Association of Serum Trimethylamine-N-Oxide Concentration from Childhood to Early Adulthood with Age and Sex.

BACKGROUND: Primary prevention is the cornerstone of cardiometabolic health. In the randomized, controlled Special Turku Coronary Risk Factor Intervention Project (STRIP), dietary counseling intervention was given to children from infancy to 20 years of age and a follow-up was completed at age 26 years. We investigated the associations of age, sex, gut microbiome, and dietary intervention with the gut metabolite and the cardiac biomarker trimethylamine-N-oxide (TMAO). METHODS: Overall, 592 healthy participants (females 46%) from STRIP were investigated. Compared to the control group, the intervention group had received dietary counseling between ages 7 months and 20 years focused on low intakes of saturated fat and cholesterol and the promotion of fruit, vegetable, and whole-grain consumption. TMAO serum concentrations were measured by a liquid chromatography-tandem mass spectrometry method at ages 11, 13, 15, 17, 19, and 26 years. Microbiome composition was assessed using 16S rRNA gene sequencing at 26 years of age. RESULTS: TMAO concentrations increased from age 11 to 26 years in both sexes. At all measurement time points, males showed significantly higher serum TMAO concentrations compared to females, but concentrations were similar between the intervention and control groups. A direct association between TMAO concentrations and reported fiber intake was found in females. Gut microbiome analysis did not reveal associations with TMAO. CONCLUSIONS: TMAO concentration increased from childhood to early adulthood but was not affected by the given dietary intervention. In females, TMAO concentrations could be directly associated with higher fiber intake suggesting sex-specific differences in TMAO metabolism.

Performance evaluation of a smartphone-based home test for fecal calprotection.

OBJECTIVES: Fecal calprotectin (FC) serves as a non-invasive marker for the assessment of gut inflammation in patients with inflammatory bowel disease (IBD). Laboratory measurements are usually performed with immunologic methods like enzyme-linked immunosorbent assay. Recently, quantitative home tests based on the lateral flow technology with smartphones as read-out devices have been developed. We compared the quantitative and qualitative performance of the quantitative lateral flow home test Preventis SmarTest® Calprotectin Home and the immunological test used in our laboratory (Eurospital Calprest® Turbo). METHODS: Fourty-five routine samples were analyzed in parallel with both tests according to the manufacturer's instructions. The read-out of the home test was performed with two smartphones (Apple iPhone 14 Pro and Samsung Galaxy XCover 5). The qualitative interpretation (positive, negative, borderline) was conducted using the cut-offs provided by the manufacturers. RESULTS: Statistically significant correlations with the laboratory standard method were observed for both smartphones (Spearman's rho 0.703 and 0.715, all p<0.005). The home test showed systematically higher concentrations compared to the routine assay. We found minimal qualitative agreement between the two tests (Cohen's kappas (κ)=0.323 and 0.300; p=0.003 and 0.005) showing a lower rate of positives with the home test. Both used smartphones showed good quantitative and qualitative agreement. CONCLUSIONS: The tests are quantitatively not interchangeable. However, the home test may be applicable for the serial follow-up management of patients with IBD. The higher rate of samples classified as negative with the home test may lead to an underestimation of affected patients.

The role of functional vitamin D deficiency and low vitamin D reservoirs in relation to cardiovascular health and mortality.

OBJECTIVES: The role of vitamin D deficiency in cardiovascular disease (CVD) is controversial. Inherent biological and analytical limitations compromise the specificity of widely used 25-hydroxyvitamin D [25(OH)D] cut-offs. Simultaneous determination of 25(OH)D and 24,25-dihydroxyvitamin D [24,25(OH)2D] permits a functional assessment of vitamin D metabolism. The present study compared the associations of functional vitamin D deficiency and low vitamin D reservoirs with CVD mortality and CVD burden. METHODS: 25(OH)D, 24,25(OH)2D, the degree of coronary obstruction on angiography, high-sensitive cardiac troponin T (hs-cTnT), N-terminal brain natriuretic peptide (NT-proBNP), and 10-year CVD mortality were obtained from 2,456 participants of the LURIC (Ludwigshafen Risk and Cardiovascular Health) study. RESULTS: Neither low 25(OH)D concentrations nor functional vitamin D deficiency were associated with the number of atherosclerotic coronary arteries or the degree of coronary obstruction. Over a median follow-up of 9.9 years, 454 participants died (23.6 %) due to CVD. CVD mortality was doubled in individuals with 25(OH)D concentrations below the widely used cut-off for deficiency of <50 nmol/L [20 ng/mL] (21.6 vs. 11.5 %). In individuals with and without functional vitamin D deficiency, CVD mortality was 25.0 and 16.7 %, respectively. NT-proBNP and heart failure prevalence were also higher in vitamin D deficient individuals. CONCLUSIONS: Vitamin D deficient individuals have markedly higher CVD mortality, but only marginally higher hs-cTnT concentrations. A higher prevalence of heart failure and higher NT-proBNP concentrations suggest a link between vitamin D deficiency and cardiac function. The traditional and metabolic assessment of vitamin D status showed comparable associations for the different parameters of cardiac health.

Vitamin D and vitamin K status in postmenopausal women with normal and low bone mineral density.

OBJECTIVES: Vitamin D and K are believed to promote bone health, but existing evidence is controversial. This study aimed to measure several metabolites of both vitamins by liquid chromatography tandem mass spectrometry (LC-MS/MS) in a cohort of postmenopausal women with low and normal bone mineral density (BMD). METHODS: Vitamin metabolites (25-hydroxyvitamin D (25[OH]D), 24,25-dihydroxyvitamin D (24,25(OH)2D), phylloquinone (K1), menaquinone-4 (MK-4) and MK-7) were measured in 131 serum samples by LC-MS/MS. The vitamin D metabolite ratio (VMR) was calculated. Parathyroid hormone (PTH), type I procollagen-N-terminal-peptide (PINP) and C-terminal telopeptides of type I collagen (CTX-I) were measured by immunoassay. Dual X-ray absorptiometry was performed to identify participants with normal (T-score>-1) and low (T-score<-1) BMD. RESULTS: Mean age was 58.2±8.5 years. BMD was normal in 68 and low in 63 women. Median (interquartile range) for 25(OH)D and total vitamin K concentrations were 53.5 (39.6-65.9) nmol/L and 1.33 (0.99-2.39) nmol/L. All vitamin metabolites were comparable in individuals with normal and low BMD. Furthermore, BMD and trabecular bone score were comparable in participants with adequate and inadequate vitamin status (at least one criterion was met: 25(OH)D <50 nmol/L, 24,25(OH)2D <3 nmol/L, VMR <4 %, total vitamin K <0.91 nmol/L). PTH, but not PINP or CTX-I, was inversely correlated with 25(OH)D, 24,25(OH)2D and VMR. Synergistic effects between vitamin D and K were not observed. CONCLUSIONS: Vitamin D and K status is not related to BMD and trabecular bone quality in postmenopausal women. Inverse associations were only seen between vitamin D metabolites and PTH.

Functional Assessment of Vitamin D Status by a Novel Metabolic Approach: The Low Vitamin D Profile Concept.

BACKGROUND: Determining serum 25-hydroxyvitamin D [25(OH)D], 24,25-dihydroxyvitamin D [24,25(OH)2D] and the vitamin D metabolite ratio (VMR) allows the identification of individuals with a low vitamin D metabolite profile. Here, we evaluated if such a functional approach provides superior diagnostic information to serum 25(OH)D alone. METHODS: 25(OH)D, 24,25(OH)2D, and the VMR were determined in participants of the DESIRE (Desirable Vitamin D Concentrations, n = 2010) and the LURIC (Ludwigshafen Risk and Cardiovascular Health, n = 2456) studies. A low vitamin D metabolite profile (vitamin D insufficiency) was defined by a 24,25(OH)2D concentration <1.2 ng/mL (<3 nmol/L) and a VMR <4%. Parathyroid hormone (PTH) and bone turnover markers were measured in both cohorts, whereas 10-year mortality data was recorded in LURIC only. RESULTS: The median age in DESIRE and LURIC was 43.3 and 63.8 years, respectively. Median 25(OH)D concentrations were 27.2 ng/mL (68.0 nmol/L) and 15.5 ng/mL (38.8 nmol/L), respectively. Serum 25(OH)D deficiency, defined as <20.2 ng/mL (<50 nmol/L), was present in 483 (24.0%) and 1701 (69.3%) participants of DESIRE and LURIC, respectively. In contrast, only 77 (3.8%) and 521 (21.2%) participants had a low vitamin D metabolite profile. Regardless of the serum 25(OH)D concentration, a low vitamin D metabolite profile was associated with a significantly higher PTH, accelerated bone metabolism, and higher all-cause mortality than an unremarkable vitamin D metabolite profile. CONCLUSIONS: The personalized assessment of vitamin D status using a functional approach better identifies patients with accelerated bone metabolism and increased mortality than the use of a fixed 25(OH)D cutoff of 20 ng/mL (50 nmol/L).

The Use of Next-Generation Sequencing in Pharmacogenomics.

BACKGROUND: Next-generation sequencing (NGS) methods have become more commonly performed in clinical and research laboratories. METHODS: This review summarizes the current laboratory NGS-based diagnostic approaches in pharmacogenomics including targeted multi-gene panel sequencing, whole-exome sequencing (WES), and whole-genome sequencing (WGS). RESULTS: Clinical laboratories perform multiple non-uniform types of pharmacogenetic panels, which can reduce the overall number of single-gene tests to be more cost-efficient. Compared to the targeted multi-gene panels, which are not typically designed to detect novel variants, WES and WGS have a greater potential to identify secondary pharmacogenomic findings, which might be predictive for the pharmacotherapy outcome of different patient settings. WGS overcomes the limitations of WES enabling a more accurate exome-sequencing at appropriate coverage and the sequencing of non-coding regions. Different NGS-based study designs with different test strategies and study populations, varying sample sizes, and distinct analytical and interpretation procedures lead to different identification results of pharmacogenomic variants. CONCLUSIONS: The rapid progress in gene sequencing technologies will overcome the clinical and laboratory challenges of WES and WGS. Further high throughput NGS-based pharmacogenomics studies in different populations and patient settings are necessary to expand knowledge about rare functional variants and to enhance translation in clinical practice.

Vitamin D metabolism in living kidney donors before and after organ donation.

OBJECTIVES: Living kidney donors provide a unique setting to study functional and metabolic consequences after organ donation. Since the lack of data of the homoeostasis of numerous vitamin D metabolites in these healthy subjects, the aim of this study was to assess the vitamin D metabolism before and after kidney donation. METHODS: We investigated the 25-dihydroxyvitamin D2 (25[OH]D2), 25-dihydroxyvitamin D3 (25[OH]D3), 1,25-dihydroxyvitamin D3 (1,25[OH]2D3), 24,25-dihydroxyvitamin D3 (24,25[OH]2D3), 25,26-dihydroxyvitamin D3 (25,26[OH]2D3), and the native vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) in a well characterized study cohort of 32 healthy living kidney donors before and after organ donation. RESULTS: Thirty-two healthy subjects after kidney donation had significantly lower median (interquartile range) 1,25(OH)2D3 serum concentrations (88.6 [62.6-118.8] vs. 138.0 [102.6-152.4] pmol/L, p<0.001) and significantly higher median 25(OH)D2 serum levels (1.80 [1.19-2.19] vs. 1.11 [0.74-1.59] nmol/L, p=0.019) than before donation. Similar serum concentrations of 25(OH)D3 and 25,26(OH)2D3 were observed before and after donation. The 24,25(OH)2D3 blood levels distinctly decreased after organ donation (4.1 [2.3-5.3] vs. 5.3 [2.2-6.9] nmol/L, p=0.153). Native vitamin D2 (0.10 [0.08-0.14] vs. 0.08 [0.06-0.12] nmol/L, p=0.275) was slightly increased and vitamin D3 (1.6 [0.6-7.2] vs. 2.5 [0.9-8.6] nmol/L, p=0.957) decreased after kidney donation. CONCLUSIONS: Living kidney donors were found with decreased 1,25(OH)2D3 and 24,25(OH)2D3, increased 25(OH)D2 and consistent 25(OH)D3 and 25,26(OH)2D3 serum concentrations after organ donation. The current study advances the understanding on vitamin D metabolism suggesting that altered hydroxylase-activities after donation is accompanied by compensatory elevated dietary-related 25(OH)D2 blood concentrations.

Development of a liquid chromatography mass spectrometry method for the determination of vitamin K1, menaquinone-4, menaquinone-7 and vitamin K1-2,3 epoxide in serum of individuals without vitamin K supplements.

OBJECTIVES: Vitamin K and metabolites have a beneficial role in blood coagulation, bone metabolism and growth. However, the determination of vitamin K concentrations in the blood in patients consuming a diet with naturally occurring vitamin K is currently challenging. We aim to develop a cost-effective and rapid method to measure vitamin K metabolites with potential application for clinics and research. METHODS: We developed a simple liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the determination of vitamin K1, menaquinone-4 (MK-4), menaquinone-7 (MK-7) and vitamin K1-2,3 epoxide in human serum and validated the method in a study cohort of 162 patients tested for carbohydrate malabsorption and in 20 patients with oral phenprocoumon intake. RESULTS: The overall precision (CVs) ranged between 4.8 and 17.7% in the specified working range (0.06-9.0 nmol/L for all analytes except for MK-7 with 0.04-6.16 nmol/L). In the malabsorption cohort samples, measured values were obtained for all different vitamin K metabolites except for vitamin K1-2,3 epoxide. This metabolite could be detected only in patients with phenprocoumon intake. The good performance of the method is especially achieved by the interaction of three factors: the use of lipase in the sample preparation, the use of an atypical fluorinated reversed phase column, and a logarithmic methanol gradient. CONCLUSIONS: The described method is able to determine the concentration of four vitamin K metabolites in a time-efficient, simple and cost-effective manner. It can be suitable for both routine clinics and research.

Comparison of two LC-MS/MS methods for the quantification of 24,25-dihydroxyvitamin D3 in patients and external quality assurance samples.

OBJECTIVES: In-house developed liquid-chromatography mass spectrometry (LC-MS/MS) methods are used more and more frequently for the simultaneous quantification of vitamin D metabolites. Among these, 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) is of clinical interest. This study assessed the agreement of this metabolite in two validated in-house LC-MS/MS methods. METHODS: 24,25(OH)2D3 was measured in 20 samples from the vitamin D external quality assurance (DEQAS) program and in a mixed cohort of hospital patients samples (n=195) with the LC-MS/MS method at the Medical University of Graz (LC-MS/MS 1) and at the University of Liège (LC-MS/MS 2). RESULTS: In DEQAS samples, 24,25(OH)2D3 results with LC-MS/MS 1 had a proportional bias of 1.0% and a negative systemic difference of -0.05%. LC-MS/MS 2 also showed a proportional bias of 1.0% and the negative systemic bias was -0.22%. Comparing the EQA samples with both methods, no systemic bias was found (0.0%) and the slope was 1%. The mean difference of 195 serum sample measurements between the two LC-MS/MS methods was minimal (-0.2%). Both LC-MS/MS methods showed a constant bias of 0.31 nmol/L and a positive proportional bias of 0.90%, respectively. CONCLUSIONS: This study is the first to assess the comparability of 24,25(OH)2D3 concentrations in a mixed cohort of hospitalized patients with two fully validated in-house LC-MS/MS methods. Despite different sample preparation, chromatographic separation and ionization, both methods showed high precision measurements of 24,25(OH)2D3. Furthermore, we demonstrate the improvement of accuracy and precision measurements of 24,25(OH)2D3 in serum samples and in the DEQAS program.

Development of a two-dimensional liquid chromatography-tandem mass-spectrometry method for the determination of vitamin D2 in mushrooms.

Different foods, especially mushrooms, are a valuable source of vitamin D2. However, published concentrations in mushrooms show large variabilities. One reason for this is certainly the high biological variability caused by growth conditions, and another could also be found in the analytical methodology. Therefore, this study aimed to develop a sensitive and highly selective two-dimensional liquid chromatography mass spectrometry (LC-MS/MS) method for vitamin D2 analysis in mushrooms. After validation, the method was applied to four different mushroom species. The developed method with a one-step extraction procedure showed a limit of detection of 0.01 µg vitamin D2/g dry mass (DM), a limit of quantification of 0.05 µg vitamin D2/g DM, and recovery rates between 87.6 and 94.8%. The total run time including the re-equilibration of the columns for the next injection was 7.5 min. After adding increased concentrations of pure substance to Pleurotus ostreatus, Lentinula edodes, and brown and white button mushrooms the standard addition plot showed excellent correlation coefficients (R2) of > 0.9994. Mean vitamin D2 concentrations were observed at 0.122 ± 0.007, 0.074 ± 0.005, 0.099 ± 0.007, and 0.073 ± 0.005 µg/g DM. The coefficient of variation (CV) was between 5.1 and 7.6%. This well-optimized, sensitive LC-MS/MS method, with a fast and simple sample preparation and a short run time, can be applied to future studies especially in different mushroom species with variable growing conditions. This will improve our knowledge about the vitamin D2 content in mushrooms.

Considering histamine in functional gastrointestinal disorders.

In westernized countries, adverse reactions to ingested foods are reported to affect up to 20% of the population. Functional, nonspecific, non-allergic gastrointestinal complaints are mainly due to the intolerance/malabsorption of carbohydrates (lactose and fructose), proteins (gluten), and biogenic amines (histamine). Food intolerance/malabsorption is defined by one or several of the above mentioned food components not being degraded and/or absorbed properly within the gastrointestinal tract. Food intolerance/malabsorption causes variable, functional, nonspecific, non-allergic gastrointestinal and extra-intestinal complaints, and a detailed diagnostic workup for all possible etiologic factors in individual patients is essential. Usually, evaluation for histamine intolerance is not included in differential diagnoses of patients with functional, nonspecific, non-allergic gastrointestinal complaints. A targeted dietary intervention for single or possibly combined intolerance/malabsorption is required. In this article, we review currently discussed differential diagnoses and available tests for intolerance/malabsorption. Accordingly, we aim to outline why including histamine and, histamine intolerance, should be considered in differential diagnoses of patients with functional, nonspecific, non-allergic gastrointestinal complaints.

Comparison of the reliability of Gram-negative and Gram-positive flags of the Sysmex UF-5000 with manual Gram stain and urine culture results.

OBJECTIVES: Recently, the fully automated flow cytometry-based UF-5000 (Sysmex Corboration, Kobe, Japan) urine sediment analyzer was developed providing bacteria (BACT) info flags for more accurate bacterial discrimination of urinary tract infections (UTIs). This study aimed to compare the reliability of the UF-5000 BACT-info flags with manual Gram stain and urine culture as the gold standard method. METHODS: A total of 344 urine samples were analyzed on the UF-5000 and compared with manual microscopic Gram stain and urine cultures. Agreement was assessed by Cohen's kappa (κ) analysis. The Youden index was used to determine the optimal BACT and white blood cell (WBC) cut-off points for discriminating positive and negative urine cultures. RESULTS: Overall 98/344 (28.5%) samples were urine culture positive at a cut-off of ≥105 CFU/mL. "Gram-negative?" UF-5000 BACT-Info flags showed a better concordance of 25/40 (62.5%) with urine culture compared to Gram stain with 30/50 (60%). The results for UF-5000 discrimination of Gram-positive and Gram-negative microorganisms demonstrated a substantial (κ = 0.78) and fair (κ = 0.40) agreement with urine culture. Optimal cut-off points detecting positive urine cultures were 135 BACT/µL (sensitivity [SE]: 92.1%, specificity [SP]: 85.4%, positive predictive value [PPV]: 71%, negative predictive value [NPV]: 96%) and 23 WBC/µL (SE: 73.5%, SP: 84.1%, PPV: 65%, NPV: 89%). CONCLUSIONS: The UF-5000 analyzer (Sysmex) is a reliable diagnostic tool for UTI screening. The displayed BACT-Info flags allow a quick diagnostic orientation for the clinician. However, the authors suggest verifying the automated Gram categories with urine culture.

Individual uromodulin serum concentration is independent of glomerular filtration rate in healthy kidney donors.

OBJECTIVES: The mucoprotein uromodulin is considered to correlate with glomerular filtration rates (GFR) in patients with chronic kidney disease (CKD). Here we investigated how serum uromodulin is associated with measured GFR using inulin-clearance and GFR estimated by CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation in healthy subjects. METHODS: We assessed possible correlations between uromodulin serum concentrations, inulin-GFR and CKD-EPI-GFR in a well characterized study cohort of 112 healthy living kidney donors with two kidneys before and 64 with one kidney after kidney donation. A subgroup of 32 individuals, which presented data before and after nephrectomy, was assessed separately. RESULTS: All 112 healthy living kidney donors with two kidneys revealed individual serum uromodulin concentrations between 60.1 and 450.5 µg/L. Sixty-four healthy kidney donors after nephrectomy had significantly lower median (interquartile range) serum uromodulin concentrations (124 [101-166] vs. 185 [152-238] µg/L), inulin-GFR (67.3 [60.6-74.6] vs. 93.5 [82.1-104.4] mL/min/1.73 m2), and CKD-EPI-GFR (61.2 [53.1-69.7] vs. 88.6 [80.0-97.1] mL/min/1.73 m2) as compared to the 112 donors before donation (p<0.001). The subgroup of 32 subjects, which presented data before and after nephrectomy, showed almost the same pattern of kidney function. No statistically relevant associations were found between serum uromodulin and inulin-GFR or CKD-EPI-GFR regarding this healthy population. CONCLUSIONS: These novel findings indicate that - in contrast to patients with CKD - serum uromodulin concentrations are not correlated with measured and estimated GFR in healthy individuals.

Comparison of the diagnostic performance of two automated urine sediment analyzers with manual phase-contrast microscopy.

Background Recently, several manufacturers have launched automated urinalysis platforms. This study aimed to compare the diagnostic performance of the UF-5000 (Sysmex Corporation, Kobe, Japan) and the cobas® u 701 (Roche Diagnostics, Rotkreuz, Switzerland) urine sediment analyzers with manual phase-contrast microscopy as the reference method. Methods A total of 195 urine samples were analyzed on both automated platforms and subjected to manual microscopic examination. Agreement was assessed by Cohen's kappa (κ) analysis. Sensitivities and specificities were calculated. Results The agreement of the UF-5000 with manual microscopy was almost perfect (κ > 0.8) for red (RBC) and white blood cells (WBC), renal tubular epithel cells, hyaline casts, bacteria (BACT) and yeast (YLC), substantial (κ = 0.61-0.80) for squamous epithel cells (SEC) and pathologic casts, and moderate (κ = 0.41-0.60) for transitional epithel cells. The cobas® u 701 showed substantial agreement (κ = 0.61-0.80) for WBC, moderate agreement (κ = 0.41-0.60) for hyaline casts, and fair agreement (κ = 0.21-0.40) for RBC, SEC, non-squamous epithel (NEC), pathologic casts, BACT and YLC. The UF-5000 sensitivities ranged between 98.5% for RBC and 83.3% for pathological casts. The cobas® u 701 showed sensitivities between 83.0% for WBC and 31.6% for YLC. Conclusions The UF-5000 (Sysmex) analyzer showed a better diagnostic agreement with manual phase-contrast microscopy compared to the cobas® u 701 (Roche) module. The Sysmex platform showed reliable results for urine sediment analysis. However, pathological samples should be verified with manual microscopy.

Determination of Trimethylamine-N-oxide by a Simple Isocratic High-Throughput Liquid-Chromatography Tandem Mass-Spectrometry Method.

BACKGROUND: As trimethylamine-N-oxide (TMAO) is considered to be associated with various diseases, rapid determination of serum TMAO concentration is of clinical interest. This study is aimed at evaluating the analytical performance of a simple isocratic liquid chromatography-tandem mass-spectrometry (LC-MS/MS) method for TMAO quantification. METHODS: TMAO measurements were performed on a tandem mass spectrometer, SCIEX QTRAP 4500 (Applied Biosystems, Framingham, MA, USA), coupled with an Agilent 1260 Infinity HPLC system (Agilent Technologies, Santa Clara, CA, USA). The separation was performed on a Hypercarb Porus Grahitic Carbon (PGC) column (ThermoFisher Scientific, Waltham, MA, USA) by isocratic elution mode. Linearity, precision, recovery, and pre-analytical requirements of the TMAO LC-MS/MS method were evaluated. The imprecision acceptance criteria were defined 15%. We investigated sample stability at room temperature (RT) and assessed the serum TMAO concentrations of 188 healthy adults. RESULTS: The TMAO LC-MS/MS method was linear over the concentration range of 0.5 - 80 µmol/L. Intra- and inter-day precision ranged between 2.24 - 3.37% and 6.95 - 9.97%, recovery between 106 - 114%, respectively. At RT, serum samples were stable for 8 days. The median serum TMAO concentration of 188 healthy adults was 2.27 µmol/L (2.5th and 97.5th percentile: 0.75 - 10.46 µmol/L), respectively. CONCLUSIONS: The isocratic TMAO LC-MS/MS shows a broad analytical range and meets the imprecision acceptance criteria of 15%. This method is a robust and reliable diagnostic tool for the assessment of the human TMAO status. Serum samples are stable at RT for at least 8 days.

Iron status determination in individuals with Helicobacter pylori infection: conventional vs. new laboratory biomarkers.

Background Helicobacter pylori has been associated with iron deficiency (ID). This study is aimed at investigating ID with conventional (ferritin, transferrin saturation [TSAT]) and new biomarkers (soluble transferrin receptor [sTfR], sTfR/log ferritin, reticulocyte hemoglobin content [CHr], hepcidin-25) in patients sub-grouped by the presence or absence of H. pylori infection. Methods In total, 200 consecutive outpatients, who were referred for the H. pylori 13C-urea breath test (13C-UBT), underwent blood testing for ID. Additionally, Thomas-plot (TP)-analyses (sTfR/log ferritin, CHr) were calculated. Results Fifty-three and 147 individuals were found with and without H. pylori infection, respectively. Patients with H. pylori infection showed a higher sTfR concentration (p<0.02) and a higher sTfR/log ferritin ratio (p<0.05). Based on a ferritin <30 µg/L and/or a TSAT <20%, 25/53 (47.2%) patients with H. pylori infection and 63/147 (42.9%) without H. pylori infection showed ID. Based on TP-analyses, 10/53 (18.9%) patients with and 17/147 (11.6%) without H. pylori infection were identified with ID. Completed eradication therapy tended to be associated with functional ID. Conclusions Helicobacter pylori infection was associated with significantly higher plasma sTfR concentrations and sTfR/log ferritin ratios. Patients with H. pylori eradication therapy were more often detected with functional ID compared to patients without eradication therapy, when using the new biomarkers.

Clinical and genetic heterogeneity in a large cohort of Armenian patients with late-onset familial Mediterranean fever.

PURPOSE: This work aimed at investigating demographic, clinical, and genetic characteristics of individuals experiencing their first familial Mediterranean fever (FMF) attack at age ≥40 years in a very large cohort of Armenian FMF patients. METHODS: In total, 10,370 Armenian patients diagnosed with FMF based on the Tel Hashomer criteria and carrying at least one MEFV mutant allele were included in this study. RESULTS: A total of 354 (3.40%) patients had late-onset FMF. Of these, 194 (54.80%) were female and 160 (45.20%) were male. The following genotypes were significantly associated with the late-onset variant: M680I/E148Q (P = 0.004), M694V/E148Q (P < 0.001), and V726A/V726A (P< 0.001). Of note, 12/354 (3.40%) patients were found to be homozygous for the M694V mutation. Individuals with late-onset FMF had a milder disease phenotype presenting significantly less frequent fever, skin manifestation, and chest pain compared to individuals with a disease onset before 40 years of age. Abdominal pain was found more often in the late-onset FMF group, whereas arthritis, proteinuria, and amyloidosis did not differ significantly between the two groups. CONCLUSION: Our data suggest that late-onset FMF is more prevalent in women and is of greater clinical as well as genetic heterogeneity than previously reported.

Prospective cohort studies of beta-trace protein and mortality in haemodialysis patients and patients undergoing coronary angiography.

Background: Beta-trace protein (BTP) is a low-molecular-weight glycoprotein, which may serve as an endogenous biomarker of kidney function and cardiovascular risk. Methods: We examined cardiovascular and all-cause mortality according to BTP concentrations in 2962 individuals referred for coronary angiography from the Ludwigshafen Risk and Cardiovascular Health study and in 907 patients with Type 2 diabetes mellitus undergoing haemodialysis from the German Diabetes and Dialysis (4D) study. Results: Haemodialysis patients had considerably higher median (interquartile range) BTP concentrations [6.00 (4.49-7.96) mg/L] and experienced a 4-fold increased mortality rate compared with coronary angiography patients [BTP concentration: 0.55 (0.44-0.67) mg/L]. After adjustment for age, sex, cardiovascular risk factors and creatinine, 4D patients in the highest quartile (>7.96 mg/L) had a 1.6-fold increased rate of all-cause mortality [hazard ratio (HR) 1.62, 95% confidence interval (CI) 1.19-2.20] compared with the lowest quartile (<4.49 mg/L) (P = 0.002) In patients undergoing coronary angiography, the adjusted HRs (95% CI) for all-cause and cardiovascular mortality were 1.23 (1.0-1.51) and 1.27 (0.99-1.63) in the highest (>0.67 mg/L) compared with the lowest (<0.44 mg/L) quartile (P = 0.043 and 0.062). In both cohorts, the BTP/creatinine ratio was a stronger predictor of all-cause and cardiovascular mortality compared with BTP. Conclusion: BTP was associated with all-cause mortality independently of renal function in haemodialysis patients. The BTP/creatinine ratio was more predictive for all-cause and cardiovascular mortality in haemodialysis patients and individuals referred for angiography compared with BTP as single marker.

Non-celiac gluten sensitivity: people without celiac disease avoiding gluten-is it due to histamine intolerance?

INTRODUCTION: Food intolerance/malabsorption is caused by food ingredients, carbohydrates (mainly lactose and fructose), proteins (gluten), and biogenic amines (histamine) which cause nonspecific gastrointestinal and extra-intestinal symptoms. Here we focus on possible etiologic factors of intolerance/malabsorption especially in people with non-celiac gluten sensitivity (NCGS) or the so-called people without celiac disease avoiding gluten (PWCDAG) and histamine intolerance. METHODS: Recognizing the recently described symptoms of NCGS (PWCDAG) we review correlations and parallels to histamine intolerance (HIT). RESULTS: We show that intestinal and extra-intestinal NCGS (PWCDAG) symptoms are very similar to those which can be found in histamine intolerance. CONCLUSIONS: After a detailed diagnostic workup for all possible etiologic factors in every patient, a targeted dietary intervention for single or possibly combined intolerance/malabsorption might be more effective than a short-term diet low in fermentable oligo-, di- and monosaccharides and polyols (FODMAP) or the untargeted uncritical use of gluten-free diets.