血清氯化物酶法测定

目的　建立血清氯化物的α 淀粉酶及其底物 2 氯 4 硝基苯 α D 麦芽三糖苷 (CNP G3)直接测定方法。方法　根据氯离子是α 淀粉酶的激动剂原理建立氯化物测定方法 ,并做方法学评价。结果　测定结果的平均偏差率为 0 4 6 % ;线性范围 5 0～1 5 0mmol/L ;平均回收率为 1 0 0 6 2 % ;批内CV <1 2 4 % ,日间CV <1 86 % ,总CV1 4 5 %～ 2 2 4 % ;加入高浓度的维生素C、葡萄糖、蔗糖、果糖、α 淀粉酶、三酰甘油、血红蛋白、胆红素、钙离子、溴离子、碘离子、氟离子、硫氰酸钾、对硝基酚、叠氮钠和硫酸铵均未显示干扰。与硫氰酸汞比色法 (MTC) ( x±s)比较 :MTC法 (X) :(95 6 6± 1 4 .4 5 )mmol/L ,酶法 (Y) :(95 6 2± 1 4 .93)mmol/L ,t=0 .0 78,P >0 5 ,Y =1 .0 1 6X - 1 .5 87,r=0 .984 ,n =93,P <0 .0 0 1 ;与离子选择电极法 (ISE) ( x±s)比较 :ISE法 (X) :(99.0 0±1 3.1 1 )mmol/L ,本法 (Y) (98.6 1± 1 2 .70 )mmol/L ,t=0 .1 4 0 ,P >0 .5 ,Y =0 .96 2X +3.375 ,r=0 .993,n =4 4 ,P <0 .0 0 1。溶解的工作试剂 (R1、R2 ) 2～ 8℃冷藏至少可以稳定 1 4天。结论　该方法测定成本低 ,准确、精密、线性范围宽 ,稳定性好 ,在抗卤族元素溴、碘及硫氰酸等阴离子的干扰方面 ,显著优于其他方法     

单一稳定液体试剂直接测定α-淀粉酶

目的 :建立以α- 2 -氯 - 4-硝基苯 -半乳糖吡喃麦芽糖苷 ( Gal- G2 - CNP)作底物的α-淀粉酶 (α-amylase)的直接测定方法。方法 :利用国外最新合成的 Gal- G2 - CNP( alpha- 2 - chloro- 4- nitrophenyl-galactopyranosylmaltoside)作底物 ,用速率法测定α-淀粉酶活力。结果 :线性范围可达 30 0 0 U/L ( r=0 .9998) ,变异系数为 0 .30 %～ 0 .53%。与宝灵曼公司的 ET- G7- PNP法 〔1〕的相比 :r=0 .9998,Y=0 .76X 0 .2 0 ( n=2 0 0 ) ,与 G3 - CNP的相比 r=0 .9999,Y=1 .0 1 X 1 1 .7( n=2 0 0 )。结论 :简便、直接、灵敏、经济、试剂单一稳定、反应转化率高、线性范围宽、基质本身自然水解极微 ,各项指标符合国际临床化学学会( IFCC)提出的“理想的淀粉酶检测方法”的要求〔2〕。适于各种类型的自动分析     

非胰腺炎高脂血症孕妇不同孕期血淀粉酶水平变化及其与血脂水平的关系

目的探讨非胰腺炎高脂血症孕妇处于不同孕期时外周血淀粉酶水平的变化及其与血脂水平的关系。方法采用横断面研究分析法将986名孕妇按孕期分为早、中、晚孕期3组,同时选取非孕体检健康女性200名为对照组,同时检测总胆固醇(TC)、三酰甘油(TG)及α-淀粉酶(α-AMY)的水平,对检测结果进行统计分析。结果中、晚孕组TG水平分别为(2.17±0.62)、(2.73±0.58)mmol/L,高于对照组(1.16±0.54)mmol/L;晚孕组α-AMY水平为(78.42±19.41)U/L,与对照组(50.92±18.93)U/L相比,差异有统计学意义(P0.05),外周血中α-AMY的水平与TG水平具有相关性(r=0.56,P0.05)。妊娠期妇女外周血晚孕组α-AMY水平为(78.42±19.41)U/L,与中孕组(57.19±17.62)U/L相比,差异有统计学意义(P0.05)。其中,晚孕组2名孕妇并发急性胰腺炎。妊娠期妇女外周血α-AMY与TG这两个变量之间存在中度正相关关系(r=0.56,P0.05)。结论孕晚期妇女外周血α-AMY水平的升高可能是由高脂血症导致胰腺高负荷引起,对于妊娠后期高血脂孕妇建议产前检查血淀粉酶水平,可以对妊娠期急性胰腺炎进行早期诊断,正确评估病情并尽早采取干预措施,提高母婴预后。     

血清1- 硬脂酰-sn- 甘油-3- 磷酰胆碱水平检测对妊娠期糖尿病的诊断价值

目的 探讨血清1- 硬脂酰-sn- 甘油-3- 磷酰胆碱(1-stearoyl-sn-glycero-3-phosphorylcholine, LPC18:0)水平检测对妊娠期糖尿病(gestational diabetes mellitus, GDM)的诊断价值。方法 选择2020 年5 ～ 12 月在枣庄市妇幼保健院进行产前检查的孕妇60 例为研究对象,根据口服葡萄糖耐量试验(oral glucose tolerance test,OGTT) 测定结果将妊娠妇女分为GDM 孕妇(观察组)30 例和糖耐量正常孕妇(对照组)30 例。利用液相色谱- 串联质谱(liquidchromatography-tandem mass spectrometry, LC-MS/MS)的代谢组学技术检测两组孕妇血清 LPC18:0 表达水平,分析GDM 孕妇血清LPC18:0 水平与临床、糖脂指标的相关性,利用受试者工作特征曲线(receiver operating characteristiccurve,ROC)评价血清中LPC18:0 诊断GDM 的价值。结果 观察组LPC 18:0[100.42(76.80,142.08)μg/ml]、总胆固醇(TC)(3.52 ± 0.51 mmol/L )、空腹血糖(FPG)(5.31 ± 2.12 mmol/L )、低密度脂蛋白- 胆固醇(LDL-C)(3.81± 0.98 mmol/L)、空腹胰岛素(FINS)(16.65 ± 6.78μIU/ml)、胰岛素抵抗指数(HOMA-IR)(3.32 ± 1.08)和糖化血红蛋白(HbA1c)(5.61 %± 0.31 %)水平均高于对照组［30.88(22.08,40.60) μg/ml,3.12 ± 0.68 mmol/L,5.01 ± 1.47 mmol/L,3.42 ± 0.52 mmol/L, 10.98 ± 4.89 μIU/ml,2.27 ± 0.99 ,5.01 %± 0.50 %］,差异有统计学意义(z=-5.28,t=2.48 2.83,3.01,3.43,4.43,5.34,均P ＜ 0.05)。观察组和对照组孕妇三酰甘油(TG)(2.11 ± 0.47mmol/L vs 1.91 ± 0.82 mmol/L),高密度脂蛋白- 胆固醇(HDL-C)(1.98 ± 0.38 mmol/L vs 2.01 ± 0.56 mmol/L)水平比较,差异均无统计学意义(t=0.66,-0.67,均P ＞ 0. 05)。GDM 孕妇血清LPC18:0 水平与孕妇年龄、孕前体重指数,TG,HDL-C,HbA1c 水平无相关性(r=-0.14 ~ 0.17,均P ＞ 0.05),与FPG,TC,LDL-C 水平呈正相关(r=0.28,0.41,0.46,均P ＜ 0.05),与FINS,HOMA-IR 呈负相关(r= -0.33,-0.51,均P ＜ 0.05)。ROC 曲线分析结果显示,区别诊断GDM孕妇及正常孕妇时,血清LPC18:0 的曲线下面积(area under curve,AUC)为 0.988(95%CI: 0.964 ～ 1.000),当最佳临界值62.25 μg/ml 时,特异度和灵敏度分别为95% 和90%。结论 利用LC-MS/MS 方法检测GDM 孕妇血清LPC18:0 水平较正常孕妇明显升高,血清LPC18:0 水平检测对GDM 有一定的诊断价值。     

氧化法测定血清超氧化物歧化酶及临床应用

目的 探讨氧化法测定血清超氧化物歧化酶(SOD)及临床应用价值.方法 根据测定条件采用氧化法直接测定血清SOD,对其精密度、准确度、线性、干扰性等性能进行评价.结果 批内CV<2.83%,批间CV<3.98%,总CV<4.01%,回收率达101.3%,线性:0～250 U/ml(Y=0.980 2X+6.254 2,R2=0.992 3);加入TG<3.5 mmol/L,BIL<200 μmol/L;Hb<100 g/L时无显著干扰;血清生物参考区间值(±2s)130～220 U/ml.结论 在生化仪上进行血清超氧化物歧化酶检测方便、准确、快速.     

血浆置换治疗在慢性重型乙型肝炎中的疗效探讨

目的 探讨血浆置换(PE)治疗对慢性重型乙型肝炎(CSHB)患者的血清炎性介质及肝功能的影响。方法 分析2013年2月~2014年2月在武汉大学人民医院感染性疾病科接受治疗的CSHB患者的临床资料。对所有入组患者实施PE结合临床的综合治疗方式,其中每次置换3L同型新鲜的冰冻血浆。比较入组患者治疗前后的炎性指标、肝功能指标。结果 本研究共纳入研究对象45例,平均年龄为42.3岁,治疗后患者的炎性指标包括CRP(28.5±11.3 mg/L vs.20.4±14.3 mg/L;t=3.613,P0.001)、TNF-α(275.4±50.9 vs.181.0±39.0;t=8.765,P0.001)、IL-6(351.9±41.5 pg/m L vs.252.9±34.8 pg/m L;t=12.262,P0.001)、IL-8(665.9±84.6 pg/m L vs.458.4±86.4 pg/m L;t=11.513,P0.001)水平均显著低于治疗前水平;入组患者治疗后的胆固醇(TCh)(2.1±0.3 mmol/L vs 2.5±0.8mmol/L;t=3.141,P0.001)、胆碱酯酶活力(CHE)(2635.9±984.6 U/m L vs 3448.4±566.3 U/m L;t=5.442,P0.001)、白蛋白(Alb)(28.6±3.5 g/L vs.31.2±2.7 g/L;t=8.753,P0.001)水平均显著高于治疗前,而PT(34.6±6.7 vs.26.6±4.3;t=6.741,P0.001)、丙氨酸转氨酶(ALT)(82.0±5.7 IU/L vs.55.9±5.0 IU/L;t=16.531,P0.001)、天门冬氨酸氨基转移酶(AST)(80.0±3.1 IU/L vs.53.4±2.4IU/L;t=15.563,P0.001)、总胆红素(TBIL)(15.7±0.82 mmol/L vs.13.4±1.3 mmol/L;t=10.326,P0.001)显著低于治疗前。结论 PE治疗能够显著改善CSHB患者的肝功能,改善机体炎症状况。     

复方α-酮酸片对慢性维持性血液透析患者近期营养状况的影响

目的 探讨口服复方α-酮酸片对血液透析患者近期整体营养状况的影响.方法 选择2011-2012年,于广州军区武汉总医院接受慢性维持性血液透析治疗的60例患者为研究对象.根据入院号通过计算机随机分组方式将其分为研究组和对照组,每组各30例.对照组患者仅给予常规的蛋白质食物治疗,而研究组患者在常规治疗基础上加服复方α-酮酸片,剂量为630mg/片×4片×3次/d(本研究遵循的程序符合广州军区武汉总医院人体试验委员会所制定的伦理学标准,得到该伦理会批准,分组征得受试对象本人的知情同意,并与之签订临床研究知情同意书).于治疗12周后,分析比较两组患者的人体测量学指标:体质量指数(BMI)、肱三头肌皮褶厚度、上臂肌围;以及主要血液生化指标:血红蛋白、血白蛋白、前白蛋白、三酰甘油及总胆固醇水平的变化.结果 治疗12周后,两组患者的BMI、肱三头肌皮褶厚度、上臂肌围3项人体测量学指标比较,差异无统计学差异(t=0.103,1.140,0.244;P＞0.05);研究组患者的总胆固醇和三酰甘油水平分别为(4.42±1.02) mmol/L和(1.42±0.23) mmol/L,均低于对照组的(4.94±0.89)mmol/L和(4.63±1.01) mmol/L,两组比较,差异有统计学意义(t=2.10,2.36;P＜0.05);研究组患者的血红蛋白、血白蛋白及前白蛋白水平分别为(98.15±3.12)g/L、(38.56±1.67)g/L和(336.34±20.12)mg/L,均高于对照组的(79.87±3.21)g/L、(35.23±1.32)g/L和(323.45±19.89)mg/L,两组比较,差异均有统计学意义(t=22.4,8.86,3.09;P＜0.05).结论 复方α-酮酸片能显著改善慢性维持性血液透析患者近期营养状况,但其长期疗效仍待进一步观察.     

日立7170生化分析仪离子选择电极内标液的研制与应用

目的探讨自配离子选择电极（ISE）内标液试剂能否应用于7170A生化分析仪的ISE模块测定。方法取自配ISE内标液,参照有关文件的内容,测定其理化参数,并评估精密度、准确度和线性范围,并与原装内标液同时检测45份患者样本,统计相关数据。结果自配内标液与原装内标液的主要理化参数[pH值、电导率、渗透压、无机离子浓度（K＋、Na＋、Cl^-）]基本一致。2种内标液测定K＋、Na＋、Cl^-（高、低值质控品）的精密度及准确度均无差异（P均〉0.05）。线性方程为K＋（1-10 mmol/L）：Y=0.997 5X＋0.021,r=0.999;Na＋（80-180 mmol/L）：Y=0.999 7X＋0.15,r=0.999;Cl^-（60-160 mmol/L）：Y=1.015 4X-2.51,r=0.989。自配内标液用于测定常规样本的结果与原装内标液的检测结果基本一致（P〉0.05）。结论自配的ISE内标液可替代原装试剂用于7170A生化分析仪ISE模块测定。     

亚临床动脉粥样硬化患者血脂水平和炎性因子与颈动脉内-中膜厚度关系分析

目的 探讨亚临床动脉粥样硬化(subclinical atherosclerosis,SAS)患者颈动脉内-中膜厚度与血脂水平和炎性因子的关系。方法 老年SAS患者88例,根据颈动脉中膜厚度分为内膜增厚组35例和斑块形成组53例,同期体检健康者88例为对照组,检测并比较3组三酰甘油、总胆固醇(total cholesterol,TC)、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇(low density lipoprotein-cholesterol,LDL-C)及血清高敏C-反应蛋白(high sensitivity C-reactive protein,hs-CRP)、白细胞介素-6(interleukin-6,IL-6)、肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)水平,比较SAS患者不同hs-CRP风险分层血脂水平差异。结果 内膜增厚组及斑块形成组LDL-C((3.98±0.30)、(4.15±0.10)mmol/L)、hs-CRP((2.85±0.20)、(3.50±0.20)mg/L)、IL-6((52.25±8.54)、(125.35±10.30)ng/L)及TNF-α((46.15±6.32)、(115.28±8.50)ng/L)均高于对照组((3.56±0.20)mmol/L、(0.57±0.10)mg/L、(20.56±5.75)ng/L、(18.32±3.25)ng/L)(P<0.05),斑块形成组hs-CRP、IL-6及TNF-α高于内膜增厚组(P<0.05),LDL-C与内膜增厚组比较差异无统计学意义(P>0.05);hs-CRP高危水平患者TC((53.87±2.27)mmol/L)、LDL-C((4.46±0.44)mmol/L)明显高于hs-CRP中危水平患者((43.65±2.80)mmol/L)、(3.56±0.18)mmol/L)(P<0.05)。结论 颈动脉内-中膜厚度与LDL-C及hs-CRP、IL-6、TNF-α水平相关;随炎性因子hs-CRP风险分层水平增加,LDL-C持续增高。     

C-反应蛋白与白细胞介素-6和肿瘤坏死因子-α在2型糖尿病肾病中的变化

目的 研究血清炎症因子C-反应蛋白(CRP)、白介素-6(IL-6)和肿瘤坏死因子-α(TNF-α)在2型糖尿病肾病中的变化.方法 2型糖尿病患者96例,其中2型糖尿病正常蛋白尿(DM)组38例,早期肾病(DN1)组31例,临床肾病(DN2)组27例,健康对照(NC)组30例,用酶联免疫吸附试验(ELISA)法测定血清CRP、IL-6、TNF-α水平.结果 DM组血清CRP 2.74±1.65 mg/L、IL-6 148.36±24.62 ng/L、TNF-α 16.50±8.90 ng/L较健康对照组升高,分别为0.89±0.45 mg/L、IL-6 123.20±18.59 ng/L、TNF-α 12.50±4.62 ng/L(P＜0.05);DN1、DN2两组的血清CRP、IL-6、TNF-α均较DM组、健康对照组升高(P＜0.05或P＜0.01);DN2组的血清CRP、IL-6、TNF-α均较DN1组升高(P＜0.05或P＜0.01).相关分析发现,血清CRP升高与总胆固醇(TC)(r=0.45,P＜0.01)、尿微量清蛋白排泄率(UAER)(r=0.545,P＜0.01)、血肌酐(Cre)(r=0.412,P＜0.01)及糖化血红蛋白(HbAlc)(r=0.22,P＜0.05)成正相关;血清IL-6与TC(r=0.289,P＜0.01)、UAER(r=0.0.387,P＜0.01)、血肌酐(r=0.361,P＜0.01)及糖化血红蛋白(HbAlc)(r=0.380,P＜0.01)成正相关;血清TNF-α与BMI(r=0.256,P＜0.01)、血Cre(r=0.251,P＜0.01)及UAER(r=0.231,P＜0.01)成正相关.结论 糖尿病肾病患者炎性反应因子水平升高与尿清蛋白排泄率成正相关,血清CRP、IL-6、TNF-α的测定可作为判断2型糖尿病肾病损害程度及预后的指标.     

Electrophoretic separation of high-density lipoprotein choelsterol evaluated and compared with the modified lipid research clinic procedure.

We evaluated a new agarose-gel-electrophoretic procedure (Corning) (I) for separating and quantitating of high-density lipoprotein cholesterol (HDLC), comparing it with the modified Lipid Research Clinics (LRC) procedure (heparin 183 kilounits/L, MnCl2 92 mmol/L) (II). Method I was insensitive to an HDLC concentration of 50 mg/L, but gave a linear dose-response curve between 130 and 1200 mg/L. Method II is sensitive to 50 mg/L and linear from 50--1200 mg/L. The within-plate CV for the Corning method varied from 26.2% for an HDLC of 168 mg/L to 6.8% for 580 mg/L. Within-day between-plate CV for the Corning method ranged from 22.1% at 155 mg/L to 8.0% at 651 mg/L, compared to 3.0 and 0.8% for the modified LRC procedure. Between-day CV for method I was 20, 12.6, 4.3, and 3.5% for HDLC concentrations of 175, 435, 542, and 678 mg/L, respectively; for method II it was 14, 5, 3.5, and 2.6%, respectively. Analysis of HDLC in 100 patients by both procedures showed mean HDLC values to be significantly lower (mean + SD, 27.8 +/- 1.7 mg/L; p less than 0.001) by method I. In 46 patients with HDLC less than 450 mg/L, this difference was accentuated (mean + SD = 40.5 +/- 2.6 mg/L) and clinically significant. Electrophoretic methods offer a promising further alternative method for HDLC separation and quantitation, but the negative bias, present limited sensitivity, and lack of precision at less than 450 mg/L indicate that they are not yet optimal for routine clinical use for patients with values less than 450 mg/L.     

Evaluation of a single-color-reading method for determining fructosamine

A commercial kit for determining fructosamine was evaluated. The reference interval (determined from data on 183 nondiabetic subjects) was 1.67 to 2.85 (mean 2.17) mmol/L. Serum and plasma (EDTA- or heparin-anticoagulated) gave equivalent results; plasma treated with fluoride/oxalate gave slightly lower values. The between-run CV was less than 4%. Fructosamine values were similar by the present method and the kinetic method. The standard curve was linear in the range of 1.3 to 8.5 mmol/L. None of several constituents of blood that we tested appreciably interfered. Fructosamine values were increased in some lipemic samples from non-diabetics, and were significantly correlated with glycated hemoglobin as measured by affinity chromatography. This kit evidently is a suitable alternative to the kinetic method for determining fructosamine.     

Quantitation of lactate by a kinetic method with an extended range of linearity and low dependence on experimental variables

We report conditions and characteristics of a new kinetic method for measuring lactate. Using a multiple linear regression method, we fit data for absorbance and for rate of change of absorbance to a modified rate form of the Michaelis-Menten equation. The principal objective of the fitting process is to compute the total absorbance change, delta A infinity, that would be measured if the reaction were monitored from the point of mixing to equilibrium. For data collected at 1-s intervals from 5 to 200 s, the fitting process gives values of delta A infinity that vary linearly with lactate concentration from 10.6 to 180 mumol/L in the reaction cell after 150-fold dilution of samples. For a range of enzyme activities that produced a 20% change in the initial rate, the regression-kinetic treatment yielded results with no detectable systematic error. The mean within-day CV was 2.1% for an average concentration of 14.4 mmol/L; the day-to-day CV was 5.2% for 3.90 mmol/L. For 25 samples of canine plasma with lactate concentrations from 2 to 26 mmol/L, comparison of results obtained with the regression-kinetic method (y) with results obtained with a commercially available equilibrium method (x) gave a least-squares equation of y = 1.01x - 10 mumol/L.     

Determination of serum triglycerides by an accurate enzymatic method not affected by free glycerol

In this automated single-run enzymatic procedure for specific determination of triglycerides in serum, free glycerol is removed from the reaction mixture by pre-incubation with glycerol phosphate oxidase and peroxidase. The subsequent addition of lipase and the chromogen, 4-aminoantipyrine, results in the formation of color proportional to the amount of triglycerides in serum. Standards containing triolein in aqueous detergent are used to calibrate the method. For serum pools from the Centers for Disease Control with target values of 0.74, 1.41, and 2.63 mmol/L, the method produced biases of +0.01, -0.05, and 0.00 mmol/L, respectively (mean: -0.01 mmol/L or -0.4%). The mean coefficient of variation was 1.4% within and 2.5% between days; the combined CV, 2.9%. Ninety 6-microL serum samples can be analyzed per hour. The method is more accurate and precise than one based on an NADH-coupled enzyme system with separate addition of lipase.     

低密度脂蛋白胆固醇保护性试剂匀相测定法的临床评价

目的 对低密度脂蛋白胆固醇(LDT-C)保护性试剂匀相测定法进行临床评价。 方法 分析了保护性试剂匀相测定法的精密度、准确性、特异性和干扰因素.并随机选取了219份病人血清标本,比较分析用保护性试剂匀相测定法直接测定与Friedewald公式和Planella公式计算的LDL—C结果。 结果 保护性试剂匀相测定法具有较好的精密度(批内、批间CV和总CV均小于3％)。线性范围至10.4mmol/L,最低检测浓度为0.08mmol/L,平均同收率为101.2％:基本不受极低密度脂蛋白(VLDL)、高密度脂蛋白(HDL)和血红蛋白的影响。在TG<4.52mmol/L时,用匀相测定法与Friedewald公式和Planella公式的计算法结果之间相关性良好,两种公式计算法结果之间的也有较好相关性;而在TG>4.52mmoL/L时,匀相测定法与两种计算法之间的相关性差。结论 保护性试剂匀相测定法简便、快速、结果准确,易于自动分析,适合在临床实验室常规检测应用。     

脲酶结合邻甲酚酞络合剂显色检测血清及尿液尿素含量

目的　建立一种实用的血清和尿液中尿素含量的比色测定方法。方法　脲酶水解尿素产生氨(NH3),使溶液pH升高,以邻甲酚酞络合剂(OCPC)作为pH指示剂,波长570nm吸光度变化与尿素浓度成正相关。结果　该法线性范围血清1.00～200mmol/L,尿液10.0～1000mmol/L;检测界限血清0.36mmol/L,尿液2.19mmol/L。精密度分析血清批内CV1.13%～2.78%,批间CV1.81%～3.91%,总CV2.13%～4.80%。尿液批内CV0.68%～1.72%,批间CV0.96%～2.24%,总CV1.17%～2.82%。平均回收率血清100%,尿液102%。该法(Y)与酶速率法(X)比较相关性良好(血清Y＝1.048X+0.511,r＝0.998,S     

Patient-derived quality specifications for instruments used in self-monitoring of blood glucose

BACKGROUND: Instruments for self-monitoring of glucose (SMBG) are increasingly used by diabetic patients. Information is limited on how patients use and interpret SMBG results, and no quality specifications for such instruments are based on the opinions of patients. METHODS: Type 1 diabetic patients (n = 201) filled in a questionnaire eliciting daily limits for blood glucose (BG) and changes of BG considered significant at different glucose concentrations. From these responses, patient-derived quality specifications were calculated in different clinical situations with low, intermediate, and high BG concentrations. RESULTS: Mean age of the patients was 31.8 years, mean diabetes duration was 14.7 years, and mean SMBG duration was 10.0 years with a mean frequency of 11.2 measurements/week. The threshold for hypoglycemic symptoms was 3.0 mmol/L (54 mg/dL), and the mean daily BG target window was 4.3-10.4 mmol/L (77-187 mg/dL). The mean absolute BG changes producing actions from the patients ranged from 1.1 mmol/L (20 mg/dL) to 3.6 mmol/L (65 mg/dL). The analytical quality specifications for imprecision depended on the clinical situation. Excluding the hypoglycemic situation, the analytical CV needed to fulfill the expectations of 75% of the patients was 6.4-9.7%. The analytical quality specification for CV at hypoglycemic concentrations was 3.1%. CONCLUSIONS: Instruments for self-measurements of glucose with an imprecision (CV) of < or = 5% and bias < or = 5% meet the expectations of >75% of patients in clinical situations other than hypoglycemia.     

Reliability of the Reflotron in the determination of cholesterol

Measurements of total cholesterol in the field by means of the Reflotron dry-chemistry system (capillary blood) were compared to total cholesterol obtained by a standardized conventional wet-chemistry method in a clinico-chemical laboratory (serum). A total of 1200 people participated in the study. Two identical Reflotron machines were used. In the first period of the study an excellent agreement was found between Reflotron measurements of a reference serum provided by the manufacturer (mean, 4.99 mmol/l; CV, 1.8%) and the stated value (4.97 mmol/l). In the rest of the study higher values and greater variation were found with the Reflotron (mean, 5.32 mmol/l; CV 5.2%). Clearly the Reflotron measurements in the latter period of study were not reliable. In the period with stable instruments most of the values obtained at the two Reflotron machines differed from each other by less than 10%, with a mean difference of 0.08 mmol/l. Reflotron (both machines) and wet-chemistry measurements agreed well for the first 500 participants in the study (mean difference, Reflotron-wet-chemistry, -0.008 mmol/l; 95% confidence interval, -0.035 to 0.019 mmol/l; correlation, 0.967). In this period most Reflotron values differed from wet-chemistry values by less than 9% below to 9% above. With the next 200 participants the Reflotron gave on average slightly higher values than wet-chemistry measurements. The coefficients of variation for measurement variation were higher for Reflotron that for wet-chemistry even in the period with stable instruments. In all parts of the study period a lower HDL-cholesterol level was associated with larger differences between total cholesterol determined by Reflotron and wet-chemistry.     

Multicentre evaluation of a new point-of-care test for the determination of CK-MB in whole blood

BACKGROUND: The point-of-care (POC) test Roche CARDIAC CK-MB is a new assay which has been developed for the existing Roche Cardiac reader system. METHODS: We performed a multicentre evaluation at six sites to assess the analytical performance of the POC CK-MB assay and to compare it with a quantitative laboratory CK-MB assay. RESULTS: Within-series coefficients of variation (CV) resulting from 34 ten-fold measurements with patient samples ranged from 4.3% to 16.4%. Using quality control material, the mean CV values for day-to-day imprecision were 6.5% for the low level control and 8.4% for the high level control. Based upon 847 pairs of values, the mean relative bias of three independently calibrated lots of the POC CK-MB assay ranged from -6% to -11% in method comparisons with the lab CK-MB assay. The mean relative lot-to-lot differences of POC CK-MB were between -2% and +1%. No interference was observed with lipaemic blood (triglyceride concentrations up to 8.1 mmol/L), icteric blood (bilirubin concentrations up to 513 micromol/L), haemolytic blood (haemoglobin concentrations up to 0.12 mmol/L), biotin (up to 30 mg/L) and rheumatoid factor (up to 119 IU/mL), or with 53 standard or cardiological drugs even in toxic concentrations. There was no influence on the results by varying haematocrit values in the range from 21% to 54%. A slight interference with human anti-mouse antibodies type 2 was found. No significant influence on the results with POC CK-MB was found by using sample volumes between 135 and 165 microL. High CK-MB concentrations above the measuring range of POC CK-MB (1-40 microg/L) did not lead to false low results due to potential high-dose hook effect. No significant effect of sample age on recovery occurred up to a sample age of 24 h. No cross-reactivity was found between the POC CK-MB assay and either CK-MM or CK-BB. A substudy with healthy individuals confirmed the reference limits of 3.8 microg/L for females and 6.7 microg/L for males. CONCLUSIONS: The POC CK-MB assay showed a very good analytical performance with an excellent concordance with the calibration and reference laboratory method. It should be therefore suitable for its intended use in POC settings. Clin Chem Lab Med 2008;46:630-8.     

Assessing quality assurance for sweat chloride testing.

Variations in sweat chloride tests were analyzed. A total of 1,806 sweat test results were analyzed for intra-assay and inter-assay variation in sweat chloride concentration and sweat weight. The mean and standard deviation of sweat chloride determinations for the negative population was 11.63 mmol/L (7.20 s.d.); for the borderline population was 50.01 mmol/L (6.27 s.d.); and for the positive population was 96.75 mmol/L (s.d. = 13.81). The percent of sweat tests that were negative was 86.77, borderline, 3.82, and positive, 9.41. The variation, represented as the standard deviation, between bilateral sweat chloride values on the same patient for negative results is 10.23 and for positive results is 14.60. The average variation within a patient with regard to sweat weight is 19%. Clinical laboratory scientists can use this information in assessing their own quality assurance procedures and patient results.