Glycated albumin in pregnancy: LC-MS/MS-based reference interval in healthy, nulliparous Scandinavian women and its diagnostic accuracy in gestational diabetes mellitus

Glycated albumin (GA) may be a useful biomarker of glycemia in pregnancy. The aim of this study was to establish the reference interval (RI) for GA, analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), in healthy, nulliparous pregnant women. In addition, we assessed the accuracy of GA and glycated hemoglobin A1c (HbA1c) in the diagnosis of gestational diabetes mellitus (GDM). Finally, we explored the prevalence of GDM in healthy nulliparas, comparing three diagnostic guidelines (WHO-1999, WHO-2013 and the Norwegian guideline). The study was carried out at Stavanger University Hospital, Norway, and included a study population of 147 pregnant nulliparous women. An oral glucose tolerance test (OGTT) was performed and used as the gold standard for GDM diagnosis. Blood samples for analysis of GA and HbA1c were collected at pregnancy week 24–28. A nonparametric approach was chosen for RI calculation, and receiver operating characteristic (ROC) curves were used to evaluate the diagnostic performance of GA and HbA1c. The established RI for GA in 121 pregnant women was 7.1–11.6%. The area under the ROC curves (AUCs) were 0.531 (GA) and 0.627 (HbA1c). According to the WHO-1999, WHO-2013 and the Norwegian guideline, respectively, 24 (16%), 36 (24%) and 21 (14%) women were diagnosed with GDM. Only nine women (6%) fulfilled the GDM-criteria of all guidelines. In conclusion, we established the first LC-MS/MS-based RI for GA in pregnant women. At pregnancy weeks 24–28, neither GA nor HbA1c discriminated between those with and without GDM. Different women were diagnosed with GDM using the three guidelines.publishedVersio

Hepcidin analysis in pneumonia: Comparison of immunoassay and LC-MS/MS

Background The iron-regulatory hormone hepcidin is a promising biomarker to differentiate anaemia of inflammation from iron deficiency. Plasma hepcidin concentrations increase substantially during inflammation, and the amount of smaller, non-biologically active isoforms of hepcidin increase in inflammatory conditions. These smaller isoforms are measured in some, but not all analytical methods. Thus, we evaluated the comparability of two analytical methods with different isoform selectivity during and after acute-phase pneumonia as a highly inflammatory model disease. Methods Blood samples from a cohort of 267 hospitalized community-acquired pneumonia patients collected at admission and a 6-week follow-up were analysed. Hepcidin was measured in plasma by an immunoassay, which recognizes all hepcidin isoforms, and a liquid chromatography tandem mass spectrometry (LC-MS/MS), which selectively measures the bioactive hepcidin-25. Additionally, a subset of serum samples was analysed by LC-MS/MS. Results Hepcidin measurements by immunoassay were higher compared with LC-MS/MS. The relative mean difference of hepcidin plasma concentrations between the two analytical methods was larger in admission samples than in follow-up samples (admission samples 200 ng/mL: 78%, follow-up samples >10 ng/mL: 22%). During acute-phase pneumonia, serum concentrations were on average 22% lower than plasma concentrations when measured by LC-MS/MS. Conclusions Immunoassay measured higher hepcidin concentrations compared with LC-MS/MS, with more pronounced differences in high-concentration samples during acute-phase pneumonia. These findings should be considered in local method validations and in future harmonization and standardization optimization of hepcidin measurements.publishedVersio

Glycated albumin and continuous glucose monitoring metrics across pregnancy in women with pre-gestational diabetes

Introduction: Glycated albumin (GA), a biomarker reflecting short-term glycaemia, may be useful to assess glycaemic control in pregnancy. We examined the association between GA and continuous glucose monitoring (CGM) metrics across gestation. Methods: In this prospective cohort study including 40 women with pre-gestational diabetes, blood samples for analysis of GA and glycated haemoglobin A1c (HbA1c) were collected at pregnancy week 12, 20, 24, 28, 32 and 36. In the CGM-group (n = 19), CGM data were collected from first trimester until pregnancy week 36. Receiver operating characteristic (ROC) curves were used to assess the accuracy of GA and HbA1c to detect poor glycaemic control, using CGM metrics as the reference standard. This study was conducted at Stavanger University Hospital, Norway, in 2016–2018. Results: Glycaemic control improved across gestation with more time spent in target range, coinciding with decreased glycaemic variability and lower mean GA level. There was statistically significant correlation between GA and most CGM metrics. The area under the ROC curves (AUC) for detecting time in range 25% for the pregnancy glucose target 63–140 mg/dl (3.5–7.8 mmol/L) were 0.78 and 0.82 for GA, whereas AUCs of 0.60 and 0.72 were found for HbA1c, respectively. Conclusions: Higher GA levels were associated with less time spent in target range, more time spent in the above range area and increased glycaemic variability. GA was more accurate than HbA1c to detect time above range >25% and time in range <70%.publishedVersio

High-Sensitivity Cardiac Troponin I and T Response Following Strenuous Activity is Attenuated by Smokeless Tobacco: NEEDED (North Sea Race Endurance Exercise Study) 2014

Background Use of snus, a smokeless tobacco product, is increasing in Scandinavia. Strenuous physical activity is associated with an acute increase in high‐sensitivity cardiac troponin (swhs‐cTn) concentrations. Current smoking is associated with lower hs‐cTn, but whether this also holds true for smokeless tobacco and whether tobacco affects the hs‐cTn response to exercise remain unknown. Methods and Results We measured hs‐cTnI and hs‐cTnT concentrations in 914 recreational athletes before and 3 and 24 hours after a 91‐km bicycle race. Self‐reported snus tobacco habits were reported as noncurrent (n=796) and current (n=118). The association between snus use and change in log‐transformed hs‐cTnI and hs‐cTnT concentrations (ie, the differences between concentrations at baseline and 3 hours and 24 hours ) were assessed by multivariable linear regression analysis. Concentrations of hs‐cTn at baseline were lower in current than in noncurrent snus users (hs‐cTnI median, 1.7 ng/L; Q1 to Q3: 1.6–2.3 versus 2.0 ng/L; Q1 to Q3: 1.6–3.2 [P=0.020]; and hs‐cTnT: median, 2.9 ng/L, Q1 to Q3: 2.9–3.5 versus 2.9 ng/L, Q1 to Q3: 2.9–4.3 [P=0.021]). In fully adjusted multivariable models, use of snus was associated with lower change in hs‐cTn concentrations from baseline to 3 hours (hs‐cTnI: −29% [P=0.002], hs‐cTnT: −18% [P=0.010]) and 24 hours (hscTnI: −30% [P=0.010], hs‐cTnT −19%, [P=0.013]). Conclusions Resting hs‐cTn concentrations are lower and the exercise‐induced cardiac troponin response is attenuated in current users of smokeless tobacco compared with nonusers. Further insight into the pathophysiological processes underlying the attenuated cardiac troponin response to exercise in tobacco users is needed.publishedVersio

Haplotype analysis of Norwegian and Swedish patients with acute intermittent porphyria (AIP): Extreme haplotype heterogeneity for the mutation R116W

Abstract. Acute intermittent porphyria (AIP), the most common of the acute porphyrias, is caused by mutations in the gene encoding hydroxymethylbilane synthase (HMBS) also called porphobilinogen deaminase (PBGD). The mutation spectrum in the HMBS gene is characterized by a majority of family specific mutations. Among the exceptions are R116W and W198X, with high prevalence in both the Dutch and Swedish populations. These two mutations were also detected in unrelated Norwegian patients. Thus, Norwegian and Swedish patients were haplotyped using closely linked flanking microsatellites and intragenic single nucleotide polymorphisms (SNPs) to see if the high frequency of these two mutations is due to a founder effect. Twelve intragenic SNPs were determined by a method based on fluorescent restriction enzyme fingerprinting single-strand conformation polymorphism (F-REF-SSCP). W198X occurred exclusively on one haplotype in both Norwegian and Swedish patients, showing that it has originated from a common gene source. In contrast, R116W was found on three different haplotypes in three Norwegian families, and in five Swedish families on four or five haplotypes. This extreme haplotype heterogeneity indicates that R116W is a recurrent mutation, maybe explained by the high mutability of CpG dinucleotides. This can also explain why it is the only AIP mutation reported to occur in seven different populations (Norway

Klotho and Fibroblast Growth Factor 23 Are Independent of Vitamin D, and Unlike Vitamin D, Are Not Associated With Graft- and Patient Survival After Kidney Transplantation

Background: Short-term survival after kidney transplantation is excellent but long-term survival remains suboptimal. The aim of the study was to explore the relationship between soluble α-Klotho (sKlotho) and intact fibroblast growth factor 23 (iFGF23) measured 8 wk and 1 y posttransplant with long-term graft- and patient survival in a cohort of kidney transplant recipients with deficient and nondeficient vitamin D (25[OH]D) levels. Methods: Vitamin D, sKlotho, and iFGF23 were measured 8 wk and 1 y posttransplant in 132 recipients transplanted between November 2012 and October 2013. Results: Of the 132 kidney transplant recipients, 49 had deficient vitamin D levels (<30 nmol/L) and 83 had nondeficient vitamin D levels (≥30 nmol/L) at 8 wk posttransplant. The mean age was 51 y and the median follow-up was 7.4 y. At 1 y posttransplant, vitamin D increased significantly. There were no significant differences in sKlotho or iFGF23 levels between the 2 vitamin D groups neither at 8 wk nor 1 y. sKlotho increased significantly and iFGF23 decreased significantly in the whole cohort. During the follow-up, there were 36 graft losses (27%) and 27 deaths (20%). Ninety-four percent of the transplant recipients with nondeficient vitamin D levels were alive with a well-functioning graft after 5 y using Kaplan-Meier survival estimates, compared with 84% of the patients with deficient vitamin D levels (P = 0.014). Klotho and FGF23 levels did not influence graft- and patient survival. Conclusions: In this nationwide cohort of kidney transplant recipients, long-term graft- and patient survival were significantly better in patients with vitamin D ≥30 nmol/L 8 wk posttransplant compared with those with vitamin D <30 nmol/L. sKlotho levels increased and iFGF23 levels decreased from 8 wk to 1 y posttransplant. Klotho and FGF23 levels were not associated with graft- and patient survival.publishedVersio

The relationship between Fibroblast Growth Factor 23 (FGF23) and cardiac MRI findings following primary PCI in patients with acute first time STEMI

Background Fibroblast growth factor 23 (FGF23) is a regulator of mineral metabolism, that has been linked to myocardial remodeling including development of left ventricular (LV) hypertrophy and myocardial fibrosis. The aim of this study was to investigate the relationship between intact FGF23 (iFGF23), myocardial infarct size and LV remodeling following a first acute ST-elevation myocardial infarction (STEMI). Methods and results Forty-two consecutive patients with first-time STEMI, single vessel disease, successfully treated with primary percutaneous coronary intervention were included. Cardiac magnetic resonance (CMR) imaging was performed at day 2, 1 week, 2 months and 1 year post MI, and blood samples were drawn at admittance and at the same time points as the CMRs. The cohort was divided according to the presence or not of heart failure post MI. In the total cohort, iFGF23 (mean ± SD) was significantly lower at day 0 (33.7 ± 20.6 pg/ml) and day 2 (31.5 ± 23.4 pg/ml) compared with a reference interval based on 8 healthy adults (43.9 pg/ml ± 19.0 pg/ml). iFGF23 increased to normal levels (55.8 ± 23.4 pg/ml) seven days post MI. In the subset of patients with signs of acute heart failure, FGF23 was higher at all measured timepoints, reaching significantly higher FGF23 levels at 2 months and 1 year following revascularization. Conclusion There was a reduction in iFGF23 levels during the acute phase of MI, with a normalization at seven days following revascularization. During one-year follow-up, there was a gradual increase in iFGF23 levels in patients with heart failure.publishedVersio

Occult obstructive coronary artery disease is associated with prolonged cardiac troponin elevation following strenuous exercise

Background Sudden cardiac death among middle-aged recreational athletes is predominantly due to myocardial ischaemia. This study examined whether measuring cardiac troponin I and T (cTnI and cTnT) after strenuous exercise could identify occult obstructive coronary artery disease. Design Prospective observational study. Methods Subjects were recruited from 1002 asymptomatic recreational cyclists completing a 91-km mountain bike race (North Sea Race Endurance Exercise Study). No subject had known cardiovascular disease or took cardiovascular medication. Blood samples were collected within 24 h before and 3 h and 24 h after the race. Coronary computed tomography angiography was performed in 80 participants with the highest post-exercise cTnI and in 40 reference subjects with moderately elevated cTnI values. Results Study subjects (N = 120) were 45 (36–52) years old and 74% were male. There were similar demographics in the High-cTnI group and the Reference group. The cTn concentrations were highest at 3 h post-race: cTnI, 224 (125–304) ng/L; cTnT, 89 (55–124) ng/L. Nine subjects had obstructive coronary artery disease on coronary computed tomography angiography, eight of whom were High-cTnI responders. Two subjects had myocardial bridging, both High-cTnI responders. Troponin concentrations at 24 h post-race were higher in subjects with obstructive coronary artery disease than in the rest of the cohort (n = 109): cTnI, 151 (72–233) ng/L vs. 24 (19–82) ng/L, p = 0.005; cTnT, 39 (25–55) ng/L vs. 20 (14–31) ng/L, p = 0.002. The areas under the receiver operating characteristic curves for predicting obstructive coronary artery disease were 0.79, p = 0.005 (cTnI) and 0.82, p = 0.002 (cTnT). Conclusion In subjects with occult obstructive coronary artery disease there was a prolonged elevation of cTn following strenuous exercise.acceptedVersio

Duration of elevated heart rate Is an important predictor of exercise-induced troponin elevation

Background The precise mechanisms causing cardiac troponin (cTn) increase after exercise remain to be determined. The aim of this study was to investigate the impact of heart rate (HR) on exercise‐induced cTn increase by using sports watch data from a large bicycle competition. Methods and Results Participants were recruited from NEEDED (North Sea Race Endurance Exercise Study). All completed a 91‐km recreational mountain bike race (North Sea Race). Clinical status, ECG, blood pressure, and blood samples were obtained 24 hours before and 3 and 24 hours after the race. Participants (n=177) were, on average, 44 years old; 31 (18%) were women. Both cTnI and cTnT increased in all individuals, reaching the highest level (of the 3 time points assessed) at 3 hours after the race (P150 beats per minute was a significant predictor of both cTnI and cTnT, at both 3 and 24 hours after exercise. Neither mean HR nor mean HR in percentage of maximum HR was a significant predictor of the cTn response at 3 and 24 hours after exercise. Conclusions The duration of elevated HR is an important predictor of physiological exercise‐induced cTn elevation.publishedVersio

Endurance exercise training volume is not associated with progression of coronary artery calcification

Background Recent cross‐sectional studies have suggested a dose‐dependent relationship between lifelong exposure to physical activity and the burden of calcified coronary artery disease (CAD). No longitudinal studies have addressed this concern. Hypothesis Exercise volume is associated with progression of coronary artery calcium (CAC), defined as ≥10 units increase in CAC score. Methods Sixty‐one recreational athletes who were assessed by coronary computed tomography angiography (CCTA) as part of the NEEDED 2013/14 study were re‐assessed 4‐5 years later, in 2018. Results Subjects were 45.9 ± 9.6 years old at inclusion, and 46 (74%) were male. Between 2013 and 2018, the participants reported median 5 (range: 0‐20, 25th‐75th percentile: 4‐6) hours of high‐intensity exercise per week. None of the included subjects smoked during follow‐up. At inclusion, 21 (33%) participants had coronary artery calcifications. On follow‐up CCTA in 2018, 15 (25%) subjects had progressive coronary calcification (≥10 Agatston units increase in CAC). These subjects were older (53 ± 9 vs 44 ± 9 years old, P = .002) and had higher levels of low‐density lipoprotein at baseline (3.5 (2.9‐4.3) vs 2.9 (2.3‐3.5) mmol/L, P = .031) as compared to subjects with stable condition. No relationship was found between hours of endurance training per week and progression of coronary artery calcification. In multiple regression analysis, age and baseline CAC were the only significant predictors of progressive CAC. Conclusion No relationship between exercise training volume and the progression of coronary artery calcification was found in this longitudinal study of middle‐aged recreational athletes.publishedVersio