Relationship between high-sensitivity cardiac troponin I and blood pressure among young and healthy adults

BACKGROUND

The aim of this study was to evaluate the relationship of cardiac troponin (cTn) levels with conventional and ambulatory blood pressure (BP) in young and healthy adults.

METHODS

We performed a population based cross-sectional analysis among 2,072 young and healthy adults aged 25-41 years free of cardiovascular disease and diabetes mellitus. cTnI was measured using a highly sensitive (hs) assay. The relationships of high sensitivity cardiac tropononin I (hs-cTnI) with office and 24-hour BP were assessed using multivariable regression analyses.

RESULTS

Median age was 37 years and 975 (47%) participants were male. hs-cTnI levels were detectable in 2,061 (99.5%) individuals. Median (interquartile range) hs-cTnI levels were 0.98 (0.71; 1.64) ng/L among men and 0.48 (0.33; 0.71) ng/L among women. Systolic BP, but not diastolic BP, gradually increased across hs-cTnI quartiles (118, 120, 121, and 122 mm Hg for conventional BP; P = 0.0002; 122, 123, 124, and 124 mm Hg for 24-hour BP, P = 0.0001). In multivariable linear regression analyses, the β estimates for systolic BP per 1-unit increase in log transformed hs-cTnI were 2.52 for conventional BP (P = 0.0001); 2.75 for 24-hour BP (P < 0.0001); 2.71 and 2.41 (P < 0.0001 and P = 0.0002) for day and nighttime BP, respectively. There was a significant relationship between hs-cTnI and the Sokolow-Lyon Index (odds ratio (95% confidence interval): 2.09 (1.37; 3.18), P < 0.001).

CONCLUSION

Using a hs assay, hs-cTnI was detectable in virtually all participants of a young and healthy population. hs-cTnI was independently associated with systolic BP and left ventricular hypertrophy.

Symptomorientierte Notfalldiagnostik im Praxislabor

Laborparameter des Praxislabors erlauben unter anderem eine effiziente Versorgung von Patienten, welche sich mit akuten Problemen in der Grundversorgungspraxis melden. Mittels einer qualitätsgesicherten Analytik ist es möglich, zusammen mit klinischen Informationen das Risiko für das Vorhandensein einer Erkrankung (Nachtestwahrscheinlichkeit) zu schätzen. Man muss dabei gleichsam die Charakteristika des eingesetzten Tests als auch die Vortestwahrscheinlichkeit eines Patienten kennen, um eine Erkrankung ein- oder auszuschließen. Für die Schätzung der Vortestwahrscheinlichkeit ist die klinische Risikostratifizierung essentiell. Je nach Verdachtsdiagnose stehen zudem auch validierte Risiko-scores zur Verfügung. Im vorliegenden Artikel werden die Grundlagen des Bayes Theorem zusammen mit einer klinischen Anwendung in Notfallszenarien vorgestellt. Diese umfassen den Gebrauch von D-Dimer beim Ausschluss von thromboembolischen Erkrankungen, den Einsatz des Gruppe A Streptokokken-Schnelltests bei der akuten Pharyngitis, sowie die Wertigkeit der Troponin-Diagnostik beim Thoraxschmerz, des Entzündungsmarkers CRP bei Verdacht auf Pneumonie, und des Streifentests im Harn bei Verdacht auf Harnwegsinfekt. Diese Beispiele illustrieren, dass die Durchführung einer Risikostratifizierung von Patienten die Basis ist, um die Wertigkeit der im Praxislabor erhaltenen Resultate für den Nachweis und Ausschluss von Erkrankungen wirkungsvoll zu erhöhen.

Glucagon-like peptide-1 and blood pressure in young and healthy adults from the general population

Hypertension and diabetes mellitus are highly correlated, but the underlying mechanisms are only partly understood. Therefore, the aim of our study was to investigate the relationships between plasma levels of glucagon-like peptide-1, a key factor in the regulation of glucose homeostasis, and various blood pressure indices. Healthy adults aged 25 to 41 years were enrolled in a population-based study. Established cardiovascular disease, diabetes mellitus, or a body mass index >35 kg/m(2) were exclusion criteria. Fasting plasma glucagon-like peptide-1 levels as determined with a novel high-sensitive assay and ambulatory blood pressure data were available in 1479 participants not using antihypertensive treatment. Median age of our population was 38 years. Mean systolic and diastolic blood pressure across increasing glucagon-like peptide-1 quartiles were 120.6, 122.8, 123.2, and 124.9 mm Hg and 77.1, 78.7, 78.9, and 79.9 mm Hg, respectively. We found a linear relationship of glucagon-like peptide-1 with 24-hour ambulatory blood pressure after multivariable adjustment (β per 1 log-unit increase 2.01; 95% confidence interval, 1.02-3.00; P<0.0001 for systolic and 1.22; 0.47-1.97; P=0.002 for diastolic blood pressure). In separate analyses, glucagon-like peptide-1 was significantly related to both awake (β per 1 log-unit increase 2.05; 1.02-3.09; P=0.0001 for systolic and 1.15; 0.35-1.96; P=0.005 for diastolic blood pressure) and asleep blood pressure (β per 1 log-unit increase 1.34; 0.26-2.42; P=0.01 for systolic and 1.05; 0.26-1.84; P=0.009 for diastolic blood pressure). In conclusion, plasma levels of glucagon-like peptide-1 are significantly associated with both systolic and diastolic blood pressure levels.

Chronobiology and circadian rhythms establish a connection to diagnosis

Circadian rhythms are synchronized by the light/dark (L/D) cycle over the 24-h day. A suprachiasmatic nucleus in the hypothalamus governs time keeping based on melanopsin messages from the retina in the eyes and transduces regulatory signals to tissues through an array of hormonal, metabolic and neural outputs. Currently, vague impressions on circadian regulation in health and disease are replaced by scientific facts: in addition to L/D cyling, oscillation is maintained by genetic (

Age-specific differences between conventional and ambulatory daytime blood pressure values

Mean daytime ambulatory blood pressure (BP) values are considered to be lower than conventional BP values, but data on this relation among younger individuals <50 years are scarce. Conventional and 24-hour ambulatory BP were measured in 9550 individuals not taking antihypertensive treatment from 13 population-based cohorts. We compared individual differences between daytime ambulatory and conventional BP according to 10-year age categories. Age-specific prevalences of white coat and masked hypertension were calculated. Among individuals aged 18 to 30, 30 to 40, and 40 to 50 years, mean daytime BP was significantly higher than the corresponding conventional BP (6.0, 5.2, and 4.7 mm Hg for systolic; 2.5, 2.7, and 1.7 mm Hg for diastolic BP; all P<0.0001). In individuals aged 60 to 70 and ≥70 years, conventional BP was significantly higher than daytime ambulatory BP (5.0 and 13.0 mm Hg for systolic; 2.0 and 4.2 mm Hg for diastolic BP; all P<0.0001).The prevalence of white coat hypertension exponentially increased from 2.2% to 19.5% from those aged 18 to 30 years to those aged ≥70 years, with little variation between men and women (8.0% versus 6.1%; P=0.0003). Masked hypertension was more prevalent among men (21.1% versus 11.4%; P<0.0001). The age-specific prevalences of masked hypertension were 18.2%, 27.3%, 27.8%, 20.1%, 13.6%, and 10.2% among men and 9.0%, 9.9%, 12.2%, 11.9%, 14.7%, and 12.1% among women. In conclusion, this large collaborative analysis showed that the relation between daytime ambulatory and conventional BP strongly varies by age. These findings may have implications for diagnosing hypertension and its subtypes in clinical practice.

Oxidative stress in hypobaric hypoxia and influence on vessel-tone modifying mediators

Increased pulmonary artery pressure is a well-known phenomenon of hypoxia and is seen in patients with chronic pulmonary diseases, and also in mountaineers on high altitude expedition. Different mediators are known to regulate pulmonary artery vessel tone. However, exact mechanisms are not fully understood and a multimodal process consisting of a whole panel of mediators is supposed to cause pulmonary artery vasoconstriction. We hypothesized that increased hypoxemia is associated with an increase in vasoconstrictive mediators and decrease of vasodilatators leading to a vasoconstrictive net effect. Furthermore, we suggested oxidative stress being partly involved in changement of these parameters. Oxygen saturation (Sao2) and clinical parameters were assessed in 34 volunteers before and during a Swiss research expedition to Mount Muztagh Ata (7549 m) in Western China. Blood samples were taken at four different sites up to an altitude of 6865 m. A mass spectrometry-based targeted metabolomic platform was used to detect multiple parameters, and revealed functional impairment of enzymes that require oxidation-sensitive cofactors. Specifically, the tetrahydrobiopterin (BH4)-dependent enzyme nitric oxide synthase (NOS) showed significantly lower activities (citrulline-to-arginine ratio decreased from baseline median 0.21 to 0.14 at 6265 m), indicating lower NO availability resulting in less vasodilatative activity. Correspondingly, an increase in systemic oxidative stress was found with a significant increase of the percentage of methionine sulfoxide from a median 6% under normoxic condition to a median level of 30% (p<0.001) in camp 1 at 5533 m. Furthermore, significant increase in vasoconstrictive mediators (e.g., tryptophan, serotonin, and peroxidation-sensitive lipids) were found. During ascent up to 6865 m, significant altitude-dependent changes in multiple vessel-tone modifying mediators with excess in vasoconstrictive metabolites could be demonstrated. These changes, as well as highly significant increase in systemic oxidative stress, may be predictive for increase in acute mountain sickness score and changes in Sao2.

Prevalence of vitamin B(12) depletion and deficiency in Liechtenstein

OBJECTIVE

Data about vitamin B(12) (B(12)) deficiency in the general population are scarce. The present study was performed to determine the prevalence of B(12) deficiency in the general population of the Principality of Liechtenstein, as well as to identify sub-populations potentially at high risk.

DESIGN

Retrospective study.

SETTING

Ambulatory setting, population of the Principality of Liechtenstein.

SUBJECTS

Seven thousand four hundred and twenty-four patients seeking medical attention whose serum samples were referred for routine work-up in an ambulatory setting were consecutively enrolled. Serum total B(12) was determined in all patients in this cohort. In addition, for a subgroup of 1328 patients, serum holotranscobalamin was also measured. Prevalence of B(12) deficiency was calculated. Further, multivariate logistical regression models were applied to identify covariates independently associated with B(12) deficiency and depletion.

RESULTS

Nearly 8% of the general population was suffering from either B(12) depletion or deficiency. The ratio between B(12) depletion and deficiency was 2:1 for all age ranges. Pathological changes were detected predominantly in older people. Female gender was a significant predictor of B(12) depletion. In the cohort, nearly 40% exhibited either depletion or deficiency of B(12).

CONCLUSIONS

B(12) depletion and deficiency are common in Liechtenstein, a Central European country. The measurement of biochemical markers represents a cost-efficient and valid assessment of the B(12) state. When a deficiency of B(12) is diagnosed at an early stage, many cases can be treated or prevented, with beneficial effects on individual outcomes and subsequent potential reductions in health-care costs.

Anti-red blood cell antibodies, free light chains, and antiphospholipid antibodies in intravenous immunoglobulin preparations

BACKGROUND

Anti-red blood cell antibodies, free light chains (FLC) and prothrombotic proteins (PTP) may co-elute with intact immunoglobulin (IgG), and may be the cause of adverse reactions to intravenous immunoglobulin preparations (IVIG).

OBJECTIVES

To investigate the presence of residual amounts of these components in IVIG and their effects on ABO blood group agglutination.

METHODS

Iso-agglutinin anti-A and anti-B activity was determined with a direct hemagglutination assay of red blood cell (RBC) suspensions from 1% of 46 blood donors together with the serial dilutions of five IVIG (IV1, IV2, IV3, IV4, IV5). Anti-A1 monoclonal antibody was used to confirm reactivity with the A1-reference RBC. The selected IVIG were diluted to a final concentration of 25 mg/ml in 0.15 M NaCI and 0.01 M phosphate-buffered saline, pH 7.4, with or without a further twofold dilution in a low ionic strength solution.

RESULTS

A variation up to fivefold in the titer strength of anti-A/B activity was observed between the IVIG preparations. A2-type RBC required higher IVIG inputs when tested in 0.15 M NaCl. The differences in FLC kappa and lambda concentrations were as high as > 400 mg/L among the various IVIG. Only IV1 had a significantly high level of antiphospholipid IgG antibodies (18 U/ml). We demonstrated the presence of anti-RBC antibodies, FLC and PTP in IVIG preparations.

CONCLUSIONS

Our findings provide clear evidence that IVIG may harbor pathophysiological substrates with a potential risk for adverse effects such as iatrogenic hemolysis, FLC-associated disorders, and thromboembolism.

Serum concentrations of 25-hydroxyvitamin D and immunoglobulins in an older Swiss cohort: results of the Senior Labor Study

BACKGROUND

Vitamin D and the components of humoral immunity play important roles in human health. Older people have lower 25-hydroxyvitamin D (25(OH)D) serum levels than younger adults. We aimed to determine the levels of 25(OH)D serum concentrations in healthy senior citizens and to study their relationship to the levels of components of humoral immunity.

METHODS

A total of 1,470 healthy Swiss men and women, 60 years or older, were recruited for this study. A total of 179 subjects dropped out of the study because of elevated serum concentrations of C-reactive protein. Fasting blood sera were analyzed for 25(OH)D with the high-performance liquid chromatography (HPLC) and for parathyroid hormone (PTH), immunoglobulins and complement C4 and C3 concentrations with immunoassays. The percentage of participants in each of the four 25(OH)D deficiency groups--severely deficient (<10 ng/ml), deficient (10 to 20), insufficient (21 to 29 ng/ml) and normal (>=30 ng/ml)--were statistically compared. The relationship of the major components of the humoral system and age with 25(OH)D levels was also assessed.

RESULTS

About 66% of the subjects had insufficient levels of 25(OH)D. Normal levels of 25(OH)D were found in 26.1% of the subjects of which 21% were males and 30.5% were females (total study population). Severely deficient levels of 25(OH)D were found in 7.98% of the total study population. Low levels of 25(OH)D were positively associated with IgG2 (P = 0.01) and with C4 (P = 0.02), yet were inversely related to levels of IgG1 and IgA (P < 0.05) and C3 (P = 0.01). Serum levels of total IgA, IgG, IgG2 and IgG4 peaked together with 25(OH)D during late summer.

CONCLUSIONS

Approximately two-thirds of the healthy, older Swiss population presented with Vitamin D insufficiency. The incremental shift in IgA and C3 levels might not necessarily reflect a deranged humoral immune defense; however, given the high prevalence of vitamin D deficiency, the importance of this condition in humoral immunity will be worth looking at more closely. This study supports the role of vitamin D in the competent immune system.

Pitfalls bei Laborwerten – Elektrolyte, Harnstoff und Kreatinin

Bei der Einschätzung von Parametern des Elektrolythaushalts und der Nierenfunktion kommen Überlegungen zur Pathophysiologie und zu Referenzwerten zum Tragen. Eine Hyponatriämie ist meistens durch einen Wasserüberschuss bedingt, für welchen die Flüssigkeitsrestriktion die Maßnahme der Wahl darstellt. Eine verminderte Natriumkonzentration im Harn sollte klinisch eine Beurteilung des Volumenstatus nach sich ziehen, um differentialdiagnostisch die richtigen Schlüsse zu ziehen. Die fraktionierte Natriumexkretion, vor allem aber auch die fraktionierte Harnstoffexkretion, geben bei Verdacht auf ein akutes Nierenversagen Hinweise auf eine prärenale oder renale Ursache. Störungen des Kaliumhaushalts können im Rahmen von Veränderungen in der Zufuhr, in der renalen Elimination oder in der Verteilung zwischen extra- und intrazellulärem Kompartiment auftreten. Der transtubuläre Kaliumgradient hilft in der ätiologischen Klärung einer Hyperkaliämie. Zur Einschätzung der Nierenfunktion ist die Harnstoffkonzentration im Serum ungeeignet. Jegliche Einschätzung der Nierenfunktion soll mit der Bestimmung von Serumkreatinin beginnen und von einer Schätzung der glomerulären Filtration (eGFR) nach der CKD-EPI Formel begleitet werden. Allerdings ist anzumerken, dass diese Schätzungen die tatsächliche GFR vor allem im leicht erniedrigten und normalen Bereich unterschätzen kann. Paradoxerweise überschätzt die CKD-EPI bei älteren Personen, aber auch bei hospitalisierten Patienten die tatsächliche GFR, was sich in Medikationsfehlern auswirken kann. Grund für diese Abweichungen sind non-renale Einflussfaktoren auf die Kreatininkonzentration im Serum. Eine Clearancemessung kann diesbezüglich genauere Informationen liefern.

Selected topics of the 4th International Cooperative Study Group meeting on immune thrombocytopenia revisited

The Intercontinental Cooperative immune thrombocytopenia (ITP) Study Group (ICIS) held its 4th Expert Meeting in September 2012 in Montreux, Switzerland. The program reunited researchers and clinicians from all over the globe and was organized with lectures and seminars for real-time exchange of latest information. Platelets target victims of autoimmune disease on their own, participating under physiological conditions in the immune network; these small cells are more immunologically savvy than previously thought. Currently, researchers focus their attention on regulatory T and regulatory B cells, ie, cells that might have a decisive impact on how ITP spontaneously resolves or evolves into chronic disease. Diagnostic criteria and prognosis are increasingly benefiting from molecular biological tests, and therapy has evolved with the availability of biosimilar agents and recombinant hormones or blockers of their receptors.

Genetic and phenotypic determinants of blood pressure and other cardiovascular risk factors (GAPP)

BACKGROUND

The pathogenesis of elevated blood pressure and other cardiovascular risk factors in the population and their progression over time is still incompletely understood, especially in young and healthy adults.

METHODS

The genetic and phenotypic determinants of blood pressure and other cardiovascular risk factors (GAPP) study is a population-based prospective cohort study involving a representative sample of healthy adults aged 25-41 years in the Principality of Liechtenstein. Exclusion criteria are any cardiovascular disease, diabetes, obstructive sleep apnoea syndrome, daily intake of nonsteroidal anti-inflammatory drugs and a body mass index >35 kg/m². Examinations include detailed assessment of personal, medical, lifestyle and nutritional factors, standardised assessment of weight, height and waist circumference, blood pressure measurement (clinic and 24-hour ambulatory monitoring), electrocardiography (12-lead and 24-hour Holter monitoring), bioimpedance analysis, blood, urinary and genetic sampling, spirometry and sleep pulse oximetry with nasal flow measurement. Baseline examination is still ongoing. Follow-up examinations are scheduled every 3-5 years.

RESULTS

Since June 2010, 1,333 participants have been enrolled. Mean age of the participants was 36.7 ± 4.9 years and 47.5% of all participants were male. Mean body mass index was 26.1 ± 3.1 kg/m2 in men and 23.5 ± 3.9 kg/m2 in women. The prevalence of hypertension and prediabetes was 24.7% and 32.1% in men and 6% and 23% in women respectively. Mean LDL levels were 3.34 ± 0.9 mmol/l in men and 2.75 ± 0.7 mmol/l in women. Median hsCRP was 0.9 (0.5; 1.8) mg/l with no gender differences.

CONCLUSION

GAPP affords an excellent opportunity to assess genetic and phenotypic predictors of cardiovascular risk factors and their progression over time in young and healthy adults from the general population.

Cystatin C is a strong predictor of survival in patients with cirrhosis: is a cystatin C-based MELD better?

BACKGROUND/AIMS

The model of end stage liver disease (MELD) includes serum creatinine, which is a poor surrogate marker of renal function in patients with cirrhosis. Especially in women and patients with advanced disease creatinine underestimates true renal function. Our objective was to assess whether or not the substitution of creatinine by cystatin C improves the prognostic performance of the model.

METHODS

The association between MELD parameters and cystatin C with survival was investigated using a Cox proportional hazards model. A cystatin C-based MELD score was calculated from the results and compared with creatinine-based MELD in terms of discrimination and calibration.

RESULTS

Four hundred and twenty-nine patients were included in the study; 19% died and 12% underwent liver transplantation during a median follow-up of 602 days. In multivariate Cox regression, cystatin C was an independent predictor of 90-day mortality with a hazard ratio of 8.0 (95% CI: 2.2-29.6). The median cystatin C-based MELD was 15, the median creatinine-based MELD was 12. Calibration and discrimination for 3 month and 1 year mortality was similar between the scores (AUC > 0.85 for both scores). Gender differences in cystatin C-based MELD were less pronounced than those in the creatinine-based model, because creatinine but not cystatin C was affected by gender.

CONCLUSION

Substitution of creatinine by cystatin C does not improve the predictive power of MELD.

Insights on urinary NGAL obtained in a primary care setting

BACKGROUND

A majority of patients developing acute kidney injury (AKI) receive medical care from their primary care physicians prior to the occurrence of conditions that predispose them to this complication.

METHODS

To characterize the uNGAL concentrations in primary care patients and to assess these concentrations with regard to different reference intervals, we conducted a multicenter, cross-sectional study with random selection of general practitioners (GP) from all GP offices in seven Swiss cantons. 1000 adults (566 females; mean age 57±17 years) were included.

RESULTS

The median absolute uNGAL was 21 ng/L. Elevated uNGAL (>100 ng/L) together with normal kidney test results (eGFR and albuminuria) were found in 6.5% of all patients. Females had a significantly higher uNGAL than did males. Among a multitude of different clinical and laboratory variables, only age, gender, liver function parameters, WBC and CRP were significantly associated with uNGAL levels in a multivariate analysis. When examining the proposed KDIGO classification of chronic kidney disease, the uNGAL levels at the given eGFR stages changed with increasing albuminuria stages and vice versa.

CONCLUSIONS

Age, gender, markers of inflammation and liver function, exert influences on uNGAL concentrations. A substantial proportion of patients exhibited normal kidney testing together with elevated uNGAL, potentially identifying patients with increased renal stress and at increased risk for the development of AKI.

Benefits and risks of IgA in immunoglobulin preparations

The case of Immunoglobulin A (IgA) in transfusion medicine is unsettled: on one hand IgA is an important component of adaptive immunity and its deficiency may cause disease, on the other its presence in blood products might induce, in rare instances, allergy-like symptoms if not anaphylaxis. The practice with i.v. immunoglobulins currently changes as up to 10% concentrated preparations are given at fast rates hence even trace amounts of IgA contained in these IgG preparations can cause unexpected (side-) effects. Fortunately, the spectrum of sensitive IgA assays, along with anti-IgA screening assays now permits laboratories to narrow down IgA-dependent transfusion reactions to the real cases, in which IgA was the decisive trigger of anaphylaxis, proven or not by the presence of anti-IgA of the IgG or even IgE class. Tolerance to allogenic IgA has recently been reported. The known association of HLA with IgA deficiency (IgAD) has now been completed with an association to the nonsynonymous variant in IFHI1, allowing physicians to more precisely spot recipients at risk for an IgA-dependent transfusion reaction. Our review, along with our own experience here in Switzerland, allows us to conclude that IgA is a beneficial antibody rather than an allergen to be placed at the end of the list of non-infectious transfusion complications such as TRALI, febrile non-hemolytic reactions, purpura or volume overload.

The relationship of leukocyte anisocytosis to holotranscobalamin, a marker of cobalamin deficiency

INTRODUCTION

After measurement of the mean volumes of leukocyte subpopulations as well as the distribution widths (DW) of these volumes has become available, we investigated whether such morphometric leukocyte parameters are associated with a commonly used marker of cobalamin deficiency, i.e., holotranscobalamin (HoloTC). Further, we determined reference intervals for these parameters in an elderly population.

METHODS

Consecutive subjectively healthy and volunteering individuals ≥60 years were included. Using the UniCel DxH 800 Coulter Cellular Analysis System MoMV, mean neutrophil volume (NeMV), mean lymphocyte volume (LyMV), monocyte anisocytosis (MoV-DW), neutrophil anisocytosis (NeV-DW), and lymphocyte anisocytosis (LyV-DW) were assessed together with other parameters including HoloTC.

RESULTS

A total of 150 individuals were included in the study. Reference intervals were not dependent on age and gender. MoV-DW (P = 0.002) and NeV-DW (P = 0.02) were significantly lower, and LyMV was significantly higher (P = 0.04) in participants with a HoloTC concentration <28 pm. In contrast, MCV, MoMV, NeMV, and LyV-DW were not associated with HoloTC concentrations. The area under the curve (AUC) in the receiver operating characteristic analysis for detecting a HoloTC <28 pm was 0.81 [95% confidence interval (CI) (0.73, 0.87)] for MoV-DW and 0.73 (0.66, 0.80) for NeV-DW.

CONCLUSION

In this collective of subjectively healthy elderly individuals, monocyte anisocytosis, neutrophil anisocytosis and mean lymphocyte volume were associated with decreased HoloTC.