Publications by authors named "Jos P Wielders"

Pituitary adenoma is the main cause of hyperprolactinaemia; however, physicians should be aware that the pituitary is not always to blame. There are many other physiological and pathological causes for hyperprolactinaemia, and the contribution of stress, medication and the presence of macroprolactin should not be overlooked. We describe three patients - a 19-year-old female, a 28-year-old female and a 20-year-old male - in whom hyperprolactinaemia was due to medication use, physical stimulation of the nipple and a combination of macroprolactianaemia with a microadenoma, respectively.

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Importance: Anemia affects most pregnant African women and is predominantly due to iron deficiency, but antenatal iron supplementation has uncertain health benefits and can increase the malaria burden.

Objective: To measure the effect of antenatal iron supplementation on maternal Plasmodium infection risk, maternal iron status, and neonatal outcomes.

Design, Setting, And Participants: Randomized placebo-controlled trial conducted October 2011 through April 2013 in a malaria endemic area among 470 rural Kenyan women aged 15 to 45 years with singleton pregnancies, gestational age of 13 to 23 weeks, and hemoglobin concentration of 9 g/dL or greater.

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Background: The Roche Elecsys Vitamin D Total competitive protein-binding assay uses recombinant vitamin D binding protein for measuring 25-hydroxyvitamin D (25-OHD), which is different from commonly used antibody assays.

Methods: The assay, standardized against LC-MS/MS, was tested at four sites. Evaluation included precision; between-laboratory variability; functional sensitivity; correlation to LC-MS/MS, HPLC, and immunoassays; as well as robustness, traceability, and EQAS performance.

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Bone-targeting therapeutic radiopharmaceuticals are effective agents for treatment of painful bone metastases. Rhenium-188-HEDP is such a therapeutic radiopharmaceutical and has advantages over commercially available alternatives in terms of efficacy, safety and the ability to be produced on-site, allowing rapid treatment upon presentation of patients with pain. Unlike many other radiopharmaceuticals, there are no standardized preparation methods for Rhenium-188-HEDP.

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Background: Presence of the 3-epi-25-hydroxyvitamin D3 [3-epi-25(OH)D3] metabolite affects accurate determination of 25(OH)D3 by most routine liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods and to an unknown extent in present immuno- and protein binding assays. We studied 3-epi-25(OH)D3 cross-reactivity in a competitive protein binding (CPB) assay (Roche Elecsys).

Methods: Neonatal samples, containing up to 58% of 3-epi-25(OH)D3 were used for measurement by the CPB assay and by an LC-MS/MS method separating 25(OH)D3 and 3-epi-25(OH)D3.

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Carbohydrate-deficient transferrin (CDT) is a generic term that refers to the transferrin glycoforms whose concentration in blood is temporarily increased by sustained alcohol consumption. Due to high clinical specificity, CDT was proposed as a biomarker of heavy alcohol use and has been available for about 20 years. A number of methods have been developed for CDT measurement based on different analytical techniques and principles and without any harmonization or calibration to a reference method.

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Background: Excessive intake of alcohol is often associated with low or subnormal levels of vitamin D even in the absence of active liver disease. As vitamin D deficiency is a well-recognized cause of myopathy, alcoholic myopathy might be related to vitamin D deficiency. Chronic alcoholic myopathy affects approximately half of chronic alcoholics and is characterized by the insidious development of muscular weakness and wasting.

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Background: Neutrophil-gelatinase associated lipocalin (NGAL), a tubular injury marker, is associated with iron metabolism in hemodialysis patients. We investigated whether serum NGAL levels reflect iron metabolism in combined chronic heart failure and chronic kidney disease (CHF/CKD) and whether treatment with low-dose erythropoietin stimulating agent (ESA) modulates NGAL levels.

Methods: In the EPOCARES trial (ClinTrialsNCT00356733) serum NGAL, hepcidin-25, transferrin saturation (TSAT), reticulocyte hemoglobin content (Ret-He) and endogenous erythropoietin (EPO) levels were measured.

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Background: Measurement of serum 25-hydroxyvitamin D [25(OH)D] is used to assess vitamin D status. We evaluated the analytical performance of a new automated assay, Elecsys Vitamin D Total (Roche Diagnostics, Mannheim, Germany), based on competitive protein binding.

Methods: The Elecsys assay was tested for imprecision, linearity and functional sensitivity at three test-sites and compared to a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, a high-performance liquid chromatography (HPLC) method and the Liaison 25(OH) Vitamin D Total immunoassay (Diasorin).

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Objectives: Measurement of serum 25-hydroxyvitamin D [25(OH)D] is generally considered to be a reliable indicator of vitamin D status. The recent increase in diversity of 25(OH)D assays prompted us to evaluate the performance of chromatographic methods (two in-house ID-LC-MS/MS and HPLC (ClinRep, Recipe)), a protein binding method (Cobas-25(OH)D-total, Roche) and immunochemical methods (Liaison and RIA (Diasorin), iSYS (IDS), ADVIA Centaur (Siemens), and Architect i1000 and i2000 (Abbott)).

Methods: Blood was drawn from randomly selected outpatients (N=60) at one site after informed consent.

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Abstract Background: Measurement of serum 25-hydroxyvitamin D [25(OH)D] is used to assess vitamin D status. We evaluated the analytical performance of a new automated assay, Elecsys Vitamin D Total (Roche Diagnostics, Mannheim, Germany), based on competitive protein binding. Methods: The Elecsys assay was tested for imprecision, linearity and functional sensitivity at three test-sites and compared to a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, a high-performance liquid chromatography (HPLC) method and the Liaison 25(OH) Vitamin D Total immunoassay (Diasorin).

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Background: Asymptomatic carriage of Giardia intestinalis is highly prevalent among children in developing countries, and evidence regarding its role as a diarrhea-causing agent in these settings is controversial. Impaired linear growth and cognition have been associated with giardiasis, presumably mediated by malabsorption of nutrients. In a prospective cohort study, we aim to compare diarrhea rates in pre-school children with and without Giardia infection.

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Background: Carbohydrate-deficient transferrin (CDT) is used as a marker for chronic alcohol abuse. The presence of genetic transferrin variants might affect an individual's iron status and can interfere with CDT analysis. We report on the identification of a patient carrying a novel transferrin variant.

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Aims: Heart failure (HF) is common in geriatric patients. Clinicians face diagnostic challenges primarily due to comorbidity and limited access to echocardiography. The purpose of this study was to identify independent determinants of the presence of HF in geriatric outpatients and to determine the optimal diagnostic strategy.

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Vitamin-D deficiency is no longer to be seen only as a cause of osteomalacia, rickets and osteoporosis. There is a causal relationship with muscle function and also with the functioning of our immune system. Furthermore, vitamin-D deficiency is associated with a higher risk of autoimmune diseases and several forms of malignancy, such as prostate, colon and breast cancer.

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Carbohydrate-deficient transferrin (CDT) is a descriptive term used for a temporary change in the transferrin glycosylation profile caused by alcohol, and used as a biomarker of chronic high alcohol consumption. The use of an array of methods for measurement of CDT in various absolute or relative amounts, and sometimes covering different transferrin glycoforms, has complicated the comparability of results and caused confusion among medical staff. This situation prompted initiation of an IFCC Working Group on CDT standardization.

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Background: Carbohydrate-deficient transferrin (CDT) measurement on the multicapillary system Capillarys™ is characterized by high throughput and an on-line sample pre-treatment. This study evaluates the linearity and the precision of this technique, the correlation with the candidate reference method and the effect of genetic transferrin variants. Upper reference limit and cut-off values were calculated.

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Background: The nocturnal endogenous melatonin rise, which is associated with the onset of sleep propensity, is absent in haemodialysis patients. Information on melatonin rhythms in chronic kidney disease (CKD) is limited. Clear relationships exist between melatonin, core body temperature and cortisol in healthy subjects.

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Background: Urine microscopic analysis is hampered by its lack in standardisation and semi-quantitative reports, resulting in limited reliability. Automation of urinalysis could overcome these problems.

Methods: We compared the performance of the iQ200 with traditional microscopy and strip analysis in routine urinalysis.

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Background: An incomplete separation of disialotransferrin (CDT) and trisialotransferrin (a non-CDT isoform) may cause false-positive CDT results in alcohol abuse testing. We describe a currently unknown disialotransferrin-trisialotransferrin-bridging phenomenon (di-tri-bridge) appearing with high prevalence in serum from liver cirrhosis patients.

Methods: Twenty one consecutive serum samples with a di-tri-bridge encountered in routine CDT HPLC (Clin-Rep(R)-CDT-on-line, Recipe) were investigated by a candidate reference CDT HPLC method, by capillary electrophoresis (Capillarys-CDT, Sebia) and by transferrin genotyping.

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Background: alpha(1)-Antitrypsin (alpha(1)AT) deficiency predisposes individuals to chronic obstructive pulmonary disease (COPD) and/or liver disease. Phenotyping of the protein by isoelectric focusing is often used to characterize alpha(1)AT deficiency, but this method may lead to misdiagnosis (e.g.

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