Folate reference interval estimation in the Dutch general population

Background: Folate functions as an enzyme co-factor within the one-carbon metabolic pathway, providing key metabolites required for DNA synthesis and methylation. Hence, insufficient intake of folate can negatively affect health. As correct interpretation of folate status is dependent on a well-established reference interval, we set out to perform a new estimation following the restandardization of the Roche folate assay against the international folate standard. Materials and methods: The folate reference interval was estimated using samples obtained from the Dutch population-based Lifelines cohort. The reference interval was estimated using two methods: a nonparametric estimation combined with bootstrap resampling and by fitting the data to a gamma distribution. The lower reference limit was verified in a patient cohort by combined measurement of folate and homocysteine. Results: Dependent on the method used for estimation and in- or exclusion of individuals younger than 21 years of age, the lower reference limit ranged from 6.8 to 7.3 nmol/L and the upper reference limit ranged from 26 to 38.5 nmol/L. Applying a lower reference limit of 7.3 nmol/L resulted in the following percentage of folate deficiencies over a period of 12 months: general practitioner 15.5% (IQR 4.0%), general hospital 12.8% (IQR 5.3%), academic hospital 9.6% (IQR 4.3%). Conclusions: We estimated the folate reference interval in the Dutch general population which is not affected by a folic acid fortification program and verified the obtained lower reference limit by homocysteine measurements. Based on our results, we propose a folate reference interval independent of age of 7.3-38.5 nmol/

Use of Salivary Iodine Concentrations to Estimate the Iodine Status of Adults in Clinical Practice

BACKGROUND: Measurement of the 24-h urinary iodine concentration or urinary iodine excretion (UIE) is the gold standard to determine iodine status; however, this method is inconvenient. The use of salivary iodine could be a possible alternative since salivary glands express the sodium-iodine symporter. OBJECTIVES: We aimed to establish the correlation between the salivary iodine secretion and UIE, to evaluate the clinical applicability of the iodine saliva measurement. METHODS: We collected 24-h urine and saliva samples from 40 participants ≥18 y: 20 healthy volunteers with no specific diet (group 1), 10 patients with differentiated thyroid cancer with a low dietary intake (<50 μg/d, group 2), and 10 patients with a high iodine status as the result of the use of amiodarone (group 3). Urinary and salivary iodine were measured using a validated inductively coupled plasma MS method. To correct for differences in water content, the salivary iodine concentration (SIC) was corrected for salivary protein and urea concentrations (SI/SP and SI/SU, respectively). The intra- and inter-individual CVs were calculated, and the Kruskal-Wallis test and Spearman's correlation were used. RESULTS: The intra-individual CVs for SIC, SI/SP, and SI/SU were 63.8%, 37.7%, and 26.9%, respectively. The inter-individual CVs for SIC, SI/SP, and SI/SU were 77.5%, 41.6% and 47.0%, respectively. We found significant differences (P < 0.01) in urinary and salivary iodine concentrations between all groups [the 24-h UIE values were 176 μg/d (IQR, 96.1–213 μg/d), 26.0 μg/d (IQR, 22.0–37.0 μg/d), and 10.0*10(3) μg/d (IQR, 7.57*10(3)–11.4*10(3) μg/d) in groups 1–3, respectively; the SIC values were 136 μg/L (IQR, 86.3–308 μg/L), 71.5 μg/L (IQR, 29.5–94.5 μg/L), and 14.3*10(3) μg/L (IQR, 10.6*10(3)–25.6*10(3) μg/L) in groups 1–3, respectively]. Correlations between the 24-h UIE and SIC, SI/SP, and SI/SU values were strong (ρ = 0.80, ρ = 0.90, and ρ = 0.86, respectively; P < 0.01). CONCLUSIONS: Strong correlations were found between salivary and urinary iodine in adults with different daily iodine intakes. A salivary iodine measurement can be performed to assess the total iodine body pool, with the recommendation to correct for salivary protein or urea

Mythes en waarheden over kansen voor juridisch onderzoek bij NWO

In deze bijdrage worden aan de hand van door NWO verschafte gegevens honoreringspercentages van juridische en niet-juridische (sociaal-wetenschappelijke) onderzoeksaanvragen vergeleken, alsook de percentages tussen juridische sub-disciplines. De resultaten laten zien dat het aantal juridische onderzoeksaanvragen is toegenomen en dat de slagingskans van juridische voorstellen niet heel veel lager ligt (maar zeker niet hoger) dan die uit de andere disciplines gezamenlijk. Het onderzoek is niet meer dan een allereerste aanzet voor een feitelijke onderbouwing van en verdere discussie over de toekomst van juridisch onderzoek in Nederland

Mythes en waarheden over kansen voor juridisch onderzoek bij NWO

In deze bijdrage worden aan de hand van door NWO verschafte gegevens honoreringspercentages van juridische en niet-juridische (sociaal-wetenschappelijke) onderzoeksaanvragen vergeleken, alsook de percentages tussen juridische sub-disciplines. De resultaten laten zien dat het aantal juridische onderzoeksaanvragen is toegenomen en dat de slagingskans van juridische voorstellen niet heel veel lager ligt (maar zeker niet hoger) dan die uit de andere disciplines gezamenlijk. Het onderzoek is niet meer dan een allereerste aanzet voor een feitelijke onderbouwing van en verdere discussie over de toekomst van juridisch onderzoek in Nederland