Using the same vitamin-D-replete population to establish the reference range for 10 commercial PTH kits significantly improved the classification of haemodialysis patients according to the KDIGO target range.

The aim of this study was to establish creatinine growth curves separately for males and females that can be used to adjust childhood levels of serum creatinine to corresponding adult levels. Linear regression with fractional polynomials of age as independent variable was used to construct creatinine growth curves for a reference cohort (n ¼ 83,157 samples from Belgium and Sweden, age 2-40 years). Adjusted creatinine obtained from the growth curves was used to improve accuracy of estimated glomerular filtration rate (eGFR) based on the Lund-Malm€ o revised (LMR) equation in children. The LMR equation based on creatinine values adjusted to age 18 years was validated against measured GFR (mGFR) in a separate cohort of 4005 children from four different European countries. Validation metrics included median bias, precision, and accuracy expressed as percentage of estimates within ±30% (P 30) of mGFR. Remarkable improvements in bias and accuracy were observed; P 30 increased from 56% to 74% after creatinine adjustments in children with mGFR <75 mL/min/1.73 m 2 (n ¼ 932), while P 30 was relatively unchanged (89-90%) at mGFR !75 mL/min/1.73 m 2 (n ¼ 3073). The suggested approach with adjusted creatinine makes LMR applicable in children irrespective of their renal function.

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BackgroundSimultaneous measurement of 25(OH)D and 24,25(OH)2D is a new tool for predicting vitamin D deficiency and allows evaluating CYP24A1 lack of function. Interpretation of 24,25(OH)2D should be performed according to 25(OH)D levels and a ratio, called the vitamin D metabolite ratio (VMR) has been proposed for such a purpose. Unfortunately, the VMR can be expressed in different ways and cannot be used if 24,25(OH)2D concentrations are undetectable. Here, we propose evaluating the enzyme activity taking into consideration the probability that a normal population presents undetectable 24,25(OH)2D concentrations according to 25(OH)D levels. We thus retrospectively measured 25(OH)D and 24,25(OH)2D in a population of 1200 young subjects to evaluate the 25(OH)D threshold above which the enzyme was induced.MethodsSerum samples from 1200 infants, children, adolescent and young adults were used to simultaneously quantify 25(OH)D and 24,25(OH)2D by LCMS/MS.ResultsMedian (interquartile range [IQR]) levels were 20.6 (14.4–27.2) ng/mL for 25(OH)D. 172 subjects (14.3%) presented 24,25(OH)2D values below the LOQ. When 25(OH)D values were <11 ng/mL, 63.1% of subjects presented undetectable 24,25(OH)2D concentrations. Percentage decreased with increasing 25(OH)D values to become 19.7% for 25(OH)D comprised between 12 and 15 ng/mL, 5.1% for 25(OH)D between 16 and 20 and 0.7% for 25(OH)D >21 ng/mL.ConclusionsWe suggest using a statistical approach to evaluate CYP24A1 function according to 25(OH)D concentrations. Our results also show that vitamin D deficiency, as defined biochemically, could be around 20 ng/mL in infants, children, adolescent and young adults and that vitamin D deficiency could be evaluated on a more individual basis.

Background: Cardiac biomarkers elevations have been described after running exercise. Objective of our study was to check cardiac biomarker dynamics in well trained athletes and untrained middle aged apparently healthy men and to highlight the impact on the lab results interpretation in emergency department.Methods: Cardiac biomarkers for ischemic condition, cardiac stretch and fibrotic processes were tested in different type of runners before, directly after and 3 hours after running. Markers for inflammation, muscle disease and renal function were also measured.Results: Cardiac biomarker levels between groups were not statistically different in the pre-exercise samples for natriuretic peptides [B-type natriuretic peptide (BNP), N-terminal Pro BNP (NT-ProBNP)] and galectin-3 (Gal-3), only Troponin I levels were higher. Directly after exercise, all cardiac biomarker levels were higher compared to the baseline, Gal-3 and BNP levels decreased 3 hours after completion of the run.Troponin values continued to increase with highest levels 3 hours after exercise. Troponin T, NT-Pro-BNP and Gal-3 also showed significant correlation to markers of inflammation, fibrosis and renal function.Conclusions: Exercises of different intensity can be associated with biochemical abnormalities and longterm consequences are unknown. In chest pain patients presenting to the emergency department possible impact of exercise on test results, especially Troponin, should be checked.