Evaluation of plasma N-terminal pro-B-type natriuretic peptide levels in healthy North American Salukis with normal echocardiographic measurements.

Measurement of N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels has been shown to have clinical significance for diagnosis and management of heart disease in dogs. Evaluation of current reference limits for specific breeds is necessary to ensure the test can accurately distinguish between healthy and diseased animals. The objective of this study is to evaluate the adequacy of currently established NT-proBNP reference limits for clinical use in healthy Salukis. Cardiac health of 33 clinically healthy Salukis was evaluated via echocardiography using available breed standards. Plasma concentrations of NT-proBNP were measured using a commercially available assay. A one-sided 97.5% upper reference limit for the NT-proBNP concentrations was calculated using non-parametric percentile method. The 97.5% upper reference limit was 769 pmol/L (90% CI, 547-1214 pmol/L) for the study dogs. This upper reference limit was within the currently established non-breed specific NT-proBNP upper reference limit of 900 pmol/L. No relationship between sex, age, or body weight on plasma levels of NT-proBNP was noted. Results of this study supports the use of currently available non-breed specific NT-proBNP cut-off values for clinical evaluation of healthy Salukis.

Evolution of the slopes of ST2 and galectin-3 during marathon and ultratrail running compared to a control group.

Background Previous studies have suggested that exercising may induce cardiac damage. Galectin-3 (Gal-3) and soluble suppression of tumorigenicity 2 (ST2) are very interesting biomarkers for heart failure and myocardial fibrosis. We aimed to compare the kinetics of emerging fibrosis cardiac biomarkers as Gal-3 and ST-2 in endurance runners, and recreational runners before and after a running event represented by a marathon and an ultratrail event. Methods Blood samples were taken from 19 healthy non-elite marathon runners (42 km), 27 ultratour runners (67 km), and 14 recreational runners who represented the control group (10 km) just before the run (T0), just after (T1) and 3 h after (T2), in order to analyze Gal-3, ST2, hsTnT, NT-proBNP, CKMB and hsCRP. We compared the percentage of evolution and the slopes obtained from T0 to T1 (pT0T1) and from T1 to T2 (pT1T2), between the different groups of runners participating in three different races. Results Plasma cardiac biomarker concentrations increased significantly from baseline to immediately post-exercise and most of the time decreased over the subsequent 3-h period. For pT0T1 and pT1T2, the markers Gal-3 and ST2 showed a significant difference between types of run (p < 0.05 and p < 0.0001, respectively). During the recovery time, Gal-3 returned to the baseline values but not ST2 which continued to increase. Conclusions Gal-3 and ST2 are considered as a reflection of cardiac fibrosis and remodeling. The evolution of both was different, particularly after the recovery time. ST2 values exceeding cutoff values at any time.

Evaluation of analytical performances using standardized analytical protocols and comparison of clinical results of the new ADVIA BNP and NT-proBNP immunoassays for the Centaur XPT platform.

Background The study aim was to evaluate and compare analytical performances and clinical results of ADVIA BNP and PBNP methods using the Centaur XPT platform with those of Access BNP, using the DxI platform and the ECLIA NT-proBNP method, using the Cobas e411 platform, respectively. Methods Limits of blank (LoB), detection (LoD) and quantitation (LoQ) at 20% CV and 10% CV were evaluated according to international standardized protocols. The analytical parameters were assessed throughout a 90-working-day period using three curve calibrations. Results LoB, LoD and LoQ at 20% CV and 10% values of the ADVIA BNP method were 1.0 ng/L, 2.0 ng/L, 3.7 ng/L and 10.2 ng/L, respectively; while those of the ADVIA PBNP method were 1.3 ng/L, 3.0 ng/L, 9.7 ng/L and 22.3 ng/L, respectively. The ADVIA BNP and PBNP methods were able to measure the clinical decision values suggested by international guidelines for diagnosis of heart failure (HF) with an imprecision ≤6%. BNP concentrations measured with the ADVIA and Access methods showed a close linear regression (R=0.9923, n=200); a close linear regression was also found between NT-proBNP concentrations measured with the ADVIA and ECLIA methods (R=0.9954, n=202). However, the ADVIA method measured significantly lower BNP values than the Access method (on average -20.9%), while ADVIA PBNP method measured significantly higher NT-proBNP concentrations than the ECLIA method (on average +17.8%). Conclusions Analytical performances of the BNP and PBNP ADVIA methods are well in accordance with the quality specifications required by international guidelines for diagnosis and follow-up of patients with HF.

Age and Sex Distributions of Age-Related Biomarker Values in Healthy Older Adults from the Long Life Family Study.

OBJECTIVES: To determine reference values for laboratory tests in individuals aged 85 and older. DESIGN: Cross-sectional cohort study. SETTING: International. PARTICIPANTS: Long Life Family Study (LLFS) participants (N~5,000, age: range 25-110, median 67, 45% male). MEASUREMENTS: Serum biomarkers were selected based on association with aging-related diseases and included complete blood count, lipids (triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, total cholesterol), 25-hydroxyvitamin D2 and D3, vitamin D epi-isomer, diabetes mellitus-related biomarkers (adiponectin, insulin, insulin-like growth factor 1, glucose, glycosylated hemoglobin, soluble receptor for advanced glycation endproduct), kidney disease-related biomarkers (albumin, creatinine, cystatin), endocrine biomarkers (dehydroepiandrosterone, sex-hormone binding globulin, testosterone), markers of inflammation (interleukin 6, high-sensitivity C-reactive protein, N-terminal pro b-type natriuretic peptide), ferritin, and transferrin. RESULTS: Of 38 measured biomarkers, 34 were significantly correlated with age. Summary statistics were generated for all biomarkers according to sex and 5-year age increments from 50 and up after excluding participants with diseases and treatments that were associated with biomarkers. A biomarker data set was also generated that will be useful for other investigators seeking to compare biomarker levels between studies. CONCLUSION: Levels of several biomarkers change with older age in healthy individuals. The descriptive statistics identified herein will be useful in future studies and, if replicated in additional studies, might also become useful in clinical practice. The availability of the reference data set will facilitate appropriate calibration of biomarkers measured in different laboratories.

Distribution of circulating cardiac biomarkers in healthy children: from birth through adulthood.

AIM: While circulating biomarkers are critical tools for cardiovascular adult care, their relevance in childhood is unknown. METHODS: We evaluated the behavior of plasma concentrations of clinically relevant cardiac biomarkers (NT-proBNP, hs-cTnI, sST2, Galectin-3) in 106 healthy children. RESULTS: Subjects were divided into age subgroups: 24 newborns (0-30 days), 26 infants (1-12 months), 30 children (1-12 years) and 26 adolescents (13-18 years). Healthy adults were used as control. NT-proBNP (newborns: 504.3 [211.07-942.7] ng/L, median [25-75 percentiles]; infants: 200.64 [76.88-306.73]; children: 97.27 [49.24-271.80]; adolescents: 24.35 [13.14-58.83]; p < 0.001) and hs-cTnI (newborns: 9.3 [3.3-93.8] ng/L; infants: 13.8 [4.82-72.52]; children: 11.45 [4.0-48.10]; adolescents: 2.6[2.07-3.90]; p < 0.001) were highest in the first month of life, showing a decline in the next years. sST2 and Galectin-3 showed no differences. CONCLUSION: Changes in hs-cTnI and NT-proBNP suggest the design of age- and sex-based reference intervals that will have to be explored in a larger population.

Prognostic role of BNP in children undergoing surgery for congenital heart disease: analysis of prediction models incorporating standard risk factors.

BACKGROUND: The routine use of brain natriuretic peptide (BNP) in pediatric cardiac surgery remains controversial. Our aim was to test whether BNP adds information to predict risk in pediatric cardiac surgery. METHODS: In all, 587 children undergoing cardiac surgery (median age 6.3 months; 1.2-35.9 months) were prospectively enrolled at a single institution. BNP was measured pre-operatively, on every post-operative day in the intensive care unit, and before discharge. The primary outcome was major complications and length ventilator stay >15 days. A first risk prediction model was fitted using Cox proportional hazards model with age, body surface area and Aristotle score as continuous predictors. A second model was built adding cardiopulmonary bypass time and arterial lactate at the end of operation to the first model. Then, peak post-operative log-BNP was added to both models. Analysis to test discrimination, calibration, and reclassification were performed. RESULTS: BNP increased after surgery (p<0.001), peaking at a mean of 63.7 h (median 36 h, interquartile range 12-84 h) post-operatively and decreased thereafter. The hazard ratios (HR) for peak-BNP were highly significant (first model HR=1.40, p=0.006, second model HR=1.44, p=0.008), and the log-likelihood improved with the addition of BNP at 12 h (p=0.006; p=0.009). The adjunction of peak-BNP significantly improved the area under the ROC curve (first model p<0.001; second model p<0.001). The adjunction of peak-BNP also resulted in a net gain in reclassification proportion (first model NRI=0.089, p<0.001; second model NRI=0.139, p=0.003). CONCLUSIONS: Our data indicates that BNP may improve the risk prediction in pediatric cardiac surgery, supporting its routine use in this setting.

[BNP and NT-proBNP: reference values and cutoff limits]. / BNP et NT-proBNP: valeurs de référence et seuils décisionnels.

Natriuretic peptides, particularly BNP and NT-proBNP, are increasingly used as screening test in patients with symptoms suggestive of heart failure (HF). Due to their high negative predictive values, natriuretic peptide determinations allow to exclude chronic HF with great certainty and to identify patients for whom echography is not necessary. These biomarkers are also useful for diagnostic purposes, high plasma levels being related to an increased risk of cardiovascular hospitalisation and death. Risk stratification in patients with HF symptoms is based on "low" and "high" cut-off limits, for which different values have been proposed. The aim of this paper is to discuss the delineation of the decision limits and the intermediate grey zone in comparison to NT-proBNP reference values obtained in a representative group of subjects living in the Liège area (Belgium). Data were analysed in relation to age and gender, two of the main parameters influencing the natriuretic peptide plasma levels.

Reference intervals for brain natriuretic peptide in healthy newborns and infants measured with an automated immunoassay platform.

BACKGROUND: In order to assess the reference intervals for B-type natriuretic hormone (BNP) in the first days of life, we measured peptide concentrations using the fully automated Access platform. METHODS: Plasma BNP was measured in 188 apparently healthy newborns and infants throughout the first month of extra-uterine life, as well as in 245 healthy infants ranging from 1 month to 12 years of age. RESULTS: BNP showed the highest concentrations in the first 2 days of life, with a progressive decline afterwards. Moreover, BNP values in the first week of life were significantly higher (p<0.0001) than values observed in the next periods. As a result, a significant negative correlation was found between BNP and age values when considering all 433 samples (rho=-0.816, p<0.0001 by the Spearman rank correlation test). There was no significant difference between BNP values found in males and females. CONCLUSIONS: According to this data, our study indicates that at least two reference intervals should be used for newborns and infants. The first, with higher BNP values for neonates in the first week of extra-uterine life, and the other, with lower BNP values for infants aged 2 weeks to 12 years.

A sandwich ELISA for assessment of pharmacokinetics of HSA-(BNP)2 fusion protein in mouse plasma.

Brain natriuretic peptide (BNP) is a circulating hormone of cardiac origin that plays an important role in the regulation of intravascular blood volume and vascular tone. HSA-(BNP)(2), derived from the joining of human BNP to the C-terminus of human serum albumin (HSA), has been developed to prolong the BNP pharmacodynamic action. For the analysis of pharmacokinetics of the new drug, a novel sandwich enzyme-linked immunosorbent assay (ELISA) was established and validated to quantify HSA-(BNP)(2) fusion protein in mouse plasma. The ELISA method was calibrated with 1:10 and 1:100 dilutions of blank mouse plasma spiked with HSA-(BNP)(2) standard and validated with respect to parallelism, precision (intra- and inter-assay variation), accuracy (recovery), specificity and stability. The practical working range was estimated to be 31.2-2000ng/ml with the limit of detection was 7.8ng/ml. Recoveries ranged from 80.5 to 108.4%, while the intra- and inter-assay precisions were <2.73% and <4.32%, respectively. The terminal half-life of HSA-(BNP)(2) was 2.14h, which had extended more than 40 times compared to 3.1min half-life of BNP monomer in mouse.

Clinical relevance of biological variation: the lesson of brain natriuretic peptide (BNP) and NT-proBNP assay.

The clinical relevance of brain natriuretic peptide (BNP) and N-terminal (NT)-proBNP assays as a diagnostic tool and prognostic marker in patients with cardiovascular diseases has recently been confirmed. However, several studies demonstrated variation of intra-individual BNP concentrations of >30% (ranging from 30% to 50%) with reference change values at the 95% confidence interval (i.e., the estimated critical difference) ranging from 99% to 130% in healthy subjects and heart failure patients. According to this estimated confidence interval, only a great variation in plasma BNP levels should be considered significant in an individual patient (for example, a decrease of >50% or an increase of more than two-fold). Many recent clinical studies have demonstrated that BNP variations below this estimated critical difference could also have clinical relevance. Like the concentration of other neuro-hormones, levels of plasma BNP fluctuate widely and rapidly along with heart rhythm and blood pressure variations in response to physiological stimuli. However, biological variation of BNP should not be interpreted strictly as random fluctuation around a homeostatic set point, as assumed by the common model used in all studies on biological variation of BNP reported in the literature. These results cannot be directly transferred to clinical practice. While awaiting more accurate studies, we suggest that variations of plasma BNP three-fold greater than the analytical imprecision should be considered as potentially relevant from a physiological and clinical point of view.

N-terminal-pro-B-type natriuretic peptide (NT-proBNP): reference range for Chinese apparently healthy people and clinical performance in Chinese elderly patients with heart failure.

BACKGROUND: N-terminal-pro-B-type natriuretic peptide (NT-proBNP) has been found to be a useful marker for the diagnosis of heart failure (HF) and left ventricular systolic dysfunction. We established a reference range for Chinese apparently healthy people based on age and gender and evaluated the clinical performance of NT-proBNP in the diagnosis of asymptomatic and symptomatic HF. METHODS: A group of 442 apparently healthy subjects were enrolled for reference range study. For the clinical performance study, serum NT-proBNP and clinical data were analyzed in 111 elderly patients with HF and 60 normal elderly controls. Serum NT-proBNP was measured by the Roche Elecsys 2010 immunoassay analyzer. RESULTS: NT-proBNP reference range in Chinese people based on age and gender was <83.72 ng/l for men and <131.6 ng/l for women aged 60 years, which were lower than those for western countries. NT-proBNP had a close correlation with New York Heart Association (NYHA) classification (r=0.818) and LVEF (r=-0.636). The ROC curve analysis revealed an AUC of 0.921 for the diagnosis of HF, 0.840 for asymptomatic HF (NYHA I) and 0.951 for symptomatic HF (NYHA II-IV). The optimal cutoff values for detecting HF, asymptomatic HF and symptomatic HF were 102.2, 102.2, and 204.8 ng/l, respectively. NT-proBNP had high positive predictive value (PPV) for the diagnosis of HF (96.8%), asymptomatic HF (90.3%) and symptomatic HF (90.9%), but low negative predictive value (NPV) for diagnosing HF and asymptomatic HF (74.0% and 78.1%, respectively) except symptomatic HF (93.3%). CONCLUSIONS: Chinese people have lower reference range of serum NT-proBNP. NT-proBNP assay has a good clinical performance for the diagnosis of symptomatic HF but is not suitable as a screening test for HF.

Reference interval determination for N-terminal-B-type natriuretic peptide (NT-proBNP): a study in blood donors.

We assessed reference values in a group of apparently healthy blood donors. A total of 1980 blood donors was recruited and tested for the presence of NT-proBNP using a newly developed electrochemiluminescence immunoassay (ECLIA) method. NT-proBNP clustered in all blood donors below the age of 50 years and an upper limit of normal (ULN) was found to be 84 pg/ml for males and 146 pg/ml for females. Mean NT-proBNP values increased with increasing age which was due to an increasing number of individuals exceeding the ULN. Age- and gender-appropriate NT-proBNP levels decreased with increasing hemoglobin levels. Hemoglobin but not creatinine levels influenced the NT-proBNP concentration in this cohort. The upper limit of normal can be used in clinical studies to further assess groups of diseased individuals to define clinical cutoffs.