항목으로아실카르니틴 (acylcarnitine, AC) 및아미노산 14종목과 8종의상대적비율 (ratio) 이포함되었다. DBS 정도관리검체는모두자가제조하여준비하였다. DBS 자가제조를위해 HIV항체와 B형간염항원이음성인혼합혈청에식염수로세척한 O형적혈구적 당량을첨가하여헤마토크릿을약 55% 가되도록맞춘전혈을준비한후측정대상성분에대한표준품을목표한농도로첨가하였다. 이를여과지에 75 μl 씩분주하여 DBS를만든다음실온의암실에서충분히말린후보관하였다. 아미노산, 유기산검사를위한정도관리검체는혼합혈청 ( 유기산검사를위한소변검체는정상성인의혼합소변에특정질환에서대표적으로상승하는성분에대한표준물질을고농도로첨가하여제조하였다. 혈장아미노산분석을위해서는정상성인의혼합혈장 (pooled plasma) 에특정질환에서대표적으로상승하는아미노산성분에대한표준물질 (Sigma- Aldrich, St. Louis, MO, USA) 을첨가한혈장검체를제조하여발송하였다. Pooled serum 또는혼합소변 (pooled urine) 에상품화된표준물질을첨가하여제조하였다. MMA 및 VMA 신빙도조사물질로는정상성인의혼합소변에해당표준물질을다양한농도로첨가하여각회차별로각각 3개씩제조및발송하였다. 카테콜라민과메타네프린종목신빙도조사를검체들역시환자들의혼합소변또는혈액에해당표준물질을첨가하여목표농도로제조및발송하였다. J Lab Med Qual Assur 2018;40:

3 2. 결과판정및분석기본선별검사의경우에는각검사기관이수행하고있는종목에대해검사를실시하여결과수치와함께정상및비정상여부를판정하여회신하도록하였다. 검사결과로부터각검사기관에서판독하는정상및비정상여부의판정결과에대해분석하였다. MS/MS를이용한광범위선별검사의경우 AC 및아미노산결과수치와함께정상및비정상여부판정, 판정기준치 (cut-off) 등을회신하도록하였다. 결과분석시수치결과에대해서는해당검사방법을이용한응답기관이 3개이상인경우중앙값, 최소및최대값을제공하였고, 10개이상일경우에평균, 표준편차, 변이계수를제공하였다. 결과분석은응답기관에대해판정결과및판정일치율과각기관에서사용하고있는판정기준치에대한평균, 중앙값, 최저값, 최고값에대해분석하였고, 각기관의검사성적에대한비교평가그래프를제공하였다. 유기산및아미노산검사는소수의기관만검사를수행하므로측정값을비교할수있도록각기관이보고한주요성분에대한항목과측정값을제공하였으며, 신빙도조사물질제조시의도한진단명을정답으로간주하고각기관에서제출한최종진단명에대하여정오답여부를판정하였다. 기타정량결과값에대해서도대부분의종목이참여기관수가많지않아통계분석이어려우므로, 해당기관에서보고한결과값을전체기관결과값의분포범위상에서확인할수있도록분포표를제공하였다. 수탁기관에대한정도관리인증기준은참가기관수 5 개이상이면서결과판정일치율이 70% 이상인기본선별검사종목을대상으로, 종목별보고결과의정답일치율 80% 이상, 참가한종목전체보고결과의정답일치율 90% 이상인경우이다. 결과 1. 참여기관및회신율 2016년도및 2017년도신빙도조사에서의전체 16기관의회신율은 100% 로각기관에서실제로시행하고있는검사들에대해모두신빙도조사에참가및회신하였다. 기본선별검사 6 항목은 2013년도이후로본신빙도조사에지속적으로총 16기관이참여해왔으나, 2017년도 2차에는 1기관이줄어든총 15 기관이참여하였다. MS/MS를이용한광범위선별검사항목에대해서는예년과마찬가지로총 15기관이신빙도조사에참여하였다. VMA검사는 7기관이지속적으로참여하였고, MMA 검사는 4-5개기관이참여하였다. 아미노산검사는회차별로 5-6기관, 유기산검사는 2-4기관이참여하였다. 카테콜라민과메타네프린종목에대해서는각회차별로소변과혈액검체를각각 3개씩발송하였으며, 6-7개기관이회신하였다. 2. 검사법및장비현황 6개질환에대한기본신생아선별검사에이용되는검사방법은 Fig. 1과같았다. 기본선별검사에는효소비색법, 효소면역측정법, 형광면역법, MS/MS법등이이용되어왔다. 갈락토오스혈증, 선천성부신과형성증, 선천성갑상선기능저하증선별검사는모든참여기관에서면역분석법으로검사를시행하고있다. 한편, MSUD, HCY 선별검사의경우현재모든기관에서 MS/MS법을활용하고있는것으로나타났으며, PKU검사에대해서는총 16기관중 15기관에서 MS/MS법을사용하여결과를보고하였다. VMA, MMA, 유기산검사에는액체크로마토그래피 (liquid chromatography) 또는액체크로마토그래피-탠덤질량분석법 (liquid chromatography tandem mass spectrometry), 가스크로마토그래피-질량분석법 (gas chromatography-mass Galactosemia Congenital hypothyroidism (T4) MS/MS FIA EIA ECA Congenital hypothyroidism (TSH) Congenital adrenal hyperplasia Homocystinuria Maple syrup urine disease Phenylketonuria (%) 100 Fig. 1. Analytical methods used for conventional neonatal screening tests of the first trial in Abbreviations: MS/MS, tandem mass spectrometry; FIA, fluorometric immunoassay using a Perkin-Elmer kit; EIA, enzyme immunoassay; ECA, enzyme colorimetric assay; T4, thyroxine; TSH, thyroid-stimulating hormone. 138 J Lab Med Qual Assur 2018;40:

4 spectrometry) 이주로이용되었으며, 아미노산분석에는액체크로마토그래피-탠덤질량분석법또는아미노산분석기 (amino acid analyzer) 가이용되었다. 요중및혈중카테콜라민과메타네프린검사에있어서는액체크로마토그래피또는액체크로마토그래피-탠덤질량분석법이이용되었다. 3. 신빙도조사결과 6종기본선별검사의각항목별정답률현황은 Table 2에정리하였다. MS/MS검사상포함된각항목에대한판정기준치의분포는 Table 3와같았으며, 신생아선별검사에대해서는모든검사항목별로각기관들에서보고한결과수치와해당판정기준치를상대적으로비교가능하도록그래프로제공하였다. MMA 및 VMA에대한신빙도조사결과는 Table 4, 카테콜라민과메타네프린검사결과는 Table 5와 Table 6, 아미노산분석결과는 Table 7, 유기산분석결과는 Table 8에제시하였다. 고찰 선천성대사이상질환조기발견을위한신생아선별검사대상신빙도조사사업은 1997년에처음시행되었으며, 2002년도부터는매년 2회씩시행되고있다. MS/MS를이용한광범위선별검사에대한신빙도조사사업은 2007 년도부터시작하였고, 2011년도부터는아미노산, 유기산, MMA, VMA 등을포함하여종목확대를위한노력이계속되었다. 2014년도에는요중카테콜라민, 메타네프린종목을, 2016년도부터는혈중카테콜라민및메타네프린종목까지추가되었다. 정도관리검체는상품화된정도관리검체와자가제조검체를혼용하여사용해왔는데, 정상과비정상수치, 판정기준치주변수치가모두포함 되도록하기위해자가제조검체의비중을점차더욱높이게되었다. 특히신생아선별검사의경우각항목별검체의수를증가시키고판정기준치보다경미한상승수치를보이는검체까지도포함시키므로써신빙도조사를통한각기관의검사수행능및문제점을보다정확히파악하고개선하는데도움을주고자하였다. 그결과, 판정의불일치를보인항목들이일부항목들또는일부기관에서발견되었다. 판정불일치를보인기관들은판정기준치주변수치를보이는검체에대해판정기준치는타기관과별로차이가없으면서수치결과가타기관에비해차이를보이거나, 수치결과는비슷하지만해당기관에서이용중인판정기준치가타기관과차이가있어최종판정이달라지는경우였다. 기본신생아선별검사종목과 MS/MS를이용한광범위선별검사에대한결과판정시, 결과를보고한기관들에서 80% 이상의일치를보이는결과를의도된정답으로간주하였고, 기관간일치율이낮은경우와검체이상이의심되는경우등에대해서는판정보류대상으로결정하였다. 국가지원대상인기본 6종검사중 MS/MS로검사가가능한 3가지항목들에대해서는수년전부터페닐케톤뇨증검사만을면역분석법으로시행하는 1개기관을제외하고는모두 MS/ MS검사법이활용되고있으며검사의일치율이높았다. T4나 TSH항목의경우에는다양한종류의정도관리물질확보가힘들며기관별검사방법이달라항상어려움을겪는데, 특히판정기준치에인접한측정값을나타내는항목들은결과판정일치율이낮아판정보류로결정한항목들이있었다. 이러한검체들에대한분석결과들에대해서는기관별측정값, 측정방법, 판정기준치의차이와그에따른판정결과의차이, 재검률에대해각기관자체적으로면밀한고찰이필요하겠다. 특히대부분의기관에서선별검사양성으로보고한비정상검체에대해 Table 2. Results of the proficiency testing of conventional neonatal screening tests in 2016 Variable 1st trial 2nd trial No. of institutions Proportion of correct answers (%) No. of institutions Proportion of correct answers (%) Phenylketonuria /192 (99) /192 (100) Galactosemia /180 (99) /165 (100) Congenital adrenal hyperplasia /168 (100) /168 (100) Maple syrup urine disease /180 (99) /180 (100) Homocystinuria /180 (100) /180 (100) Congenital hypothyroidism Thyroid-stimulating hormone /150 (100) /150 (100) T4, total 8 80/80 (100) 9 81/81 (100) T4, free 6 42/42 (100) 5 42/45 (93) Abbreviation: T4, thyroxine. J Lab Med Qual Assur 2018;40:

5 Table 3. Cut-off values used in expanded neonatal screening tests using tandem mass spectrometry in the first trial in 2016 Variable Unit Mean Median Minimum Maximum No. of institutions Amino acids Alanine umol/l , Arginine umol/l Aspartate umol/l Citrulline umol/l Glutamate umol/l Glycine umol/l , , Histidine umol/l Leucine+isoleucine umol/l Methionine umol/l Ornithine umol/l Phenylalanine umol/l Proline umol/l Tyrosine umol/l Valine umol/l Methionine/phenylalanine Phenylalanine/tyrosine Acylcarnitines C0 umol/l C2 umol/l C3 umol/l C4 umol/l C5 umol/l C6 umol/l C8 umol/l C10 umol/l C12 umol/l C14 umol/l C16 umol/l C18 umol/l C5DC umol/l C5OH umol/l C3/C C5/C C8/C C5/C C5/C C8/C J Lab Med Qual Assur 2018;40:

6 Table 4. Proficiency testing results for methylmalonic acid and vanillylmandelic acid Variable Trial Specimen no. No. Methylmalonic acid (mg/l) Mean±standard deviation Coefficient of variation (%) Median Minimum Maximum st CMM ± CMM ± CMM ± nd CMM ± CMM ± CMM ± st CMM ± Vannillymandelic acid (mg/l) CMM ± CMM ± nd CMM ± CMM ± CMM ± st CMV ± CMV ± CMV ± nd CMV ± CMV ± CMV ± st CMV ± CMV ± CMV ± nd CMV ± CMV ± CMV ± 위음성결과를보인다면문제가될수있다. MS/MS를이용한광범위선별검사는수십종의항목을동시에분석하고관련성분들과해당질환에서의증감양상등을고려하셔종합적으로판정하는검사이기때문에개별성분의수치값자체가절대적으로중요한것은아니다. 또한표준화된검사가아니라각기관에서사용하는장비와시약, 분석조건이달라얻어지는결과수치도차이를보일수있고, 해당기관의검사자료를기반으로자체적으로설정한판정기준치를활용해이상결과여부를판정하게된다. 2017년도부터는정도관리협회방침에따라수치결과에대한상세통계분석결과도제공되었는데, 본신빙도조사에서수치결과는최종판정대상이아니며참고자료로이용하면도움이될수도있다. 광범위선별검사에서도개별종목별로보면일부종목에서판정불일치가관 찰되었으며, 이들기관에서는자체적으로기관내판정기준치및검사방법에대한검토후필요시조치할것이권장된다. 특정종목에서반복적으로판정불일치를보이는경우라든가판정기준치가타기관에비해유의하게다른경우에는전체검사결과에대한분포그래프를타기관들과비교하면서살펴보는것이도움이될것이다. 신빙도조사에서나타난바와같이현재각기관들에서사용중인판정기준치수치는종목에따라 2 배이상차이를보이는경우가흔하다. 기관자체적으로주기적인판정기준치검증을시행하는것이필수적인사항이며, 본신빙도조사결과분석자료를타기관과의판정기준치차이, 검사결과수치분포의차이를파악하는데활용하면되겠다. 또한 MS/MS검사에서일부항목들에대하여보고하지않는기관의경우자체적인검토를통하여보고항목으로추가를검토할 J Lab Med Qual Assur 2018;40:

7 Table 5. Proficiency testing results for catecholamines Variable Year Trial Specimen no. No. Catecholamines, plasma (pg/ml) Mean±standard deviation Coefficient of variation (%) Median Minimum Maximum Dopamine st CMCP ± ,510.7 CMCP ± CMCP ± nd CMCP ± CMCP ± CMCP ± st CMCP ± CMCP ± CMCP ± nd CMCP ± CMCP ± CMCP ± Epinephrine st CMCP ± CMCP ± CMCP ± nd CMCP ± CMCP ± CMCP ± st CMCP ± , ,211.6 CMCP ± CMCP ± nd CMCP ± CMCP ± , ,238.9 CMCP ± Norepinephrine st CMCP ± , , ,570.4 CMCP ± CMCP ± , nd CMCP ± CMCP ± ,087.5 CMCP ± , , st CMCP ± , , ,347.1 CMCP ± , ,109.8 CMCP ± nd CMCP ± CMCP ± , , ,395.7 CMCP ± , ,097.2 (Continued to the next page) 142 J Lab Med Qual Assur 2018;40:

8 Table 5. Continued Variable Year Trial Specimen no. No. Catecholamines, urine (ng/ml) Mean±standard deviation Coefficient of variation (%) Median Minimum Maximum Dopamine st CMU ± CMU ± CMU ± nd CMU ± CMU ± CMU ± st CMU ± CMU ± CMU ± nd CMU ± CMU ± CMU ± Epinephrine st CMU ± CMU ± CMU ± nd CMU ± CMU ± CMU ± st CMU ± CMU ± CMU ± nd CMU ± CMU ± CMU ± Norepinephrine st CMU ± CMU ± CMU ± nd CMU ± CMU ± CMU ± st CMU ± CMU ± CMU ± nd CMU ± CMU ± CMU ± c J Lab Med Qual Assur 2018;40:

9 Table 6. Proficiency testing results for metanephrines Variable Year Trial Specimen no. No. Metanephrines, plasma (nmol/l) Mean±standard deviation Coefficient of variation (%) Median Minimum Maximum Metanephrine st CMMP ± CMMP ± CMMP ± nd CMMP ± CMMP ± CMMP ± st CMMP ± CMMP ± CMMP ± nd CMMP ± CMMP ± CMMP ± Normaetanephrine st CMMP ± Metanephrines, urine (ng/ml) CMMP ± CMMP ± nd CMMP ± CMMP ± CMMP ± st CMMP ± CMMP ± CMMP ± nd CMMP ± CMMP ± CMMP ± Metanephrine st CMU ± CMU ± CMU ± nd CMU ± CMU ± CMU ± st CMU ± CMU ± CMU ± nd CMU ± CMU ± CMU ± (Continued to the next page) 144 J Lab Med Qual Assur 2018;40:

10 Table 6. Continued Variable Year Trial Specimen no. No. Mean±standard deviation Coefficient of variation (%) Median Minimum Maximum Normaetanephrine st CMU ± , , ,455.4 CMU ± CMU ± , , , nd CMU ± CMU ± , , ,499.7 CMU ± , , , st CMU ± CMU ± , , ,442.7 CMU ± , , nd CMU ± , , ,393.9 CMU ± , , ,475.0 CMU ± Table 7. Proficiency testing results for amino acid analysis (unit, µmol/l) Year Trial Specimen no. Intended response Reported respons No. Reported components No. Median Minimum Maximum st CMA Homocystinuria Homocystinuria 5 Methionine 5 1, ,520 Homocystine CMA Hyperornithinemia Hyperornithinemia 3 Ornithine 5 1, ,629 HHH syndrome 2 2nd CMA Hyperlysinemia Hyperlysinemia 5 Lysine 5 2, ,210 CMA Hyerglycinemia Hyerglycinemia 5 Glycine 5 2,162 1, ,478 Alanine st CMA MSUD MSUD 4 allo-isoleucine CMA No abnormality No abnormality 4 No abnormality 1 Isoleucine ,154 MSUD 1 Leucine Valine 5 1, ,191 2nd CMA Tyrosinemia type I Tyrosinemia type I 5 Methionine CMA No abnormality No abnormality 6 Hypermethioninemia 1 Tyrosine Abbreviations: HHH, hyperornithinemia-hyperammonemia-homocitrullinuria; MSUD, maple syrup urine disease. 것이권장된다. 관련성분의상대적비율을관찰하면진단의정확성을향상시키는데도움이되며, 신빙도조사결과에따르면 phenylalanine/tyrosine과 C3/C2 비율등주요항목은현재모든기관에서적용하고있는것으로나타났다. 유기산검사는각회차별 2검체씩을발송해오다가 2017 년 2차시기부터 3검체씩으로증가시켰으며, 질환명과판정기준치이상의증가를보이는유기산들을보고하도록하였다. Malonic academia, glutaric aciduria, PKU와같은전형적인증감양상을보이는검체와정상인검체, 그리고 lactic acidosis, ketosis를시사하는비특이적소견의검체도포함되 J Lab Med Qual Assur 2018;40:

11 Table 8. Proficiency testing results for organic acid analysis (unit, mmol/mol creatinine) Year Trial Specimen no. Intended response Reported respons No. Reported components No. Median Minimum Maximum st CMO Malonic acidemia Malonic acidemia 3 Malonic acid CMO Glutaric aciduria (type 2) Glutaric aciduria (type 2) 3 Glutaric acid Ethylmalonic acid nd CMO Hyperoxaluria Hyperoxaluria 2 Glycolic acid CMO No abnormality detected No abnormality detected 2 Oxalic acid st CMO Phenylketonuria Phenylketonuria 3 Phenyllactic acid nd CMO No abnormality detected CMO Lactic acidemia/ ketosis CMO No abnormality detected CMO N-Acetylaspartic aciduria CMO Short chain acyl-coa dehydrogenase deficiency No abnormality detected 3 Phenylpyruvic acid hydroxyphenyllactic acid Lactic acidemia 2 Lactate Ketosis 1 4-hydroxyphenyllactic acid No abnormality detected N-Acetylaspartic aciduria Short chain acyl-coa dehydrogenase deficiency 4 2-hydroxybutyric acid hydroxybutyric acid hydroxyisobutyric acid N-acetylaspartic acid , Ethylmalonic acid Methylsuccinic acid hydroxybutyric acid 었다. 원래검체제조시의도한질환명을정답으로간주하였는데, 모든기관에서합당한질환명을제시하였다. 하지만, 해당검출물질에대한상승정도는기관별로상당한차이를보였고증가한것으로보고한성분이다소차이를보이는경우도있었다. 다만, 제조시양성으로의도한성분이검출되지않거나다른농도를보인경우도있는데, 검체운송이나취급상의문제일가능성을배제할수없다. 아미노산검사는회차별 2개검체를발송하였다. 예년신빙도조사에서는각기관이제출한측정값을제시하는것으로평가를대신해왔었는데이번신빙도조사에서는최종결과해석을중심으로판정하였다. 유기산검사와마찬가지로원래검체 제조시의도한질환명을정답으로간주하였는데, 해당대사이상질환에대한전형적인양상을보이는검체에대해서는대부분의기관에서보고한진단명이일치하였으나일부검체에대해다른질환명을제출한기관이있었고검체바뀜또는결과입력오류가의심되는사례도나타났다. 양성으로보고한아미노산성분들의수치결과를보면, 역시그상승정도는기관별로차이를보였으며, 검사법의차이또는검체운송이나보관상의문제가원인일가능성도있겠다. MMA, VMA항목의경우 2017년도 2차시까지각각 5기관, 7기관이참여하였다. 다른종목들에비하면 coefficient of variation (CV) 25% 이내로모든기관에서비교적유사한측 146 J Lab Med Qual Assur 2018;40:

12 정결과값을보고하였다. 요중카테콜라민은저농도의검체 1 개를제외하고는 CV 20% 이내였다. 요중메타네프린항목에대해서는총 7개기관에서신빙도조사에참여하였으며, 응답한모든기관에서유사한측정결과값을보고하여 CV 20% 였다. 단, 실제임상검사에서는카테콜라민과메타네프린이무작위뇨가아닌 24시간요를대상으로하기때문에요수집의적정성이검사결과에영향을미치는다른변수가될것이고, 본신빙도조사에서는최종보고결과와참고치는비교해볼수는없는한계점이있다. 혈중메타네프린은전체적으로기관별보고결과수치에상당한차이가있으며 CV 100% 이상을보인경우도있었는데, 검사대상인혈중농도자체가낮은범위에있고검사가표준화되지않았으며, 검체안정성의문제도배제할수없다. 선천성대사이상질환조기진단을위한신생아선별검사는검사수치뿐아니라결과에대한정상및비정상에대한적절한판독이매우중요하다. 그러나각기관에서검사에사용하는시약과검사방법이다양하고정상및비정상을평가할기준치가서로다른경우가많았다. 또한본신빙도조사에서겪는애로사항으로동일검사법이용기관의수가적은경우비교불가한점, 다양한질환양성검체를대량확보하기어려운점, 단일성분만이아닌다수의증감양상이조합된검체를준비해야하는점등이있었다. 아미노산이나유기산은대사이상질환의확진에중요하므로주요성분의검출과적절한결과해석이이루어지도록검사를시행하는소수의기관에서는각별한주의를기울여야하겠다. 특수대사산물의경우최근검사에대한관심과요구도가높아지고있으며앞으로시행기관이더늘어날것으로전망해본다. 각기관에서는신빙도조사결과를자체적으로도면밀히검토분석하여분석법의신뢰성을확인하고내부정도관리를강화함과동시에주기적으로기준치를검증하고결과보고종목및결과해석의차이도점검해보는것이매우중요할것으로생각된다. 앞으로도종목확대, 적절한정도관리물질의확보, 관련인력교육을포함하여지속적으로신빙도조사프로그램을개선ㆍ발전시킬수있는방향을모색한다면검사의질향상에기여할수있을것으로생각된다. 감사의글 정도관리물질제조관리와결과자료정리등본신빙도조사를위해수고해주신삼성서울병원진단검사의학과특수화학검사실지옥자선생님들비롯한직원여러분들과임상강사선생님께감사드린다. REFERENCES 1. Song J, Kwon KC, Kim JH, Kim JW, Min WK, Lee SY, et al. Annual report on external quality assessment in metabolic disorders in Korea (2007). J Lab Med Qual Assur 2008;30: Lee SY, Kwon KC, Kim JH, Kim JW, Park BT, Park HD, et al. Annual report on external quality assessment in biochemical genetics in Korea (2011). J Lab Med Qual Assur 2012;34:S Lee SY, Kwon KC, Kim JH, Kim JW, Park BT, Park HD, et al. Annual report on external quality assessment in biochemical genetics in Korea (2012). J Lab Med Qual Assur 2013;35:S Lee SY; Biochemical Genetics Subcommittee, The Korean Association of Quality Assurance for Clinical Laboratory. Annual report on external quality assessment of biochemical genetics in Korea (2013). J Lab Med Qual Assur 2014;36: Lee SY, Ji OJ, Kwon GC, Kim JW, Park HD, Song J, et al. Annual report on the external quality assessment scheme for biochemical genetics in Korea (2014). J Lab Med Qual Assur 2015;37: Lee SY, Ji OJ, Kwon GC, Kim JW, Park HD, Song J, et al. Annual report on the external quality assessment scheme for biochemical genetics in Korea (2015). J Lab Med Qual Assur 2016;38: J Lab Med Qual Assur 2018;40:

13 대사물질검사신빙도조사결과보고 ( ) 이수연성균관대학교의과대학삼성서울병원진단검사의학과 2016 년도및 2017 년도신생아선별검사및특수대사산물검사에대한신빙도조사사업은연간총 2 회시행되었다. 각회차별로페닐케톤뇨증, 갈락토오스혈증, 선천성부신형성과다증, 단풍당뇨증, 호모시스틴뇨증, 선천성갑상선기능저하증을포함하는선천성대사질환기본선별검사와탠덤질량분석기를이용한광범위선별검사를위한총 44 개의건조혈액여과지검체를 16 기관에발송하였다. 회신율은 100% 로, 타기관으로위탁을보내는검사항목은제외하고각기관에서실제로시행하고있는검사들은모두참가하였다. 판정기준치에인접한값을보이는검체들이포함되어결과판정일치율이낮아판정보류를한경우들이있었다. 타기관과차이나는측정값또는판정을보이는경우에는기관별측정값, 측정방법, 판정기준치의차이와그에따른판정결과의차이나결과해석방법등에대해각기관별로면밀한자체검토가필요할것으로판단되었다. 이외메틸말론산과바닐만델산, 유기산, 아미노산, 카테콜라민및메타네프린항목에대한신빙도조사도시행되었으며대부분만족스러운결과를보였다. 외부정도관리프로그램과지속적인교육을통하여검사의질을향상시킬수있을것으로기대된다. (J Lab Med Qual Assur 2018;40: ) 교신저자 : 이수연우 )06351 서울시강남구일원로 81, 성균관대학교의과대학삼성서울병원진단검사의학과 Tel: 02) , Fax: 02) , suddenbz@skku.edu 148 J Lab Med Qual Assur 2018;40:

REPORT ON PROFICIENCY TESTING Annual Report on the External Quality Assessment Scheme for Special Protein

REPORT ON PROFICIENCY TESTING https://doi.org/10.15263/jlmqa.2018.40.2.85 Annual Report on the External Quality Assessment Scheme for Special Protein in Korea (2017) Hyung-Doo Park Department of Laboratory