The Nordic Reference Interval Project 2000: recommended reference intervals for 25 common biochemical properties

Each of 102 Nordic routine clinical biochemistry laboratories collected blood samples from at least 25 healthy reference individuals evenly distributed for gender and age, and analysed 25 of the most commonly requested serum/plasma components from each reference individual. A reference material (control) consisting of a fresh frozen liquid pool of serum with values traceable to reference methods (used as the project "calibrator" for non-enzymes to correct reference values) was analysed together with other serum pool controls in the same series as the project samples. Analytical data, method data and data describing the reference individuals were submitted to a central database for evaluation and calculation of reference intervals intended for common use in the Nordic countries. In parallel to the main project, measurements of commonly requested haematology properties on EDTA samples were also carried out, mainly by laboratories in Finland and Sweden. Aliquots from reference samples were submitted to storage in a central bio-bank for future establishment of reference intervals for other properties. The 25 components were, in alphabetical order: alanine transaminase, albumin, alkaline phosphatase, amylase, amylase pancreatic, aspartate transaminase, bilirubins, calcium, carbamide, cholesterol, creatine kinase, creatininium, gamma-glutamyltransferase, glucose, HDL-cholesterol, iron, iron binding capacity, lactate dehydrogenase, magnesium, phosphate, potassium, protein, sodium, triglyceride and urate.

Reference intervals for serum creatinine concentrations: assessment of available data for global application

BACKGROUND

Reference intervals for serum creatinine remain relevant despite the current emphasis on the use of the estimated glomerular filtration rate for assessing renal function. Many studies on creatinine reference values have been published in the last 20 years. Using criteria derived from published IFCC documents, we sought to identify universally applicable reference intervals for creatinine via a systematic review of the literature.

METHODS

Studies were selected for inclusion in the systematic review only if the following criteria were met: (a) reference individuals were selected using an "a priori" selection scheme, (b) preanalytical conditions were adequately described; (c) traceability of the produced results to the isotope dilution-mass spectrometry (IDMS) reference method was demonstrated experimentally, and (d) the collected data received adequate statistical treatment.

RESULTS

Of 37 reports dealing specifically with serum creatinine reference values, only 1 report with pediatric data and 5 reports with adult data met these criteria. The primary reason for exclusion of most papers was an inadequate demonstration of measurement traceability. Based on the data of the selected studies, we have collated recommended reference intervals for white adults and children.

CONCLUSION

Laboratories using methods producing traceable results to IDMS can apply the selected reference intervals for serum creatinine in evaluating white individuals.

Software for illustrative presentation of basic clinical characteristics of laboratory tests--GraphROC for Windows

GraphROC for Windows is a program for clinical test evaluation. It was designed for the handling of large datasets obtained from clinical laboratory databases. In the user interface, graphical and numerical presentations are combined. For simplicity, numerical data is not shown unless requested. Relevant numbers can be "picked up" from the graph by simple mouse operations. Reference distributions can be displayed by using automatically optimized bin widths. Any percentile of the distribution with corresponding confidence limits can be chosen for display. In sensitivity-specificity analysis, both illness- and health-related distributions are shown in the same graph. The following data for any cutoff limit can be shown in a separate click window: clinical sensitivity and specificity with corresponding confidence limits, positive and negative likelihood ratios, positive and negative predictive values and efficiency. Predictive values and clinical efficiency of the cutoff limit can be updated for any prior probability of disease. Receiver Operating Characteristics (ROC) curves can be generated and combined into the same graph for comparison of several different tests. The area under the curve with corresponding confidence interval is calculated for each ROC curve. Numerical results of analyses and graphs can be printed or exported to other Microsoft Windows programs. GraphROC for Windows also employs a new method, developed by us, for the indirect estimation of health-related limits and change limits from mixed distributions of clinical laboratory data.

A multicentre study of reference intervals for haemoglobin, basic blood cell counts and erythrocyte indices in the adult population of the Nordic countries

Eight haematological quantities were measured in EDTA anticoagulated venous blood specimens collected from 1826 healthy male and female individuals between 18 and 90 years of age in the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden). The samples, collected between November 1999 and November 2001 as part of the Nordic Reference Interval Project (NORIP), were analysed on 12 different types of modern automated haematology instruments currently in use among the 60 laboratories participating in the study. Non-parametric reference intervals (between 2.5 and 97.5 percentiles) have been calculated for B-Haemoglobin (females 117-153 g/L, males 134-170 g/L), B-Erythrocytes (females 3.94-5.16 x 10(12)/L, males 4.25-5.71 x 10(12)/L), B-EVF (females 0.348-0.459, males 0.395-0.500), B-MCV (82-98 fL), Erc-MCH (27.1-33.3 pg), Erc-MCHC (317-357 g/L), B-Trc (females 165-387 x 10(9)/L, males 145 x 348 x 10(9)/L) and B-Lkc (3.5-8.8 x 10(9)/L). Partitioning of data according to age and gender was done according to a standardized procedure. For most variables the calculated reference intervals corresponded well with older and less well-defined reference intervals. The mean concentration of B-Haemoglobin increased by 0.08 g/L per year of age in women, and decreased by 0.1 g/L per year of age in men. B-Haemoglobin increased with body mass index in both men and women. Smoking increased the mean of B-Lkc by 1.1 x 10(9)/L and regular use of alcohol increased the mean of B-MCV by 0.8 fL. The influence of these factors was small overall and did not promote specific reference intervals.

A certified plasmid reference material for the standardisation of BCR-ABL1 mRNA quantification by real-time quantitative PCR

Serial quantification of BCR–ABL1 mRNA is an important therapeutic indicator in chronic myeloid leukaemia, but there is a substantial variation in results reported by different laboratories. To improve comparability, an internationally accepted plasmid certified reference material (CRM) was developed according to ISO Guide 34:2009. Fragments of BCR–ABL1 (e14a2 mRNA fusion), BCR and GUSB transcripts were amplified and cloned into pUC18 to yield plasmid pIRMM0099. Six different linearised plasmid solutions were produced with the following copy number concentrations, assigned by digital PCR, and expanded uncertainties: 1.08±0.13 × 10⁶, 1.08±0.11 × 10⁵, 1.03±0.10 × 10⁴, 1.02±0.09 × 10³, 1.04±0.10 × 10² and 10.0±1.5 copies/μl. The certification of the material for the number of specific DNA fragments per plasmid, copy number concentration of the plasmid solutions and the assessment of inter-unit heterogeneity and stability were performed according to ISO Guide 35:2006. Two suitability studies performed by 63 BCR–ABL1 testing laboratories demonstrated that this set of 6 plasmid CRMs can help to standardise a number of measured transcripts of e14a2 BCR–ABL1 and three control genes (ABL1, BCR and GUSB). The set of six plasmid CRMs is distributed worldwide by the Institute for Reference Materials and Measurements (Belgium) and its authorised distributors (https://ec.europa.eu/jrc/en/reference-materials/catalogue/; CRM code ERM-AD623a-f).

The occurrence of dominant spinocerebellar ataxias among 251 Finnish ataxia patients and the role of predisposing large normal alleles in a genetically isolated population

OBJECTIVES

Frequency and distribution of dominant ataxias caused by dynamic mutations may vary in different populations, which has been explained on the basis of relative frequency of predisposing normal alleles. The aim of the study was to evaluate the occurrence of spinocerebellar ataxias (SCAs) and dentatorubral-pallidoluysian atrophy (DRPLA) in Finland, and to investigate the role of predisposing normal alleles in a genetically homogenous population.

MATERIAL AND METHODS

Mutation analyses for SCA1, 2, 3, 6, 7, 8, 10, 12, 17, and DRPLA and frataxin genes were performed for 251 unrelated Finnish patients who presented with progressive ataxia disorder.

RESULTS

Expansions of SCA1, SCA2, SCA6, SCA7, SCA8, and SCA17 genes were detected in 2, 1, 1, 7, 22, and 1 patients, respectively. Altogether, 39 and 7% of dominant and sporadic SCA patients, respectively, harboured expansions at some of the investigated loci. Normal variation, collected from 477 to 502 chromosomes at each disease loci, revealed that Finns were different from the Japanese but largely similar to other Caucasians.

CONCLUSIONS

Lack of SCA3 and excess of SCA8 are characteristic to the Finnish population. Homozygosity for the SCA8 expansion increases penetrance. Frequencies of large normal alleles at the SCA loci predict poorly prevalence of the respective diseases in Finland. Prioritization in DNA testing, based on ethnic origin and geographical location, is recommendable in Finland, and analogous approach may be applied to other countries as well.

Reference intervals developed from data for hospitalized patients: computerized method based on combination of laboratory and diagnostic data

We utilized the databases of a hospital information system to select for determination of reference values various individual hospitalized patients on the basis of their diagnoses at discharge. The nonparametric 2.5-97.5% "health-related" reference intervals were calculated for hemoglobin concentration, mean corpuscular volume (MCV), and erythrocyte count for both sexes. After excluding patients with diseases possibly affecting erythrocyte variables, we obtained a final group of 1786 women and 1450 men, ages 20-65 years, who were studied in age groups of 20-30, 30-45, 45-55, and 55-65 years. The upper reference limits of the MCV results obtained from hospitalized patients were higher than those produced conventionally from healthy individuals, as would be intuitively suggested by clinical experience. This method, based on selection by diagnosis, could be applicable to various analytes measured in hospital laboratories, provided sufficient data are available as databases.

Outcome of Traumatic Brain Injury after Three Decades— Relationship to ApoE Genotype

Significant traumatic brain injury (TBI) is nearly always associated with cognitive deficits, but in a highly variable manner. Apolipoprotein E (ApoE) plays a pivotal role in CNS response to injury. To examine the association of ApoE genotype with long-term outcome in TBI patients, we determined the ApoE genotype from 61 TBI patients who had been injured over three decades earlier. All patients had been studied neuropsychologically after their injuries. The long-term outcome was evaluated with repeated neuropsychological testing and by applying various measures of everyday functioning and quality of life. After three decades, TBI patients with the ApoE epsilon4 allele showed significantly poorer general cognitive level than those without this allele. This decline was wholly accounted for by a subgroup of these patients who had developed incident or clinical dementia, while the majority of the ApoE epsilon4 positive patients showed no decline at all. The other outcome measures describing vocational, physical, or subjective symptom outcome did not show significant relationships to the ApoE genotype. A portion of the TBI patients with the ApoE epsilon4 allele seem to be at risk of long-term cognitive decline.

APOE- 4 predicts dementia but not other psychiatric disorders after traumatic brain injury

The authors studied the association between APOE-epsilon4 genotype and axis I and II psychiatric disorders an average of 30 years after traumatic brain injury. Sixty patients were dichotomized into subjects with and without APOE-epsilon4 allele. Dementia and subclinical dementia were significantly more common with the presence of APOE-epsilon4. The occurrence of other psychiatric disorders did not differ between patients with and without APOE-epsilon4 allele.

Chronic myeloid leukemia patients in prolonged remission following interferon-α monotherapy have distinct cytokine and oligoclonal lymphocyte profile

Before the era of tyrosine kinase inhibitors (TKIs), interferon-alpha (IFN-α) was the treatment of choice in chronic myeloid leukemia (CML). Curiously, some IFN-α treated patients were able to discontinue therapy without disease progression. The aim of this project was to study the immunomodulatory effects of IFN-α in CML patients in prolonged remission and isolate biological markers predicting response. Due to rarity of patients on IFN-α monotherapy, a relatively small cohort of patients still on treatment (IFN-ON, n = 10, median therapy duration 11.8 years) or had discontinued IFN-α therapy but remained in remission for >2 years (IFN-OFF, n = 9) were studied. The lymphocyte immunophenotype was analyzed with a comprehensive flow cytometry panel and plasma cytokine levels were measured with multiplex bead-based assay. In addition, the clonality status of different lymphocyte subpopulations was analyzed by TCR γ/δ rearrangement assay. Median NK-cell absolute number and proportion from lymphocytes in blood was higher in IFN-OFF patients as compared to IFN-ON patients or controls (0.42, 0.19, 0.21×10⁹/L; 26%, 12%, 11%, respectively, p<0.001). The proportion of CD8+ T-cells was significantly increased in both patient groups and a larger proportion of T-cells expressed CD45RO. Most (95%) patients had significant numbers of oligoclonal lymphocytes characterized by T-cell receptor γ/δ rearrangements. Strikingly, in the majority of patients (79%) a distinct clonal Vγ9 gene rearrangement was observed residing in γδ⁺ T-cell population. Similar unique clonality pattern was not observed in TKI treated CML patients. Plasma eotaxin and MCP-1 cytokines were significantly increased in IFN-OFF patients. Despite the limited number of patients, our data indicates that IFN-α treated CML patients in remission have increased numbers of NK-cells and clonal γδ⁺ T-cells and a unique plasma cytokine profile. These factors may relate to anti-leukemic effects of IFN-α in this specific group of patients and account for prolonged therapy responses even after drug discontinuation.

Depth of response assessed by quantitative ASO-PCR predicts the outcome after stem cell transplantation in multiple myeloma

Achievement of complete response (CR) is a new goal of therapy for multiple myeloma (MM). By sensitive methods, the depth of response can be measured even among the patients in CR. We used a sensitive real-time quantitative polymerase chain reaction by allele-specific primers (qASO-PCR) to assess the level of minimal residual disease (MRD) in bone marrow of 37 patients with myeloma who had achieved CR/near-to-CR after autologous or allogeneic stem cell transplantation (SCT). Allele-specific primers could be successfully designed for 86% of patients. Three to six months after autotransplantation, the PCR target was not detectable in 53% of patients (16/30 patients), and the respective figure after allotransplantation was 71% (5/7 patients); the median sensitivity of PCR assay was <0.002%. The proportion of patients without detectable PCR target was 22% of all autotransplanted patients. A threshold level of 0.01% in the qASO-PCR assay 3-6 months after SCT was found to be a useful cut-off limit to divide the patients into two prognostic groups: MRD low/negative vs. MRD high. Low/negative MRD after SCT was a significant predictive factor for the prolongation of progression free (70 vs. 19 months; P = 0.003) and suggestively also for overall survival. We conclude that not only CR but also its depth is important for the long-term outcome in MM.

Regression-based reference limits: determination of sufficient sample size

Regression analysis is the method of choice for the production of covariate-dependent reference limits. There are currently no recommendations on what sample size should be used when regression-based reference limits and confidence intervals are calculated. In this study we used Monte Carlo simulation to study a reference sample group of 374 age-dependent hemoglobin values. From this sample, 5000 random subsamples, with replacement, were constructed with 10–220 observations per sample. Regression analysis was used to estimate age-dependent 95% reference intervals for hemoglobin concentrations and erythrocyte counts. The maximum difference between mean values of the root mean square error and original values for hemoglobin was 0.05 g/L when the sample size was ≥60. The parameter estimators and width of reference intervals changed negligibly from the values calculated from the original sample regardless of what sample size was used. SDs and CVs for these factors changed rapidly up to a sample size of 30; after that changes were smaller. The largest and smallest absolute differences in root mean square error and width of reference interval between sample values and values calculated from the original sample were also evaluated. As expected, differences were largest in small sample sizes, and as sample size increased differences decreased. To obtain appropriate reference limits and confidence intervals, we propose the following scheme: (a) check whether the assumptions of regression analysis can be fulfilled with/without transformation of data; (b) check that the value of v, which describes how the covariate value is situated in relation to both the mean value and the spread of the covariate values, does not exceed 0.1 at minimum and maximum covariate positions; and (c) if steps 1 and 2 can be accepted, the reference limits with confidence intervals can be produced by regression analysis, and the minimum acceptable sample size will be ∼70.

Hippocampal volume, brain atrophy, and APOE genotype after traumatic brain injury

OBJECTIVE

To examine the association between hippocampal volumes, general brain atrophy, and apolipoprotein E (APOE) polymorphism in patients with a remote traumatic brain injury (TBI).

METHODS

MRI-based volumetric analyses of the hippocampus and lateral ventricles were performed in 58 patients with TBI of varying severity on average 31.3 years after the trauma. The APOE genotype was determined using standard methods and correlated with the MRI volumetric measurements.

RESULTS

Hippocampal or lateral ventricle volumes did not differ significantly in those patients with the APOE-epsilon4 allele (APOE4) vs those without this allele.

CONCLUSIONS

The APOE-epsilon4 allele was not associated with the development of hippocampal or ventricular atrophy after traumatic brain injury. If the APOE-epsilon4 allele is associated with an unfavorable outcome after traumatic brain injury as proposed, this association may involve mechanisms other than those responsible for the development of brain atrophy.

Reference individuals, blood collection, treatment of samples and descriptive data from the questionnaire in the Nordic Reference Interval Project 2000

The rules for recruitment of reference individuals, inclusion and preparation of individuals, blood collection, treatment of samples (and control materials) and analysis at the 102 medical laboratories attending the Nordic Reference Interval Project (NORIP) are given as well as the rules for central exclusion of reference individuals. The individuals (18-91-year-olds) should be evenly distributed on age and gender groups. The 3002 reference individuals who contributed at least one reference value to the finally suggested reference intervals were characterized using the information in the questionnaire. Gender, age and country are the main entries in the tables. Other variables in the cross-tables or figure are height, weight, body mass index, ethnic origin, heredity for diabetes, chronic disease, oestrogens or oral contraceptives, other medication, hard physical activity, previous blood donations, smoking habits, use of alcohol, hours since last meal and time of blood collection (hour, day of week, month, year). The Danes had the highest alcohol consumption and the Icelanders had the highest body mass index. The information in this article may interest potential users of the Nordic Reference Interval Project bio-bank and database (NOBIDA) in which serum, Li-heparin plasma and EDTA buffy coat from the mentioned individuals are stored below -80 degrees C.

Comparative analysis of minimal residual disease detection by multiparameter flow cytometry and enhanced ASO RQ-PCR in multiple myeloma

Multiparameter flow cytometry (MFC) and allele-specific oligonucleotide real-time quantitative PCR (ASO RQ-PCR) are the two most sensitive methods to detect minimal residual disease (MRD) in multiple myeloma (MM). We compared these methods in 129 paired post-therapy samples from 22 unselected, consecutive MM patients in complete/near complete remission. Appropriate immunophenotypic and ASO RQ-PCR-MRD targets could be detected and MRD analyses constructed for all patients. The high PCR coverage could be achieved by gradual widening of the primer sets used for clonality detection. In addition, for 13 (55%) of the patients, reverse orientation of the ASO primer and individual design of the TaqMan probe improved the sensitivity and specificity of ASO RQ-PCR analysis. A significant nonlinear correlation prevailed between MFC-MRD and PCR-MRD when both were positive. Discordance between the methods was found in 32 (35%) paired samples, which were negative by MFC-MRD, but positive by ASO RQ-PCR. The findings suggest that with the described technique, ASO RQ-PCR can be constructed for all patients with MM. ASO RQ-PCR is slightly more sensitive in MRD detection than 6-10-color flow cytometry. Owing to technical demands ASO RQ-PCR could be reserved for patients in immunophenotypic remission, especially in efficacy comparisons between different drugs and treatment modalities.

Characterization of a reference material for BCR-ABL (M-BCR) mRNA quantitation by real-time amplification assays: towards new standards for gene expression measurements

Monitoring of BCR-ABL transcripts has become established practice in the management of chronic myeloid leukemia. However, nucleic acid amplification techniques are prone to variations which limit the reliability of real-time quantitative PCR (RQ-PCR) for clinical decision making, highlighting the need for standardization of assays and reporting of minimal residual disease (MRD) data. We evaluated a lyophilized preparation of a leukemic cell line (K562) as a potential quality control reagent. This was found to be relatively stable, yielding comparable respective levels of ABL, GUS and BCR-ABL transcripts as determined by RQ-PCR before and after accelerated degradation experiments as well as following 5 years storage at -20 degrees C. Vials of freeze-dried cells were sent at ambient temperature to 22 laboratories on four continents, with RQ-PCR analyses detecting BCR-ABL transcripts at levels comparable to those observed in primary patient samples. Our results suggest that freeze-dried cells can be used as quality control reagents with a range of analytical instrumentations and could enable the development of urgently needed international standards simulating clinically relevant levels of MRD.

Wilms tumour gene 1 overexpression in bone marrow as a marker for minimal residual disease in acute myeloid leukaemia

OBJECTIVES

Wilms tumour gene 1 (WT1) is overexpressed in leucocytes of most acute myeloid leukaemia (AML) patients. However, the clinical relevance of WT1 gene expression as minimal residual disease (MRD) marker in AML has been questioned.

METHODS

We determined the expression of WT1 gene in bone marrow (BM) mononuclear cells of 100 AML patients at diagnosis and compared it with other MRD markers during follow up in 16 patients using quantitative reverse transcription-polymerase chain reaction.

RESULTS

The median WT1 gene expression was 9.7% of K562 cell line WT1 expression (lower quartile 1.5%, upper quartile 29.9%, n = 100) at diagnosis and, 0.053% (lower quartile 0.022%, upper quartile 0.125%, n = 87) in molecular or immunophenotypic remission. Median WT1 expression in control BM was 0.029% (lower quartile 0.013%, upper quartile 0.061%, n = 22). The upper 99% percentile of remission samples was 0.3%, which was regarded as the cut-off of increased WT1 gene expression in AML and was exceeded in 87% of all AML patients at diagnosis. WT1 and the other MRD markers showed only minor differences in profiles during follow-up. WT1 expression at diagnosis with median value 9.7% as the cut-off level or as a continuous variable had no prognostic significance for 2-yr survival.

CONCLUSIONS

The sensitivity of WT1 as a MRD marker was low due to the relatively high background WT1 gene expression in BM cells at remission and in subjects without haematological malignancies. Therefore, WT1 gene expression analysis would be beneficial only in those patients who do not have a more specific and sensitive MRD marker.

Method for determining reference changes from patients' serial data: example of cardiac enzymes

Changes between serial laboratory test results can be significant, even if none of the individual results exceeds the reference interval. We developed a statistical method for the calculation of reference change limits from routine patients' data for situations in which the majority of the patients can be considered suitable reference subjects. The method was applied to cardiac enzyme data [creatine kinase (CK; EC 2.7.3.2), creatine kinase isoenzyme MB (CK-2), lactate dehydrogenase (LD; EC 1.1.1.28), and lactate dehydrogenase isoenzyme 1 (LD-1)] from 2029 consecutive patients. We used hospital discharge diagnoses to exclude patients with the diagnosis of myocardial infarction or myocarditis, but we also studied the characteristics of the method on unselected patients' data. The reference change limits derived from the diagnosis-selected patient group were as follows (U/L, activity measurements in serum at 37 degrees C according to Scandinavian recommendations): CK from -39 to 27, CK-2 from -8 to 7, LD from -86 to 85, and LD-1 from -19 to 15. Similar limits were obtained by conventional statistical methods from a group of 29 hospitalized patients with no myocardial symptoms. Our results suggest that it is possible to produce clinically applicable reference change limits from routine data.

Measurable residual disease assessment by qPCR in peripheral blood is an informative tool for disease surveillance in childhood acute myeloid leukaemia

Serial assessments of measurable (or minimal) residual disease (MRD) by qPCR may identify nascent relapse in children with acute myeloid leukaemia (AML) and enable pre-emptive therapy. We investigated the kinetics and prognostic impact of recurrent fusion transcripts (RUNX1-RUNX1T1, CBFB-MYH11, KMT2A-MLLT3 or KMT2A-ELL) in 774 post-induction samples from bone marrow (BM, 347) and peripheral blood (PB, 427) from 75 children with AML. BM MRD persistence during consolidation did not increase the risk of relapse, and MRD at therapy completion did not correlate to outcome (HR = 0·64/MRD log reduction (CI: 0·32-1·26), P = 0·19). In contrast, 8/8 patients with detectable MRD in PB after first consolidation relapsed. Persistence (n = 4) and shifting from negative to positive (n = 10) in PB during follow-up predicted relapse in 14/14 patients. All 253 PB samples collected during follow-up from 36 patients in continuous complete remission were MRD negative. In core-binding factor AML, persistent low-level MRD positivity in BM during follow-up was frequent but an increment to above 5 × 10^-4 heralded subsequent haematological relapse in 12/12 patients. We demonstrate that MRD monitoring in PB after induction therapy is highly informative and propose an MRD increment above 5 × 10^-4 in PB and BM as a definition of molecular relapse since it always leads to haematological relapse.

Antimicrobial therapy of septicemic patients in intensive care units before and after blood culture reporting

68 cases of positive blood cultures from 54 intensive care unit (ICU) patients were analyzed retrospectively. The empiric antimicrobial therapy was correct in 65% of the cases as judged by the species and sensitivity of the blood culture isolate. After initial Gram-staining results were known, coverage increased to 77%. After the final blood culture results the coverage was still only 81%. The bacteremia-related mortality was 13%. Although there was no significant difference between the occurrence of bacteremia-related and non-bacteremia-related deaths either in patients with correct or non-optimal empiric treatment, this study emphasizes the need for better utilization of culture reporting. A considerable part of the final blood culture results went unnoticed by the ICU physicians which stresses the importance of good communication between the laboratory and wards.

Reference Intervals for 24-h Urinary Normetanephrine, Metanephrine, and 3-Methoxy-4-Hydroxymandelic Acid in Hypertensive Patients

The urinary excretion of normetanephrine, metanephrine, and 3-methoxy-4-hydroxymandelic acid was quantified by HPLC in hypertensive patients who were being routinely investigated for the exclusion of pheochromocytoma. The data were used to calculate reference intervals for these analytes. Age- and sex-specific 95% reference intervals for 24-h urinary excretion were as follows (mumol/24 h): normetanephrine in men ages 16-35 years (n = 17) 0.7-3.4, in men older than 35 years (n = 121) 0.8-5.1, in women ages 16-35 years (n = 41) 0.5-2.1, and in women older than 35 years (n = 144) 0.6-3.3 mumol/24 h; metanephrine in men (n = 138) 0.3-2.0, and in women (n = 185) 0.2-1.3; and 3-methoxy-4-hydroxymandelic acid in men (n = 142) 10-54, and in women (n = 184) 9-38. Normetanephrine or metanephrine excretion rates or both exceeded the proposed reference intervals in seven of the eight patients with pheochromocytoma. Determination of 3-methoxy-4-hydroxymandelic acid excretion did not yield any additional diagnostic information.