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O Blaabjerg

Publications and source records attributed to O Blaabjerg.

At least 37 records · Page 2Linked to original sources
PubMed1993

Analytical bias by contamination from hemolysis in determination of serum lactate dehydrogenase isoenzyme 1 in patients with testis germ cell tumors.

We investigated the impact of correction for contamination from hemolysis on serum lactate dehydrogenase isoenzyme 1 (S-LD-1) determinations. A study of hemolysates from 7 control patients showed a mean correction factor for the contamination of 0.1 U/L S-LD-1 for each 1 mg/L serum hemoglobin (S-Hb). S-LD-1 in a series of blood samples from 44 patients (EJC 1992;28:410-5) would decrease median 24 U/L (range 8-70 U/L) if the measurements were corrected with this factor. So we advice to correct S-LD-1 determinations for the contamination with a common correction based on the S-Hb concentrations in the samples.

Chemistry Techniques, Analytical↗
PubMed1993

A Nordic reference serum suitable for use as trueness control in the clinical routine laboratory.

The described reference serum is characterized by: liquid human serum at "normal" level stored in frozen state at -80 degrees C; minimum damage of proteins; aseptic preparation; cryoprecipitate and excess fibrin removed; serum cleared by ultracentrifugation; pH at 7.2-7.6; available in sealed glass ampoules with inert gas (one ml serum in each); specified components among most frequently analyzed analytes; homogeneity assured and stability monitored; produced under strict rules for good manufacturing practices (GMP). The assigned values are traceable to reference measurement procedures and reference materials of highest achievable metrological level; according to the present proposal the maximum allowable uncertainty of the assigned value is based on biological variation (shared common reference intervals); the uncertainty should ideally not exceed 1/5 of the maximum allowable bias of results obtained on patients samples (even 1/2 would theoretically be acceptable and, for a practical guide approximately < 1% may suffice). The present document provides some guidance of how the reference serum could be established in practice. The document also indicates the use of the material and further extension of the concept. The present work is done as a NORDKEM project.

Blood Chemical Analysis↗
PubMed1993

A model for quality achievement--the NORDKEM protein project.

UNLABELLED: The Nordic protein project demonstrates a model for the process of achieving analytical quality. GOAL: based on use of common reference intervals leading to the quality specifications. Creation of quality: through common high quality calibrator (with IFCC-values) (external factor) and individual trouble-shooting and guidelines (internal factor). Control of quality: with specially designed set of control samples and problem-related evaluation of control data. Establishing common reference intervals: through associated projects.

Blood Proteins↗
PubMed1993

Appropriate sera for calibration and control of specific protein assays.

An ultracentrifugation technique is described which makes it possible to prepare protein calibrators and control sera which (i) are stable (more than 8 years documented for nine proteins), (ii) are clear (remains clear for more than 8 years at -80 degrees C), (iii) contain genuine proteins (documented electrophoretically and immunologically), and (iv) are reproducible to prepare (collection and preparation).

Blood↗
PubMed1992

Serum lactate dehydrogenase isoenzyme 1 activity in patients with testicular germ cell tumors correlates with the total number of copies of the short arm of chromosome 12 in the tumor.

The aim of our study was to assess the relationship between the serum lactate dehydrogenase isoenzyme 1 (S-LDH-1) activity in patients with testicular germ cell tumors and the number of copies of the short arm of chromosome 12 (12p) present in tumor. Twenty-seven adult patients with measurable tumor lesions were studied. Twenty-five had three or more copies of chromosome 12 per cell in the tumors. Nineteen had one or more copies of a specific chromosomal abnormality, an isochromosome of the short arm of chromosome 12, i(12p). Fourteen had increased S-LDH-1 levels. S-LDH-1 activity correlated significantly with the product of total tumor volume and the total number of copies of the short arm of chromosome 12 present per cell (total tumor 12p). We conclude that the total number of copies of the short arm of chromosome 12 in the tumors is most probably a factor contributing to the LDH-1 activity released from the tumors.

Adult↗
PubMed1992

Serum lactate dehydrogenase isoenzyme 1 and tumour volume are indicators of response to treatment and predictors of prognosis in metastatic testicular germ cell tumours.

44 patients with metastatic testicular germ cell tumours treated with cisplatin-based chemotherapy were evaluated for prognostic implications of clinical characteristics. 22 obtained complete remission by the initial chemotherapy, and 30 are disease-free. S-LDH-1 had an overall predictive value regarding the response of 80%, S-LDH of 64%, S-AFP of 62%, and S-hCG of 62%. In multivariate analysis regarding response, only tumour volume classified according to the Royal Marsden system (P = 0.0036) and S-LDH-1 (P = 0.0069) yielded information. Regarding survival, S-LDH-1 (P = 0.0141) and an estimate of total tumour mass (P = 0.0171) had most impact with additional information from S-hCG only (P = 0.0536). We conclude that S-LDH-1 may be used as a tumour marker in addition to S-hCG and S-AFP in patients with metastatic testicular germ cell tumour.

Adolescent↗
PubMed1991

Screening for haemochromatosis: influence of analytical imprecision, diagnostic limit and prevalence on test validity.

Serum ferritin (S-ferritin) and the saturation of transferrin iron-binding capacity (TIBC-sat) were evaluated as screening procedures for idiopathic haemochromatosis in a non-diseased population. Special attention was paid to the influence of the analytical quality, but the effects of prevalence and discrimination limits were also considered. Changes in the analytical quality for S-ferritin and TIBC-sat used as single tests highly influenced the number of false test-positives. Increasing the coefficient of variation from 0.0 to 0.2 resulted in nearly a doubling of the number of false test-positives to be further investigated. Using even a high, yet achievable analytic quality with a low coefficient of variation of 0.056 and 0.059 for S-ferritin and TIBC-sat respectively, screening procedures had unacceptably high fractions of false test-positives and false test-negatives associated with any discrimination limit. If the prevalence of haemochromatosis is 0.003, the predictive value of a positive test result did not exceed 0.05, accepting a fraction of false test-negatives of 0.025. This was found to be too low for a screening test to be used in the general population. The combined use of S-ferritin and TIBC-sat resulted in higher performance with a sensitivity of 0.90, a specificity of 0.99 and a predictive value of a positive test result of 0.29 if a fraction of misclassification of 0.01 is accepted for each.

False Positive Reactions↗
PubMed1991

Screening for haemochromatosis: prevalence among Danish blood donors.

Hereditary haemochromatosis is an autosomal recessive disease that is genetically expressed by excessive accumulation of iron in the tissues, resulting in cirrhosis, diabetes mellitus, cardiomyopathy and hypogonadism. As the disease may be diagnosed before the appearance of symptoms, and prevented by repeated phlebotomies, there are strong implications for adoption of a screening procedure. Determinations of transferrin saturation (TS) and serum ferritin concentration (SF) were used to screen 4302 blood donors, who were selected for follow-up studies if they fulfilled any of the following three criteria: (i) TS greater than or equal to 0.7; (ii) TS greater than or equal to 0.5 together with SF greater than or equal to 150 micrograms l-1; (iii) SF greater than or equal to 300 micrograms l-1. A total of 58 subjects who fulfilled at least one of these criteria were reinvestigated, after which 18 individuals still fulfilled at least one criterion. Fifteen subjects having SF greater than or equal to 300 micrograms l-1 were offered liver biopsy and thirteen of these accepted. In one individual, no stainable iron was detected, and two subjects did not fulfil the previously established diagnostic criteria for the diagnosis of hereditary haemochromatosis. Ten subjects who had a high TS and liver iron grade 2-4 according to Bassett were classified accordingly as homozygotes. On the basis of these results, the prevalence of haemochromatosis in Denmark was estimated to be 0.0037-0.0046.

Adult↗
PubMed1990

Influence of analytical quality and preanalytical variations on measurements of cholesterol in screening programmes.

In screening programmes one should distinguish between the traditional bimodal distributions of results and a unimodal distribution as the basis for interpretation. A model for evaluation of the effects of biological within-subject and preanalytical variation as well as analytical variation is described. It is concluded that bias from blood sampling and analytical performance influences the outcome of screening programs significantly. At least three blood specimens are needed for estimating the homeostatic set point of cholesterol in individuals.

Chemistry, Clinical↗
PubMed1990

Analytical goal setting prior to selection of a method for glycated haemoglobin.

Without a consensus on either a reference method or a single glycated haemoglobin standard, the individual laboratory has to establish and secure its own assay method. Prior to selection of a method for glycated haemoglobin we used an assessment model and defined our clinical goals. Based on clinical goals it was possible to set up goals of analytical quality and evaluate available literature concerning the performance characteristics of different assay methods. We wanted a method that measured HbAlc, without measuring the labile intermediate pre-HbAlc, and that provided separate detection of haemoglobin variants. Low imprecision was required to secure the measured, non-diabetic reference interval, and to minimize random analytical error. We found the isoelectric focusing method the only one able to meet our goals, and a method evaluation was carried out. Clinical goals of analytical quality should always be defined before method selection and implementation. Using this model, we were able to establish a precise isoelectric focusing method that fulfilled our clinical goals by measuring HbAlc with a total coefficient of variation of 2.1% and a non-diabetic reference interval from 5.2% to 6.8% HbAlc.

Blood Chemical Analysis↗