Data from: Simultaneous determination of underivatized vitamin B1 and B6 in whole blood by Reversed Phase Ultra High Performance Liquid Chromatography Tandem Mass spectrometry

Background: Vitamin B1 (thiamine-diphosphate) and B6 (pyridoxal-5’phosphate) are micronutrients. Analysis of these micronutrients is important to diagnose potential deficiency which often occurs in elderly people due to malnutrition, in severe alcoholism and in gastrointestinal compromise due to bypass surgery or disease. Existing High Performance Liquid Chromatography (HPLC) based methods include the need for derivatization and long analysis time. We developed an Ultra High Performance Liquid Chromatography Tandem Mass spectrometry (UHPLC-MS/MS) assay with internal standards for simultaneous measurement of underivatized thiamine-diphosphate and pyridoxal-5’phosphate without use of ion pairing reagent. Methods: Whole blood, deproteinized with perchloric acid, containing deuterium labelled internal standards thiamine-diphosphate(thiazole-methyl-D3) and pyridoxal-5’phosphate(methyl-D3), was analyzed by UHPLC-MS/MS. The method was validated for imprecision, linearity, recovery and limit of quantification. Alternate (quantitative) method comparisons of the new versus currently used routine HPLC methods were established with Deming regression. Results: Thiamine-diphosphate and pyridoxal-5’phosphate were measured within 2.5 minutes instrumental run time. Limits of detection were 2.8 nmol/L and 7.8 nmol/L for thiamine-diphosphate and pyridoxal-5’phosphate respectively. Limit of quantification was 9.4 nmol/L for thiamine-diphosphate and 25.9 nmol/L for pyridoxal-5’phosphate. The total imprecision ranged from 3.5-7.7 % for thiamine-diphosphate (44-157 nmol/L) and 6.0-10.4 % for pyridoxal-5’phosphate (30-130 nmol/L). Extraction recoveries were 101-102% ± 2.5 % (thiamine-diphosphate) and 98-100 % ± 5 % (pyridoxal-5’phosphate). Deming regression yielded slopes of 0.926 and 0.990 in patient samples (n=282) and national proficiency testing samples (n=12) respectively, intercepts of +3.5 and +3 for thiamine-diphosphate (n=282 and n=12) and slopes of 1.04 and 0.84, intercepts of -2.9 and +20 for pyridoxal-5’phosphate (n=376 and n=12). Conclusion: The described UHPLC-MS/MS method allows simultaneous determination of underivatized thiamine-diphosphate and pyridoxal-5’phosphate in whole blood without intensive sample preparation

Lactate point-of-care testing for acidosis: Cross-comparison of two devices with routine laboratory results

Objectives: Lactate is a major parameter in medical decision making. During labor, it is an indicator for fetal acidosis and immediate intervention. In the Emergency Department (ED), rapid analysis of lactate/blood gas is crucial for optimal patient care. Our objectives were to cross-compare-for the first time-two point-of-care testing (POCT) lactate devices with routine laboratory results using novel tight precision targets and evaluate different lactate cut-off concentrations to predict metabolic acidosis. Design and methods: Blood samples from the delivery room (n=66) and from the ED (n=85) were analyzed on two POCT devices, the StatStrip-Lactate (Nova Biomedical) and the iSTAT-1 (CG4+ cassettes, Abbott), and compared to the routine laboratory analyzer (ABL-735, Radiometer). Lactate concentrations were cross-compared between these analyzers. Results: The StatStrip correlated well with the ABL-735 (R=0.9737) and with the iSTAT-1 (R=0.9774) for lactate in umbilical cord blood. Lactate concentrations in ED samples measured on the iSTAT-1 and ABL-735 showed a correlation coefficient of R=0.9953. Analytical imprecision was excellent for lactate and pH, while for pO2 and pCO2 the coefficient of variation was relatively high using the iSTAT-1. Conclusion: Both POCT devices showed adequate analytical performance to measure lactate. The StatStrip can indicate metabolic acidosis in 1 μl blood and will be implemented at the delivery room. Keywords: Lactate, Point-of-care testing, Blood gas, Fetal acidosi

Rapid and Reliable Measurement of Highly Elevated Blood Ammonia Concentrations in Children

Peer Reviewe

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Emotional, Neurohormonal, and Hemodynamic Responses to Mental Stress in Tako-Tsubo Cardiomyopathy

Tako-Tsubo cardiomyopathy (TTC) is characterized by apical ballooning of the left ventricle and symptoms and signs mimicking acute myocardial infarction. The high catecholamine levels in the acute phase of TTC and common emotional triggers suggest a dysregulated stress response system. This study examined whether patients with TTC show exaggerated emotional, neurohormonal, and hemodynamic responses to mental stress. Patients with TTC (n = 18; mean age 68.3 ± 11.7, 78% women) and 2 comparison groups (healthy controls, n = 19; mean age 60.0 ± 7.6, 68% women; chronic heart failure, n = 19; mean age 68.8 ± 10.1, 68% women) performed a structured mental stress task (anger recall and mental arithmetic) and low-grade exercise with repeated assessments of negative emotions, neurohormones (catecholamines: norepinephrine, epinephrine, dopamine, hypothalamic-pituitary-adrenal axis hormones: adrenocorticotropic hormone [ACTH], cortisol), echocardiography, blood pressure, and heart rate. TTC was associated with higher norepinephrine (520.7 ± 125.5 vs 407.9 ± 155.3 pg/ml, p = 0.021) and dopamine (16.2 ± 10.3 vs 10.3 ± 3.9 pg/ml, p = 0.027) levels during mental stress and relatively low emotional arousal (p <0.05) compared with healthy controls. During exercise, norepinephrine (511.3 ± 167.1 vs 394.4 ± 124.3 pg/ml, p = 0.037) and dopamine (17.3 ± 10.0 vs 10.8 ± 4.1 pg/ml, p = 0.017) levels were also significantly higher in patients with TTC compared with healthy controls. In conclusion, catecholamine levels during mental stress and exercise were elevated in TTC compared with healthy controls. No evidence was found for a dysregulated hypothalamic-pituitary-adrenal axis or hemodynamic responses. Patients with TTC showed blunted emotional arousal to mental stress. This study suggests that catecholamine hyper-reactivity and not emotional hyper-reactivity to stress is likely to play a role in myocardial vulnerability in TTC. Tako-Tsubo cardiomyopathy (TTC) is characterized by apical ballooning of the left ventricle (LV) and symptoms and signs mimicking acute myocardial infarction.1, 2 and 3 Emotional triggers are common in TTC,4 and the high catecholamine levels on admission1 suggest a dysregulated stress response system. This study examined emotional, neurohormonal, and hemodynamic responses to acute mental stress, comparing patients with TTC to healthy controls and cardiac patients with heart failure (HF). We investigated whether emotional, neurohormonal (catecholamines and hypothalamic-pituitary-adrenal [HPA]-related measures adrenocorticotropic hormone [ACTH] and cortisol), and hemodynamic (LV function, blood pressure, and heart rate [HR]) responses to a structured mental stress task are exaggerated in patients with a history of TTC compared with healthy controls and patient controls with stable HF. We also examined potential response patterns to low-grade exercise challenge for comparison purposes

Newborn blood spot screening for cystic fibrosis with a four-step screening strategy in the Netherlands.

Newborn screening for cystic fibrosis (NBSCF) was introduced in the Dutch NBS program in 2011 with a novel strategy

Newborn blood spot screening for cystic fibrosis with a four-step screening strategy in the Netherlands.

Newborn screening for cystic fibrosis (NBSCF) was introduced in the Dutch NBS program in 2011 with a novel strategy

Second-tier testing for 21-hydroxylase deficiency in the Netherlands; a newborn screening pilot study.

BACKGROUND: Newborn screening (NBS) for classic congenital adrenal hyperplasia (CAH) consists of 17-hydroxyprogesterone (17-OHP) measurement with gestational age-adjusted cut-off values. A second heel puncture (HP) is performed in newborns with inconclusive results to reduce false-positives. We assessed the accuracy and turnaround time of the current CAH NBS-algorithm and compared this to alternative algorithms by performing a second-tier 21-deoxycortisol (21-DF) pilot-study. METHODS: Dried blood spots (DBS) of newborns with inconclusive and positive 17-OHP (immunoassay) first HP results were sent from regional NBS laboratories to the Amsterdam UMC Endocrine Laboratory. In 2017-2019 21-DF concentrations were analyzed by liquid chromatography-tandem mass spectrometry, in parallel with routine NBS. Diagnoses were confirmed by mutation analysis. RESULTS: 328 DBS were analyzed. 37 newborns had confirmed classic CAH, 33 were false-positive and 258 were categorized as negative in the second HP following the current algorithm. In the second-tier, all 37 confirmed CAH had elevated 21-DF concentrations, all 33 false-positives and 253/258 second HP negatives had undetectable 21-DF concentrations. The elevated 21-DF of the other five newborns may be NBS false-negatives or second-tier false-positives. Adding the second-tier to inconclusive first HPs reduced the number of false-positives to 11 and prevented all 286 second HPs. Adding the second-tier to both positive and inconclusive first HPs eliminated all false-positives at the cost of delayed referral for 31 CAH patients (1-4 days). CONCLUSION: Application of the second-tier 21-DF measurement to inconclusive first HPs improved our CAH NBS by reducing false-positives, abolishing the second HP and thereby shortening referral time