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  • 1.
    Ekblom, Kim
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Oxidants and antioxidants in cardiovascular disease2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background

    Cardiovascular diseases, including myocardial infarction and stroke, are the main reason of death in Sweden and Western Europe. High iron stores are believed to produce oxygen radicals, which is the presumed putative mechanism behind lipid peroxidation, atherosclerosis and subsequent cardiovascular disease. Iron levels are associated with the hemochromatosis associated HFE single nucleotide polymorphisms C282Y and H63D.

    Bilirubin is an antioxidant present in relatively high levels in the human body. Several previous studies have found an association between high bilirubin levels and a lower risk for cardiovascular disease. Bilirubin levels are highly influenced by the common promoter polymorphism TA-insertion UGT1A1*28, the main reason for benign hyperbilirubinemia in Caucasians.

    There is a lack of prospective studies on both the association of iron and bilirubin levels, and the risk for myocardial infarction and ischemic stroke.

    Material and methods

    Iron, transferrin iron saturation, TIBC, ferritin and bilirubin were analyzed and HFE C282Y, HFE H63D and UGT1A1*28 were determined in myocardial infarction and stroke cases, and their double matched referents within the Northern Sweden Health and Disease Study Cohort.

    Results

    There were no associations between iron levels in the upper normal range and risk for myocardial infarction or stroke. No associations were seen for HFE-genotypes, except for a near fivefold increase in risk for myocardial infarction in HFE H63D homozygous women.

    Plasma bilirubin was lower in cases vs. referents both in the myocardial infarction and the stroke cohort. Despite a strong gene-dosage effect on bilirubin levels in both cases and referents, the UGT1A1*28 polymorphism did not influence the risk for myocardial infarction or stroke.

    Conclusion

    High iron stores are not associated with increased risk for neither myocardial infarction, nor stroke. There was no association between UGT1A1*28 and the risk for myocardial infarction or stroke. Consequently data suggests that other factors, which also may lower bilirubin, are responsible for the elevated risk observed in conjunction with lower bilirubin levels.

  • 2.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Stegmayr, Birgitta
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Johansson, Ingegerd
    Umeå University, Faculty of Medicine, Department of Odontology, Cariology.
    Van Guelpen, Bethany
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Public Health Sciences.
    Johansson, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Wiklund, Per-Gunnar
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Iron stores and HFE genotypes are not related to increased risk of ischemic stroke.: a prospective nested case-referent study2007In: Cerebrovascular Diseases, ISSN 1015-9770, E-ISSN 1421-9786, Vol. 24, no 5, p. 405-411Article in journal (Refereed)
    Abstract [en]

    Background: High iron levels can increase the formation of noxious oxygen radicals, which are thought to contribute to cerebrovascular disease. The aim of this prospective study was to determine if iron status and HFE genotypes constitute risk factors for stroke.

    Methods: First-ever stroke cases (231 ischemic and 42 hemorrhagic) and matched double referents from the population-based Northern Sweden cohorts were studied in a nested case-referent setting.

    Results: For total iron binding capacity, an increased risk of ischemic stroke was seen in the highest quartile (OR 1.80; 95% CI 1.14-2.83; p for trend 0.012). The highest quartile of transferrin iron saturation showed a decreased risk of ischemic stroke in men (OR 0.44; 95% CI 0.22-0.87; p for trend 0.028), but not in women. There was an increased risk of hemorrhagic stroke in the second (OR 4.07; 95% CI 1.09-15.20) and third quartile (OR 4.22; 95% CI 1.08-16.42) of ferritin. Neither quartiles of plasma iron concentrations nor the HFE C282Y and H63D genotypes were associated with ischemic or hemorrhagic stroke.

    Conclusions: Iron stores were not positively related to increased risk of ischemic stroke. Furthermore, HFE genotypes did not influence the risk of ischemic or hemorrhagic stroke. Copyright (c) 2007 S. Karger AG, Basel.

  • 3.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Jansson, Jan-Håkan
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Iron stores and HFE genotypes are not related to increased risk of first-time myocardial infarction: a prospective nested case-referent study2011In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 150, no 2, p. 169-172Article in journal (Refereed)
    Abstract [en]

    Objectives: Our objectives were to study the relationship between iron stores, HFE genotypes and the risk for first-ever myocardial infarction.

    Methods: First-ever myocardial infarction cases (n=618) and double matched referents from the Northern Sweden Health and Disease Cohort Study were studied in a prospective nested case-referent setting. Plasma iron, total iron binding capacity, transferrin iron saturation and ferritin were analyzed, as well as several confounders. HFE C282Y and H63D genotypes were determined.

    Results: There was an inverse risk association for myocardial infarction in the highest quartiles of iron (OR 0.68; 95% CI 0.48-0.96) and transferrin iron saturation (OR 0.62; 95% CI 0.42-0.89) in men. This association, however, was lost after adjusting for C-reactive protein. Women homozygous for H63D had a higher risk for myocardial infarction.

    Conclusions: No risk association between high iron stores and first-ever myocardial infarction was found. The higher risk in female H63D homozygotes is probably not related to iron metabolism.

  • 4.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Jansson, Jan-Håkan
    Medicinkliniken, Skellefteå lasarett.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Plasma Bilirubin and UGT1A1*28 Are Not Protective Factors Against First-Time Myocardial Infarction in a Prospective, Nested Case–Referent Setting2010In: Circulation: Cardiovascular Genetics, ISSN 1942-325X, E-ISSN 1942-3268, no 3, p. 340-347Article in journal (Refereed)
    Abstract [en]

    Background: Bilirubin, an effective antioxidant, shows a large variation in levels between individuals and has been positively associated with reduced cardiovascular disease risk. A major reason for the variability is a common promoter polymorphism, UGT1A1*28, which reduces the transcription of the enzyme that conjugates bilirubin, UDP-glucuronosyltransferase 1A1. The aim of the study was to evaluate a possible protective effect of plasma bilirubin and the UGT1A1*28 polymorphism against myocardial infarction in a prospective case-referent setting.

    Methods and Results: 618 subjects with a first-ever myocardial infarction (median event age 60.5 years, median lag time 3.5 years) and 1184 matched referents were studied. Plasma bilirubin was lower in cases vs. referents. Despite a strong gene-dosage effect on bilirubin levels in both cases and referents, the UGT1A1*28 polymorphism did not influence the risk of myocardial infarction. Among multiple other variables, serum iron showed one of the strongest associations with bilirubin levels.

    Conclusion: We found no evidence for a protective effect of the UGT1A1*28 polymorphism against myocardial infarction and consequently neither for bilirubin. The lower bilirubin levels in cases might be caused by decreased production, increased degradation or increased elimination.

  • 5.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Jansson, Jan-Håkan
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Response to letter regarding article "Plasma bilirubin and UGT1A1*28 are not protective factors against first-time myocardial infarction in a prospective nested case-referent setting"2011In: Circulation: Cardiovascular Genetics, ISSN 1942-325X, E-ISSN 1942-3268, Vol. 4, no 1, p. e2-Article in journal (Refereed)
  • 6.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Johansson, Lars
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Wiklund, Per-Gunnar
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Bilirubin and UGT1A1*28 are not associated with lower risk for ischemic stroke in a prospective nested case-referent setting.2010In: Cerebrovascular Diseases, ISSN 1015-9770, E-ISSN 1421-9786, Vol. 30, no 6, p. 590-596Article in journal (Refereed)
    Abstract [en]

    Background: Bilirubin, an antioxidant, has been associated with reduced cardiovascular disease risk. A major cause of elevated plasma bilirubin is the common UGT1A1*28 promoter polymorphism in the gene of the bilirubin-conjugating enzyme UDP-glucuronosyltransferase 1A1, which reduces transcription by 70%. Earlier studies reporting a protective effect of bilirubin on stroke have not included analysis of UGT1A1*28. The purpose of this study is to investigate if bilirubin and UGT1A1*28 are protective against ischemic stroke in a prospective case-referent setting. Methods: Cases with first-ever ischemic stroke (n = 231; median lag time 4.9 years) and 462 matched referents from the Northern Sweden Health and Disease Study Cohort were included. Plasma bilirubin was measured and UGT1A1*28 was analyzed by fragment analysis. Results: Plasma bilirubin was lower in cases than in referents, but the difference reached significance only for women. The UGT1A1*28 polymorphism (allele frequency 30%) showed a strong gene-dose relationship with bilirubin levels both among cases and referents, but was not associated with risk for stroke. Among multiple other variables analyzed, the strongest correlation with bilirubin was found for plasma iron. Conclusions: There was no evidence for a protective effect of the UGT1A1*28 polymorphism against stroke and consequently neither for bilirubin. The findings suggest that other factors influencing the risk for stroke might also affect bilirubin levels.

  • 7.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Johansson, Lars
    Medicinkliniken, Skellefteå lasarett.
    Osterman, Pia
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Wiklund, Per-Gunnar
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Bilirubin and UGT1A1*28, are not associated with lower risk for ischemic stroke in a prospective nested case-referent settingArticle in journal (Refereed)
    Abstract [en]

    Background: Bilirubin, an antioxidant, has been associated with reduced cardiovascular disease risk. A major cause of elevated plasma bilirubin is the common UGT1A1*28 promoter polymorphism in the gene of the bilirubin-conjugating enzyme UDP-glucuronosyltransferase-1A1, which reduces transcription by 70%. Earlier studies reporting a protective effect of bilirubin on stroke, have not included analysis of UGT1A1*28. The purpose of this study is to investigate if bilirubin and UGT1A1*28 are protective against ischemic stroke in a prospective case-referent setting.

    Methods: Cases with first-ever ischemic stroke (n=231; median lag time 4.9 years), and 462 matched referents from the The Northern Sweden Health and Disease Study Cohort were included. Plasma bilirubin was measured and UGT1A1*28 was analyzed by fragment analysis.

    Results: Plasma bilirubin was lower in cases than in referents, but the difference reached significance only for women. The UGT1A1*28 polymorphism (allele frequency 30%), showed a strong gene-dose relationship with bilirubin levels both among cases and referents, but was not associated with risk for stroke. Among multiple other variables analysed the strongest correlation with bilirubin was found for plasma iron.

    Conclusions: There was no evidence for a protective effect of the UGT1A1*28 polymorphism against stroke and consequently neither for bilirubin. The findings suggest that other factors influencing the risk for stroke also might affect bilirubin levels.

  • 8.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Marklund, Stefan L.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Palmqvist, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Van Guelpen, Bethany
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hallmans, Göran
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Weinehall, Lars
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hultdin, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Iron Biomarkers in Plasma, HFE Genotypes, and the Risk for Colorectal Cancer in a Prospective Setting2012In: Diseases of the Colon & Rectum, ISSN 0012-3706, E-ISSN 1530-0358, Vol. 55, no 3, p. 337-344Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: High iron levels can increase the formation of noxious oxygen radicals, which are thought to promote carcinogenesis. OBJECTIVE: The aim of this prospective study was to determine whether iron biomarkers and HFE genotypes, which influence iron regulation, constitute risk factors for colorectal cancer. DESIGN: This is a prospective nested case-referent study. SETTINGS: The study was performed within the population-based Northern Sweden Health and Disease Study. PATIENTS: The study included 226 cases of colorectal cancer and 437 matched referents. MAIN OUTCOME MEASURES: Conditional regression analysis was performed. Adjustments for smoking, smoking and BMI, and HFE C282Y and H63D were performed. RESULTS: The highest quintile of total iron-binding capacity showed significantly higher risk for colorectal cancer, unadjusted OR 2.35 (95% CI 1.38-4.02). When stratified by sex, the findings were only present in women (OR 3.34 (95% CI 1.59-7.02)). Ferritin was associated with reduced risk throughout quintiles 2 to 5 both in univariate and multivariate models. LIMITATIONS: Colorectal cancer may influence iron markers because of occult bleeding. Homozygotes for HFE C282Y were too few to make conclusions for this group. The relatively short follow-up time might be insufficient to detect risk of iron biomarkers. CONCLUSIONS: High iron levels do not increase the risk of colorectal cancer. HFE genotypes influencing iron uptake had no effect on colorectal cancer risk.

  • 9.
    Ekblom, Kim
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry. Department of Clinical Chemistry and Transfusion Medicine, Växjö Central Hospital, Växjö, Sweden.
    Petersson, Annika
    Introduction of Cost Display Reduces Laboratory Test Utilization2018In: American Journal of Managed Care, ISSN 1088-0224, E-ISSN 1936-2692, Vol. 24, no 5, p. E164-E169Article in journal (Refereed)
    Abstract [en]

    Objectives: To study the effects on the number of laboratory tests ordered after introduction of cost display (showing the cost in the computerized test ordering system at test ordering and test result delivery) and cost charge (requiring all primary healthcare centers to pay full laboratory costs of the ordered tests).

    Study design: The study included cost display for secondary healthcare centers (inpatient hospitals, emergency departments, and outpatient specialist providers) as well as publicly and privately operated primary healthcare centers (sites of nonemergency, nonspecialist healthcare). After 3 months cost charge was introduced by management for all primary healthcare centers.

    Methods: Information on laboratory test name in the test ordering system, resulting in cost display both at the moment of test ordering and at the presentation of the test result. Numbers of laboratory tests were obtained from the laboratory information system and calculated as tests per physician visit. Cost charge was managed through the established laboratory invoicing system.

    Results: In the publicly operated primary healthcare centers, neither if the interventions had any effect on laboratory test volume, nor did cost display have an effect in the privately operated primary healthcare centers. However, introduction of cost charge significantly decreased laboratory test ordering in the privately operated primary healthcare centers.In contrast, secondary healthcare centers lowered test volumes when cost display was introduced.

    Conclusions: The results support cost awareness and cost charge as means of reducing laboratory utilization. However, the outcome varies with the setting.

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