Om Dekkers

Publications (3)12.58 Total impact

• Article: Increased levels of free thyroxine and risk of venous thrombosis in a large population-based prospective study.

  J Debeij, O M Dekkers, B O Asvold, S C Christiansen, I A Naess, J Hammerstrom, F R Rosendaal, S C Cannegieter
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  ABSTRACT:   Recent studies have shown that high levels of free thyroxine (FT4), even without leading to hyperthyroidism, are associated with a procoagulant state. The aim of our study was to determine whether high levels of thyroid hormones are associated with an increased risk of venous thrombosis. From a prospective nested case-cohort design within the second Nord-Trøndelag Health Study (HUNT2) cohort (1995-1997; 66,140 subjects), all patients with venous thrombosis during follow-up (n=515) and 1476 randomly selected age-stratified and sex-stratified controls were included. Relative and absolute risks for venous thrombosis were calculated for different cut-off levels of thyroid hormones on the basis of percentiles in the controls and different times between blood sampling and thombosis. In subjects with an FT4 level above the 98th percentile (17.3 pmol L(-1)), the odds ratio (OR) was 2.5 (95% confidence interval [CI] 1.3-5.0) as compared with subjects with levels below this percentile. For venous thrombosis within 1 year from blood sampling, this relative risk was more pronounced, with an OR of 4.8 (95% CI 1.7-14.0). Within 0.5 years, the association was even stronger, with an OR of 9.9 (95% CI 2.9-34.0, adjusted for age, sex, and body mass index). For thyroid-stimulating hormone, the relationship was inverse and less pronounced. The absolute risk within 6 months in the population for FT4 levels above the 98th percentile was 6.1 per 1000 person-years (95% CI 1.7-15.7). Levels of FT4 at the upper end of the normal range are a strong risk factor for venous thrombosis. The risk increased with higher levels of thyroxine and shorter time between blood sampling and thrombosis. Further studies on the effect of clinical hyperthyroidism are warranted.
  Journal of Thrombosis and Haemostasis 06/2012; 10(8):1539-46. · 5.73 Impact Factor
• Article: Comparison of the cortisol responses to testing with two doses of ACTH in patients with suspected adrenal insufficiency.

  O M Dekkers, J M Timmermans, J W A Smit, J A Romijn, A M Pereira
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  ABSTRACT: To compare the cortisol response of the 1 μg and the 250 μg ACTH test in a large study of patients with suspected adrenal insufficiency. Retrospective cohort study. Single center study assessing patients tested for primary or secondary adrenal insufficiency between January 2004 and December 2007, who had both ACTH tests (1 μg and 250 μg; n=207) within a time interval of 6 weeks. Test results were compared with a Bland-Altman plot and McNemar's test. The mean difference between the cortisol responses in the two ACTH tests was 26 nmol/l (95% confidence interval (CI) 13, 40), showing a marginally higher response for the 250 μg test. The diagnostic performances of the two tests were similar (P=0.49) using a cut-off value for cortisol of 550 nmol/l. A normal cortisol response to the 1 μg ACTH test could be accompanied by an abnormal response to the 250 μg ACTH test, and vice versa. This study shows that the 1 μg and the 250 μg ACTH tests have comparable cortisol responses in patients with suspected adrenal insufficiency. However, in individual patients, the difference in cortisol response to the two tests can be substantial, and the response in the 250 μg test is not invariably higher than the response in a 1 μg test.
  European Journal of Endocrinology 10/2010; 164(1):83-7. · 3.42 Impact Factor
• Article: Clinical outcomes after estimated versus calculated activity of radioiodine for the treatment of hyperthyroidism: systematic review and meta-analysis.

  A de Rooij, J P Vandenbroucke, J W A Smit, M P M Stokkel, O M Dekkers
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  ABSTRACT: Despite the long experience with radioiodine for hyperthyroidism, controversy remains regarding the optimal method to determine the activity that is required to achieve long-term euthyroidism. To compare the effect of estimated versus calculated activity of radioiodine in hyperthyroidism. Design Systematic review and meta-analysis. We searched the databases Medline, EMBASE, Web of Science, and Cochrane Library for randomized and nonrandomized studies, comparing the effect of activity estimation methods with dosimetry for hyperthyroidism. The main outcome measure was the frequency of treatment success, defined as persistent euthyroidism after radioiodine treatment at the end of follow-up in the dose estimated and calculated dosimetry group. Furthermore, we assessed the cure rates of hyperthyroidism. Three randomized and five nonrandomized studies, comparing the effect of estimated versus calculated activity of radioiodine on clinical outcomes for the treatment of hyperthyroidism, were included. The weighted mean relative frequency of successful treatment outcome (euthyroidism) was 1.03 (95% confidence interval (CI) 0.91-1.16) for estimated versus calculated activity; the weighted mean relative frequency of cure of hyperthyroidism (eu- or hypothyroidism) was 1.03 (95% CI 0.96-1.10). Subgroup analysis showed a relative frequency of euthyroidism of 1.03 (95% CI 0.84-1.26) for Graves' disease and of 1.05 (95% CI 0.91-1.19) for toxic multinodular goiter. The two main methods used to determine the activity in the treatment of hyperthyroidism with radioiodine, estimated and calculated, resulted in an equally successful treatment outcome. However, the heterogeneity of the included studies is a strong limitation that prevents a definitive conclusion from this meta-analysis.
  European Journal of Endocrinology 09/2009; 161(5):771-7. · 3.42 Impact Factor