载脂蛋白B与A-1比值对预测血管疾病风险的价值

目的评价、比较载脂蛋白B与A-1比值（apoB/apoA-1）和其他5种血脂指数在心脑血管疾病风险预测中的价值,探讨apoB/apoA-1比值警示界线的划分。方法分析测量3 972例受试者血脂水平,计算：血浆致动脉硬化指数、动脉硬化指数以及低密度脂蛋白、胆固醇、三酰甘油分别与高密度脂蛋白的比值和apoB/apoA-1比值;分别依年龄、性别、apoB/apoA-1阈界进行分组比较。结果同性别不同年龄段apoB/apoA-1比值比较,〉60岁组女性最高（P〈0.01）,40～60岁组男性最高（P〈0.01）;年龄〉60岁者,apoB/apoA-1在阈界0.9时男、女阳性率分别为20.7%,25.8%;不同性别6项指数比较,男性apoB/apoA-1明显高于女性（P〈0.01）;以apoB/apoA-1阈界0.9分组比较各项血脂指数,apoB/apoA-1差异最大（F=2 909.01）。结论在预测心脑血管疾病上apoB/apoA-1比值优于其他血脂指数,是预测心脑血管疾病风险敏感、准确的指数,apoB/apoA-1≥0.9为警示界线。     

Dyslipidemia is a strong predictor of myocardial infarction in subjects with chronic kidney disease

Abstract

Aim. To evaluate dyslipidemia as predictor of myocardial infarction (MI) in subjects with or without chronic kidney disease (CKD). Methods. In 142,394 middle-aged Swedes referred for laboratory evaluation, glomerular filtration rates (GFR) were estimated using the Modification of Diet in Renal Disease study equation. CKD was defined as GFR 15–60 mL/min/1.73 m². Subjects were stratified into presence or absence of CKD, and lipid measures were related to MI using Cox's proportional hazards regression. Results. During 12 years of follow-up there were 5,466 MIs. The adjusted hazard ratio for MI for the highest versus the lowest quartile of the apolipoprotein (apo) B/apoA-1 ratio among individuals without CKD was 2.88 (95% confidence interval 2.54–3.26) and for those with CKD 3.35 (2.25–4.91). The corresponding estimates for the total cholesterol/high-density lipoprotein (HDL) cholesterol ratio were 3.13 (2.78–3.52) and 3.54 (2.43–5.17), respectively. Receiver operator characteristics analyses showed an advantage in the prediction of MI for the apoB/apoA-1 ratio as compared to conventional lipids (P < 0.0001). Conclusions. The ratio of apoB/apoA-1, the ratio of total cholesterol/HDL cholesterol, and non-HDL cholesterol were all strong predictors of myocardial infarction, both among subjects with and without renal dysfunction, with a possible advantage for the apoB/apoA-1 ratio.     

Combined use of high-sensitivity C-reactive protein and apolipoprotein B/apolipoprotein A-1 ratio prior to elective coronary angiography and oral glucose tolerance tests

Objectives

The study aimed to investigate the predictive value of the combination of high-sensitivity C-reactive protein (hs-CRP) and apolipoprotein B (apoB)/apoA-1 ratio for the outcomes of coronary angiography (CAG), echocardiography and oral glucose tolerance tests (OGTTs).

Design and methods

Hs-CRP, apoB, apoA-1, and the profiles of CAG, echocardiography and OGTTs as well as traditional risk factors were measured in 1757 cardiology patients.

Results

Hs-CRP or apoB/apoA-1 ratio was significantly correlated with the presence and severity of angiographic profiles, the levels of left ventricular (LV) ejection fraction, LV mass and LV mass index, and the presence of abnormal glucose metabolism. The combination of hs-CRP and apoB/apoA-1 ratio had greater correlation with abnormal glucose metabolism than its individual components in patients with normal fasting glucose, and was an independent predictor for coronary artery disease.

Conclusions

The combination of hs-CRP and apoB/apoA-1 ratio may be a strong predictor for coronary artery disease and abnormal glucose metabolism.     

Lipoprotein predictors of cardiovascular events in statin-treated patients with coronary heart disease. Insights from the Incremental Decrease in End-points through Aggressive Lipid-lowering Trial (IDEAL)

Background. Few studies have looked into the ability of measurements of apolipoprotein B (apoB) and apolipoprotein A-1 (apoA-1) or apoB/apoA-1 to predict new coronary heart disease (CHD) events in patients with CHD on statin treatment.

Aims. In the IDEAL trial, to compare lipoprotein components to predict CHD events and to what degree differences in those parameters could explain the observed outcome.

Methods. We compared the ability of treatment with atorvastatin 80 mg/day to that of simvastatin 20–40 mg/day to prevent CHD events in patients with CHD and used Cox regression models to study the relationships between on-treatment levels of lipoprotein components to subsequent major coronary events (MCE).

Findings. Variables related to low-density lipoprotein cholesterol (LDL-C) carried more predictive information than those related to high-density lipoprotein cholesterol (HDL-C), but LDL-C was less predictive than both non-HDL-C and apoB. The ratio of apoB to apoA-1 was most strongly related to MCE. However, for estimating differences in relative risk reduction between the treatment groups, apoB and non-HDL-C were the strongest predictors.

Interpretation. The on-treatment level of apoB/apoA-1 was the strongest predictor of MCE in the pooled patient population, whereas apoB and non-HDL-C were best able to explain the difference in outcome between treatment groups. Measurements of apoB and apoA-1 should be more widely available for routine clinical assessments.     

Effect of moxonidine on lipid subfractions in patients with hypertension

Moxonidine is centrally acting imidazoline type-1 receptor agonist that significantly lowers blood pressure and has some insulin-sensitising actions. Its effects on plasma lipid profiles are uncertain. This study examined the effects of moxonidine on detailed lipid and lipoprotein profiles in 12 patients with hypertension and type 2b Fredricksen hyperlipidaemia. Treatment with moxonidine in six patients who completed the study resulted in a 10/5 mmHg reduction in 24-h ambulatory blood pressure (p = 0.01). A significant reduction in total and low-density-lipoprotein cholesterol (LDL-C) of 10% (p = 0.04) and 18% (p = 0.03), respectively, was seen. Triglycerides were reduced non-significantly by 23%, and high-density-lipoprotein cholesterol (HDL-C) was increased by 16%. There were no significant changes in apolipoprotein (apo) A-1 and B concentrations. No significant shifts were seen in HDL-C, LDL-C, very-low-density-lipoprotein cholesterol (VLDL-C) or apolipoprotein peak positions with therapy. Analysis of area under curve for each subfraction showed that moxonidine therapy resulted in a redistribution within the apoB profile. A slight non-significant reduction in VLDL apoB was seen. There was a reduction in the dense LDL apoB peak (p = 0.02) but less in the buoyant LDL apoB peak (p = 0.17) with a countervailing increase in LDL-C in the buoyant fraction (p = 0.01). The HDL-C and apoA-1 profile showed a shift from dense HDL apoA-1 (p = 0.01) to a buoyant HDL apoA-1sub-species (p = 0.01). These changes are consistent with a tendency for moxonidine to improve atherogenic lipid and lipoprotein profiles by actions on insulin-sensitisation and possibly through a direct cholesterol-reducing effect as seen with other imidazoles.     

Hyperinsulinemia and insulin resistance in pathogenesis of atherosclerosis and ischemic heart disease

AIM: To confirm the pathogenetic relationship of hyperinsulinemia, insulin resistance, and coronary disease. MATERIAL AND METHODS: Thirty-nine coronary patients (male) were examined using lipid loading test, bicycle ergometry, coronarography, and measurements of insulin, cholesterol (CS), triglycerides (TG), very low density lipoproteins (VLDL), low density lipoproteins (LDL), high density lipoprotein (HDL) CS, apoA-1, and apoB. RESULTS: Blood levels of CS, TG, VLDL, LDL, HDL CS, apoA-1, apoB, and insulin were measured before and 3, 6, and 9 h after lipid loading in 39 coronary patients and 20 normal subjects. Coronarography showed initially high levels of insulin in coronary patients with pronounced changes. Insulin level drastically increased after insulin loading; increases in TG and apoB levels were the most pronounced, while the concentrations of HDL CS and apoA-1 decreased and did not normalize 6 h after lipid loading. CONCLUSION: The results confirmed the relationship between hyperinsulinemia, insulin resistance, and coronary disease.     

Apolipoprotein A-I, apolipoprotein B, and apolipoprotein B/apolipoprotein A-I ratio: reference intervals compared with values in different pathophysiological conditions from the FINRISK 2007 study

BackgroundIn addition to traditional measurements of serum lipid levels, apolipoprotein A-I (apoA-I), apolipoprotein B (apoB), and apoB/apoA-I ratio may add more value to risk assessment guidelines for cardiovascular disease.MethodsWe calculated reference intervals for apoA-I, apoB, and apoB/apoA-I ratio using a reference sample (n = 2828) from the FINRISK 2007 study.ResultsThe reference intervals for apoA-I were 1.1–2.0 g/l for men and 1.2–2.3 g/l for women. The corresponding reference intervals for apoB were 0.6–1.5 g/l and 0.6–1.3 g/l. The reference intervals for apoB/apoA-I ratio were 0.3–1.0 for men and 0.3–0.8 for women. Compared with the healthy reference group, obese men had the lowest ApoA-I, the highest apoB, and the highest apoB/apoA-I ratio. Men with CVD and cholesterol-lowering medication, or diabetes had lower apoB levels and apoB/apoA-1 ratio than the reference group but the opposite was true for women. The therapeutic goal for low-risk individuals for apoB was 0.9 g/l coinciding with LDL-C concentration of 3.0 mmol/l.ConclusionsReference intervals for apoA-I, apoB, and the apoB/apoA-I ratio and their cutoff values may be useful for the risk evaluation and follow-up of treatment among individuals having CVD or other metabolic disorders.     

Obesity in children, adolescents and young adults

The prevalence of obesity in Finnish children, adolescents and young adults aged three to 24 years was estimated in three surveys performed within the multicentre project, "Cardiovascular Risk in Young Finns" (1980, 1983, 1986). Obesity was defined as either body mass index (weight/height) or skinfold thickness (triceps or subscapular) or both greater than 90th percentiles of age and sex-specific reference data for white children. Its mean prevalences among 9- to 18-year old boys and girls in three surveys (95% confidence limits) were 3.6% (3.1-4.2) and 2.1% (1.7-2.6) as estimated in terms of body mass index and triceps skinfold thickness or 4.3% (3.9-4.9) and 2.6% (2.2-3.1) according to body mass index and subscapular skinfold thickness. Thus the 9- to 18-year old boys were on average more often obese than the girls, but no statistically significant changes in the prevalence of obesity were observed over the period 1980-1986. Body mass index and triceps or subscapular skinfold thicknesses vary in sensitivity as indicators of obesity.     

Anti-(apolipoprotein A-1) IgGs are associated with high levels of oxidized low-density lipoprotein in acute coronary syndrome

ApoA-1 (apolipoprotein A-1) is the main component of HDL (high-density lipoprotein) and stabilizes PON-1 (paraoxonase-1), which prevents lipid peroxidation and oxLDL (oxidized low-density lipoprotein) formation. Autoantibodies against apoA-1 [anti-(apoA-1) IgG] have been found in antiphospholipid syndrome and systemic lupus erythematosous, two diseases with an increased risk of thrombotic events, as well as in ACS (acute coronary syndrome). OxLDL levels are also elevated in these diseases. Whether anti-(apoA-1) IgGs exist in other prothrombotic conditions, such as APE (acute pulmonary embolism) and stroke, has not been studied and their potential association with oxLDL and PON-1 activity is not known. In the present study, we determined prospectively the prevalence of anti-(apoA-1) IgG in patients with ACS (n=127), APE (n=58) and stroke (n=34), and, when present, we tested their association with oxLDL levels. The prevalance of anti-(apoA-1) IgG was 11% in the ACS group, 2% in the control group and 0% in the APE and stroke groups. The ACS group had significantly higher median anti-(apoA-1) IgG titres than the other groups of patients. Patients with ACS positive for anti-(apoA-1) IgG had significantly higher median oxLDL values than those who tested negative (226.5 compared with 47.7 units/l; P<0.00001) and controls. The Spearman ranked test revealed a significant correlation between anti-(apoA-1) IgG titres and serum oxLDL levels (r=0.28, P<0.05). No association was found between PON-1 activity and oxLDL or anti-(apoA-1) IgG levels. In conclusion, anti-(apoA-1) IgG levels are positive in ACS, but not in stroke or APE. In ACS, their presence is associated with higher levels of oxLDL and is directly proportional to the serum concentration of oxLDL. These results emphasize the role of humoral autoimmunity as a mediator of inflammation and coronary atherogenesis.     

Interlaboratory variation of plasma total homocysteine measurements: results of three successive homocysteine proficiency testing surveys

BACKGROUND: Numerous studies have demonstrated that increased plasma total homocysteine (tHcy), whether measured after fasting or after a methionine load, is associated with increased risk for cardiovascular and thromboembolic diseases. However, little information is available regarding interlaboratory variation of tHcy measurements, especially at the increased tHcy concentrations observed after loading. METHODS: We conducted three Homocysteine Proficiency Testing Surveys at 6-month intervals. Sets of five plasma pools with endogenous tHcy concentrations ranging from 5 to 48 micromol/L were sent to participants. We received 11, 23, and 17 responses in the first, second, and third surveys, respectively. The following methods were used by participating laboratories: fluorescence polarization immunoassay (FPIA); HPLC with fluorescent detection (HPLC-FD), further subdivided by type of reduction/derivatization; HPLC with electrochemical detection (HPLC-ED); amino acid analyzer with ninhydrin detection; and liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). RESULTS: In surveys 1 and 2, no notable differences among the mean tHcy values obtained by the different methods performed were observed. In survey 3, tHcy values obtained by the FPIA method were significantly lower (P <0.05) at increased tHcy concentrations (34 micromol/L) compared with values obtained by HPLC-FD regardless of reduction/derivatization agents used. Our laboratory confirmed the observation that tHcy values obtained by the FPIA method differed from those obtained by HPLC-FD at increased tHcy concentrations by reanalyzing each pool 10 times by FPIA and HPLC-FD using tributylphosphine-ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (P <0.001 for tHcy >19 micro mol/L). The mean among-method variations in surveys 1, 2, and 3 were 19%, 12%, and 9.6%, respectively. When results of the three surveys were combined, the mean among-method variation on 170 samples was 13%. Within-method variation was lowest for the FPIA method (4.4%), and ranged from 11-20% for HPLC methods. CONCLUSIONS: Various degrees of imprecision and lack of correlation among tHcy methods indicate that there is a need to improve analytical precision, decrease analytical difference, and standardize tHcy measurements among laboratories.     

Factors facilitating development of degenerative aortic valvular stenosis

The aim of the study was to determine factors of risk and progress of aortal valvular calcinosis (AVC) and aortic ostium stenosis (AOS). The subjects were 85 patients with AVC (42--with aortic valvular stenosis (AVS), and 43--without AOS). The study, which included analysis of the lipid and mineral metabolism, and immunological tests, shows that potential factors of AVC are: age (p < 0. 001), osteoporosis (p < 0.03), mitral ring calcification (p = 0.047), dislipidemia (high serum level of total cholesterol, cholesterol of low density lipoproteins, and apoB, atherogenic shift of apoB/apoA-1 ratio, low level of cholesterol of high density lipoproteins (CHDLP)), disbalance between intecellular matrix synthesis and destruction (high concentration of alkaline phosphatase and its bone fraction, and accelerated deoxypyridinoline excretion), inflammation (high concentration of C-reactive protein (CRP), fibrinogen, and interleukin-6 (IL-6)). The factors of AOS were: age (p < 0.001), smoking (p < 0.001), osteoporosis (p = 0.004), AVC (p < 0.001), mitral ring calcinosis (p = 0.033), dislipidemia (high levels of cholesterol of low density and very low density lipoproteins, low concentrations of CHDLP, and apoA-1), degradation of extracellular matrix, and inflammation (high concentrations of CRP, fibrinogen, IL-6, and IL-8). Thus, atherogenic dislipidemia and mineral dysmetabolism disorder facilitate AVC. The revealed immune status changes imply the role of inflammation in the development and progress of AVS.     

An international collaborative study on standardization of apolipoproteins A-I and B. Part II. Evaluation of contributions of antisera to among-laboratory variance components

Local antisera (LA) were compared with a common interim reference antiserum (IRA) to examine the antiserum component of the among-laboratory variation in an international collaborative study with 28 laboratories evaluating a candidate international Reference Material (apo-RM) for apolipoproteins A-I (apo A-I) and B (apo B). Measurement of the relative concentration of lyophilized preparations differed by less than 1% for LA and IRA. The percentage of the total variation in measurement of the concentration of apo-RM that was contributed by antisera among laboratories was 5% and 8% for apo A-I and B, respectively. Estimated differences from overall mean concentrations for the five different immuno-methods were greater for apo B (range: +22% to -23.5%) than for apo A-I (range +14% to -14%), but were similar within a method for LA and IRA. The results indicated that antisera are not a major source of error among laboratories and, indeed, are responsible for relatively little of the total variability.     

Antimicrobial resistance in Haemophilus influenzae from England and Scotland in 1991.

Twenty-two laboratories in England and Scotland sent 2212 clinical isolates of Haemophilus influenzae to The London Hospital Medical College (LHMC) between 1 January and 31 March 1991. After confirmation of identity, the prevalence of resistance was determined and compared with results from previous similar surveys. beta-Lactamase was produced by 8.3% of non-capsulate isolates and 21% of 52 type b isolates; both figures were higher than the 6% and 18% figures recorded, respectively, in 1986. There was an increase in the prevalence of non-beta-lactamase-mediated diminished susceptibility to ampicillin (5.8%) and co-amoxiclav (6.1%) compared with 1986 (4%). Whereas fewer H. influenzae isolates were resistant to tetracycline (1.4%) or chloramphenicol (0.8%), there was an increase in resistance to trimethoprim (6.8%) and to sulphamethoxazole (16.9%) compared with 1986 (4.2% and 3.5% respectively). In addition, 95 isolates (4.3%) were resistant to both of these anti-folate antimicrobials. Six isolates (one type b from CSF) were resistant to all drugs tested, except for co-amoxiclav. Overall, the results demonstrated that changes have occurred in the last decade in England and Scotland, such that H. influenzae isolates are increasingly likely to be resistant to ampicillin, co-amoxiclav and co-trimoxazole.     

Management of antifungal susceptibility testing in Italy: comparative results of 2 nationwide surveys (1999 and 2004) in 102 Italian hospitals

The purpose of this study was to verify the standard procedures and minimum level of knowledge of Italian public laboratories involved in the management of antifungal susceptibility testing (AST). Two nationwide surveys were performed in 1999 and 2004. One hundred and two Italian hospitals located in 85 provincial capitals (82.5%) participated to these surveys. In 1999, 28 (27.5%) laboratories versus 16 (15.7%) in 2004 stated that they did not perform any susceptibility testing. Some discrepancies observed in the survey confirm that AST is difficult to be correctly managed, and that it can be performed only in very well-trained centers. The great variability of the results of MIC determination and clinical interpretation underlines the urgent need to improve knowledge about indications, method choice, and interpretative criteria for AST both for clinical microbiologists and clinicians.     

Measurement of apolipoprotein B in plasma from hyperlipidemic subjects treated with cholestyramine or placebo: differential effects of storage at -70 degrees C

Using radial immunodiffusion, we measured apolipoprotein B (apoB) concentrations in fresh plasma from 216 hyperlipidemic male subjects and in aliquots of the same plasma stored at -70 degrees C for 22 months. At the time of sampling, 112 were being treated with cholestyramine, the rest with a placebo. ApoB concentrations in the stored samples were significantly and positively correlated with apoB concentrations in the fresh samples (r = 0.84, P less than 0.001), the mean (and SD) being 1680 (320) mg/L and 1570 (320) mg/L, respectively. This 6.5% decrease in the stored samples was statistically significant (P = 0.0005), but there was no significant correlation between the decrease in apoB values in the stored samples and plasma triglyceride concentrations measured in the fresh samples. The correlation between the two apoB analyses was greater in the cholestyramine-treated group (r = 0.90) than in subjects treated with the placebo (r = 0.75).     

National survey on the pre-analytical variability in a representative cohort of Italian laboratories.

BACKGROUND: Owing to remarkable advances in automation, laboratory technology and informatics, the pre-analytical phase has become the major source of variability in laboratory testing. The present survey investigated the development of several pre-analytical processes within a representative cohort of Italian clinical laboratories. METHODS: A seven-point questionnaire was designed to investigate the following issues: 1a) the mean outpatient waiting time before check-in and 1b) the mean time from check-in to sample collection; 2) the mean time from sample collection to analysis; 3) the type of specimen collected for clinical chemistry testing; 4) the degree of pre-analytical automation; 5a) the number of samples shipped to other laboratories and 5b) the availability of standardised protocols for transportation; 6) the conditions for specimen storage; and 7) the availability and type of guidelines for management of unsuitable specimens. The questionnaire was administered to 150 laboratory specialists attending the SIMEL (Italian Society of Laboratory Medicine) National Meeting in June 2006. RESULTS: 107 questionnaires (71.3%) were returned. Data analysis revealed a high degree of variability among laboratories for the time required for check-in, outpatient sampling, sample transportation to the referral laboratory and analysis upon the arrival. Only 31% of laboratories have automated some pre-analytical steps. Of the 87% of laboratories that ship specimens to other facilities without sample preparation, 19% have no standardised protocol for transportation. For conventional clinical chemistry testing, 74% of the laboratories use serum evacuated tubes (59% with and 15% without serum separator), whereas the remaining 26% use lithium-heparin evacuated tubes (11% with and 15% without plasma separator). The storage period and conditions for rerun/retest vary widely. Only 63% of laboratories have a codified procedure for the management of unsuitable specimens, which are recognised by visual inspection (69%) or automatic detection (29%). Only 56% of the laboratories have standardised procedures for the management of unsuitable specimens, which vary widely on a local basis. CONCLUSIONS: The survey highlights broad heterogeneity in several pre-analytical processes among Italian laboratories. The lack of reliable guidelines encompassing evidence-based practice is a major problem for the standardisation of this crucial part of the testing process and represents a major challenge for laboratory medicine in the 2000s.     

非诺贝特治疗高脂血症40例疗效观察

目的：观察非诺贝特对高脂血症的疗效。方法：对４０例高脂血症患者使用非诺贝特，每日３００ｍｇ，疗程６个月；治疗前后检测血清总胆固醇（ＴＣ）、甘油三酯（ＴＧ）、低密度脂蛋白胆固醇（ＬＤＬＣ）、高密度脂蛋白胆固醇（ＨＤＬＣ）和载脂蛋白Ａ１（ａｐｏＡ１）、载脂蛋白Ｂ（ａｐｏＢ）等。结果：ＴＧ平均降低了４５．２％，ＴＣ平均降低了２０．５％，ＨＤＬＣ平均上升了１５．４％，ＬＤＬＣ平均降低了２５．５％，ａｐｏＡ１平均上升了２．０％，ａｐｏＢ平均下降了３０．０％。结论：非诺贝特具有降低ＴＧ、ＴＣ、ＬＤＬＣ、ａｐｏＢ和升高ＨＤＬＣ、ａｐｏＡ１作用，从而可减少冠状动脉粥样硬化性心脏病的发病率和病死率     

Reference intervals based on hospitalized 'healthy' patients and medical students in relation to analytical bias for serum potassium.

The reliability of reference intervals for measurements of serum (S)-potassium in Danish hospital laboratories was investigated (i) by estimation of reference interval based on two different, healthy subpopulations and (ii) by comparison of reference intervals for S-potassium with analytical bias in each of 52 Danish laboratories. (i) The reference values from 227 hospitalized 'healthy' patients were obtained during the period 1979 to 1987 from the first-drawn serum specimen from the hospitalized patients, who were later discharged from the hospital without a diagnosis. The estimated 0.95 reference interval was 3.34 to 4.52 mmol l-1. The other reference sample group consisted of 314 medical students from whom blood was collected in the period from 1983 to 1987. Here the estimated reference interval was from 3.44 to 4.53 mmol l-1. The concentration values from both reference sample groups were corrected for analytical bias (+0.05 mmol l-1). (ii) The 52 Danish laboratories revealed a considerable variability in reference intervals which, regarding the lower reference limit, ranged from 3.2 to 3.7 mmol l-1 in strong contrast to the analytical bias (ranging from -0.08 to +0.15 mmol l-1) in 50 laboratories (two outliers). There was no relationship between lower reference limit and analytical bias in the individual laboratories. It is concluded that analytical performance allows for more uniform (even common) reference intervals throughout the Danish and perhaps Nordic hospital laboratories.     

Nomenclature of Reagents

The reliability of reference intervals for measurements of serum (S)-potassium in Danish hospital laboratories was investigated (i) by estimation of reference interval based on two different, healthy subpopulations and (ii) by comparison of reference intervals for S-potassium with analytical bias in each of 52 Danish laboratories.

(i) The reference values from 227 hospitalized ‘healthy’ patients were obtained during the period 1979 to 1987 from the first-drawn serum specimen from the hospitalized patients, who were later discharged from the hospital without a diagnosis. The estimated 0.95 reference interval was 3.34 to 4.52 mmol l^-1. The other reference sample group consisted of 314 medical students from whom blood was collected in the period from 1983 to 1987. Here the estimated reference interval was from 3.44 to 4.53 mmol l^-1. The concentration values from both reference sample groups were corrected for analytical bias (+0–05 mmol l^-1).

(ii) The 52 Danish laboratories revealed a considerable variability in reference intervals which, regarding the lower reference limit, ranged from 3.2 to 3.7 mmol l^-1 in strong contrast to the analytical bias (ranging from-0.08 to +0.15 mmol l^-1) in 50 laboratories (two outliers). There was no relationship between lower reference limit and analytical bias in the individual laboratories. It is concluded that analytical performance allows for more uniform (even common) reference intervals throughout the Danish and perhaps Nordic hospital laboratories.