Measuring Biological Age via Metabonomics: The Metabolic Age Score

Chronological age is one of the most important risk factors for adverse clinical outcome. Still, two individuals at the same chronological age could have different biological aging states, leading to different individual risk profiles. Capturing this individual variance could constitute an even more powerful predictor enhancing prediction in age-related morbidity. Applying a nonlinear regression technique, we constructed a metabonomic measurement for biological age, the metabolic age score, based on urine data measured via (1)H NMR spectroscopy. We validated the score in two large independent population-based samples by revealing its significant associations with chronological age and age-related clinical phenotypes as well as its independent predictive value for survival over approximately 13 years of follow-up. Furthermore, the metabolic age score was prognostic for weight loss in a sample of individuals who underwent bariatric surgery. We conclude that the metabolic age score is an informative measurement of biological age with possible applications in personalized medicine.

Endogenous Androgens and Sex Hormone-Binding Globulin in Women and Risk of Metabolic Syndrome and Type 2 Diabetes

CONTEXT AND OBJECTIVES

The association of endogenous androgens and sex hormone-binding globulin (SHBG) with metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM) mostly 23562 refers to small and selected study samples with immunoassay-based measurements. Thus, we investigated the association of hormone levels with MetS and T2DM in women from a large population-based sample.

DESIGN, SETTING, AND PARTICIPANTS

A total of 2077 women from the Study of Health in Pomerania were assessed at baseline (N = 3160, 1997-2001) and 5-year follow-up (N = 1711, 2002-2006).

MAIN OUTCOMES AND MEASURES

We investigated associations of total testosterone (T) and androstenedione measured by liquid chromatography-tandem mass spectrometry, SHBG by immunoassay, and free T and free androgen index with MetS and T2DM.

RESULTS

Baseline prevalence of MetS and T2DM was 23.1% (N = 365) and 9.5% (N = 196), with an incidence of 17.7 and 7.0 per 1.000 person-years, respectively. Cross-sectional analyses yielded inverse associations of SHBG with MetS (relative risk [RR], 0.67; 95% confidence interval [CI], 0.60-0.74) and T2DM (RR, 0.61; 95% CI, 0.50-0.74) after multivariable adjustment. In longitudinal analyses, only age-adjusted models showed an inverse association of baseline SHBG with incident MetS (RR, 0.61; 95% CI, 0.51-0.73) and T2DM (RR, 0.58; 95% CI, 0.43-0.78). Multivariable-adjusted models stratified by menopausal status revealed an inverse association between SHBG and incident MetS risk in postmenopausal women (RR, 0.65; 95% CI, 0.51-0.81).

CONCLUSIONS

This longitudinal population-based study revealed independent inverse associations of SHBG with MetS and T2DM, suggesting low SHBG as a potential risk marker for cardiometabolic morbidity, especially among postmenopausal women.

Extensive alterations of the whole-blood transcriptome are associated with body mass index: results of an mRNA profiling study involving two large population-based cohorts

Background

Obesity, defined as pathologically increased body mass index (BMI), is strongly related to an increased risk for numerous common cardiovascular and metabolic diseases. It is particularly associated with insulin resistance, hyperglycemia, and systemic oxidative stress and represents the most important risk factor for type 2 diabetes (T2D). However, the pathophysiological mechanisms underlying these associations are still not completely understood. Therefore, in order to identify potentially disease-relevant BMI-associated gene expression signatures, a transcriptome-wide association study (TWAS) on BMI was performed.

Methods

Whole-blood mRNA levels determined by array-based transcriptional profiling were correlated with BMI in two large independent population-based cohort studies (KORA F4 and SHIP-TREND) comprising a total of 1977 individuals.

Results

Extensive alterations of the whole-blood transcriptome were associated with BMI: More than 3500 transcripts exhibited significant positive or negative BMI-correlation. Three major whole-blood gene expression signatures associated with increased BMI were identified. The three signatures suggested: i) a ratio shift from mature erythrocytes towards reticulocytes, ii) decreased expression of several genes essentially involved in the transmission and amplification of the insulin signal, and iii) reduced expression of several key genes involved in the defence against reactive oxygen species (ROS).

Conclusions

Whereas the first signature confirms published results, the other two provide possible mechanistic explanations for well-known epidemiological findings under conditions of increased BMI, namely attenuated insulin signaling and increased oxidative stress. The putatively causative BMI-dependent down-regulation of the expression of numerous genes on the mRNA level represents a novel finding. BMI-associated negative transcriptional regulation of insulin signaling and oxidative stress management provide new insights into the pathogenesis of metabolic syndrome and T2D.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-015-0141-x) contains supplementary material, which is available to authorized users.

Discrepant post filter ionized calcium concentrations by common blood gas analyzers in CRRT using regional citrate anticoagulation

Introduction

Ionized calcium (iCa) concentration is often used in critical care and measured using blood gas analyzers at the point of care. Controlling and adjusting regional citrate anticoagulation (RCA) for continuous renal replacement therapy (CRRT) involves measuring the iCa concentration in two samples: systemic with physiological iCa concentrations and post filter samples with very low iCa concentrations. However, modern blood gas analyzers are optimized for physiological iCa concentrations which might make them less suitable for measuring low iCa in blood with a high concentration of citrate. We present results of iCa measurements from six different blood gas analyzers and the impact on clinical decisions based on the recommendations of the dialysis’ device manufacturer.

Method

The iCa concentrations of systemic and post filter samples were measured using six distinct, frequently used blood gas analyzers. We obtained iCa results of 74 systemic and 84 post filter samples from patients undergoing RCA for CRRT at the University Medicine of Greifswald.

Results

The systemic samples showed concordant results on all analyzers with median iCa concentrations ranging from 1.07 to 1.16 mmol/L. The medians of iCa concentrations for post filter samples ranged from 0.21 to 0.50 mmol/L. Results of >70 % of the post filter samples would lead to major differences in decisions regarding citrate flow depending on the instrument used.

Conclusion

Measurements of iCa in post filter samples may give misleading information in monitoring the RCA. Recommendations of the dialysis manufacturer need to be revised. Meanwhile, little weight should be given to post filter iCa. Reference methods for low iCa in whole blood containing citrate should be established.

Urine Metabolomics by (1)H-NMR Spectroscopy Indicates Associations between Serum 3,5-T2 Concentrations and Intermediary Metabolism in Euthyroid Humans

CONTEXT

3,5-Diiodo-L-thyronine (3,5-T2) is a thyroid hormone metabolite which exhibited versatile effects in rodent models, including the prevention of insulin resistance or hepatic steatosis typically forced by a high-fat diet. With respect to euthyroid humans, we recently observed a putative link between serum 3,5-T2 and glucose but not lipid metabolism.

OBJECTIVE

The aim of the present study was to widely screen the urine metabolome for associations with serum 3,5-T2 concentrations in healthy individuals.

STUDY DESIGN AND METHODS

Urine metabolites of 715 euthyroid participants of the population-based Study of Health in Pomerania (SHIP-TREND) were analyzed by (1)H-NMR spectroscopy. Multinomial logistic and multivariate linear regression models were used to detect associations between urine metabolites and serum 3,5-T2 concentrations.

RESULTS

Serum 3,5-T2 concentrations were positively associated with urinary levels of trigonelline, pyroglutamate, acetone and hippurate. In detail, the odds for intermediate or suppressed serum 3,5-T2 concentrations doubled owing to a 1-standard deviation (SD) decrease in urine trigonelline levels, or increased by 29-50% in relation to a 1-SD decrease in urine pyroglutamate, acetone and hippurate levels.

CONCLUSION

Our findings in humans confirmed the metabolic effects of circulating 3,5-T2 on glucose and lipid metabolism, oxidative stress and enhanced drug metabolism as postulated before based on interventional pharmacological studies in rodents. Of note, 3,5-T2 exhibited a unique urinary metabolic profile distinct from previously published results for the classical thyroid hormones.

Association between waist circumference and gray matter volume in 2344 individuals from two adult community-based samples

We analyzed the putative association between abdominal obesity (measured in waist circumference) and gray matter volume (Study of Health in Pomerania: SHIP-2, N=758) adjusted for age and gender by applying volumetric analysis and voxel-based morphometry (VBM) with VBM8 to brain magnetic resonance (MR) imaging. We sought replication in a second, independent population sample (SHIP-TREND, N=1586). In a combined analysis (SHIP-2 and SHIP-TREND) we investigated the impact of hypertension, type II diabetes and blood lipids on the association between waist circumference and gray matter. Volumetric analysis revealed a significant inverse association between waist circumference and gray matter volume. VBM in SHIP-2 indicated distinct inverse associations in the following structures for both hemispheres: frontal lobe, temporal lobes, pre- and postcentral gyrus, supplementary motor area, supramarginal gyrus, insula, cingulate gyrus, caudate nucleus, olfactory sulcus, para-/hippocampus, gyrus rectus, amygdala, globus pallidus, putamen, cerebellum, fusiform and lingual gyrus, (pre-) cuneus and thalamus. These areas were replicated in SHIP-TREND. More than 76% of the voxels with significant gray matter volume reduction in SHIP-2 were also distinct in TREND. These brain areas are involved in cognition, attention to interoceptive signals as satiety or reward and control food intake. Due to our cross-sectional design we cannot clarify the causal direction of the association. However, previous studies described an association between subjects with higher waist circumference and future cognitive decline suggesting a progressive brain alteration in obese subjects. Pathomechanisms may involve chronic inflammation, increased oxidative stress or cellular autophagy associated with obesity.

Positive Association Between Adipose Tissue and Bone Stiffness

Obesity is often considered to have a protective effect against osteoporosis. On the other hand, several recent studies suggest that adipose tissue may have detrimental effects on bone quality. We therefore aimed to investigate the associations between body mass index (BMI), waist circumference (WC), visceral adipose tissue (VAT) or abdominal subcutaneous adipose tissue (SAT), and bone stiffness. The study involved 2685 German adults aged 20-79 years, who participated in either the second follow-up of the population-based Study of Health in Pomerania (SHIP-2) or the baseline examination of the SHIP-Trend cohort. VAT and abdominal SAT were quantified by magnetic resonance imaging. Bone stiffness was assessed by quantitative ultrasound (QUS) at the heel (Achilles InSight, GE Healthcare). The individual risk for osteoporotic fractures was determined based on the QUS-derived stiffness index and classified in low, medium, and high risk. Linear regression models, adjusted for sex, age, physical activity, smoking status, risky alcohol consumption, diabetes, and height (in models with VAT or abdominal SAT as exposure), revealed positive associations between BMI, WC, VAT or abdominal SAT, and the QUS variables broadband-ultrasound attenuation or stiffness index. Moreover, BMI was positively associated with speed of sound. Our study shows that all anthropometric measures including BMI and, WC as well as abdominal fat volume are positively associated with bone stiffness in the general population. As potential predictors of bone stiffness, VAT and abdominal SAT are not superior to easily available measures like BMI or WC.

Meta-analysis of Genome-wide Association Studies for Neuroticism, and the Polygenic Association With Major Depressive Disorder

IMPORTANCE

Neuroticism is a pervasive risk factor for psychiatric conditions. It genetically overlaps with major depressive disorder (MDD) and is therefore an important phenotype for psychiatric genetics. The Genetics of Personality Consortium has created a resource for genome-wide association analyses of personality traits in more than 63,000 participants (including MDD cases).

OBJECTIVES

To identify genetic variants associated with neuroticism by performing a meta-analysis of genome-wide association results based on 1000 Genomes imputation; to evaluate whether common genetic variants as assessed by single-nucleotide polymorphisms (SNPs) explain variation in neuroticism by estimating SNP-based heritability; and to examine whether SNPs that predict neuroticism also predict MDD.

DESIGN, SETTING, AND PARTICIPANTS

Genome-wide association meta-analysis of 30 cohorts with genome-wide genotype, personality, and MDD data from the Genetics of Personality Consortium. The study included 63,661 participants from 29 discovery cohorts and 9786 participants from a replication cohort. Participants came from Europe, the United States, or Australia. Analyses were conducted between 2012 and 2014.

MAIN OUTCOMES AND MEASURES

Neuroticism scores harmonized across all 29 discovery cohorts by item response theory analysis, and clinical MDD case-control status in 2 of the cohorts.

RESULTS

A genome-wide significant SNP was found on 3p14 in MAGI1 (rs35855737; P = 9.26 × 10-9 in the discovery meta-analysis). This association was not replicated (P = .32), but the SNP was still genome-wide significant in the meta-analysis of all 30 cohorts (P = 2.38 × 10-8). Common genetic variants explain 15% of the variance in neuroticism. Polygenic scores based on the meta-analysis of neuroticism in 27 cohorts significantly predicted neuroticism (1.09 × 10-12 < P < .05) and MDD (4.02 × 10-9 < P < .05) in the 2 other cohorts.

CONCLUSIONS AND RELEVANCE

This study identifies a novel locus for neuroticism. The variant is located in a known gene that has been associated with bipolar disorder and schizophrenia in previous studies. In addition, the study shows that neuroticism is influenced by many genetic variants of small effect that are either common or tagged by common variants. These genetic variants also influence MDD. Future studies should confirm the role of the MAGI1 locus for neuroticism and further investigate the association of MAGI1 and the polygenic association to a range of other psychiatric disorders that are phenotypically correlated with neuroticism.

Adiposity measures and vitamin D concentrations in Northeast Germany and Denmark

BACKGROUND

Body mass index (BMI) and serum 25-hydroxy vitamin D3 (25OHD) concentrations are inversely related. As BMI contains only limited information regarding body fat distribution, we aimed to analyze the cross-sectional associations of abdominal visceral or subcutaneous adipose tissue, next to common adiposity measures, with the 25OHD concentration.

METHODS

Data were obtained from three cohorts of two large epidemiological studies in the northeast of Germany (Study of Health in Pomerania, SHIP-1 and SHIP-Trend), and in Denmark (Health2006). The study populations included adult men and women from the general population (N = 3072 SHIP-1, N = 803 SHIP-Trend, N = 3195 Health2006). Visceral and subcutaneous adipose tissue were quantified by magnetic resonance imagining (SHIP-Trend) or ultrasound (Health2006). Common adiposity measures, including BMI, waist circumference, waist-to-hip ratio, waist-to-height ratio, body surface area, and body fat percentage were determined by standardized methods in SHIP-1 and Health2006.

RESULTS

The average study participant was overweight (median BMI 27.4, 26.6, and 25.2 kg/m(2) in SHIP-1, SHIP-Trend, and Health2006, respectively). Visceral and subcutaneous adipose tissue as well as the common adiposity measures were inversely associated with serum 25OHD concentrations in linear regression models adjusted for age, sex, alcohol consumption, physical activity, smoking status, and month of blood sampling.

CONCLUSIONS

Next to common adiposity measures, also abdominal visceral or subcutaneous adipose tissue are inversely associated with serum 25OHD concentrations in the general adult population.

Long-term glycaemic response and tolerability of dapagliflozin versus a sulphonylurea as add-on therapy to metformin in patients with type 2 diabetes: 4-year data

AIMS

To assess the long-term efficacy and tolerability of dapagliflozin versus glipizide as add-on to metformin in patients with inadequately controlled type 2 diabetes.

METHODS

The present study was an extension of an earlier randomized, double-blind, phase III study of dapagliflozin (n = 406) vs glipizide (n = 408) to 208 weeks (4 years). Patients continued to receive their assigned medication. No statistical treatment-group comparisons were calculated.

RESULTS

At 208 weeks, dapagliflozin compared with glipizide produced sustained reductions in glycated haemoglogin (HbA1c): -0.30% [95% confidence interval (CI), -0.51 to -0.09], in total body weight: -4.38 kg (95% CI -5.31 to -3.46) and in systolic blood pressure (SBP): -3.67 mmHg (95% CI -5.92 to -1.41). The HbA1c coefficient of failure was significantly lower for dapagliflozin than for glipizide: 0.19 (95% CI 0.12-0.25) versus 0.61 (95% CI 0.49-0.72, difference -0.42; p = 0.0001). Dapagliflozin was not associated with glomerular function deterioration, while this occurred more frequently in patients in the glipizide group. Fewer patients reported hypoglycaemia in the dapagliflozin compared with the glipizide group (5.4 vs 51.5%). Genital and urinary tract infections were more common with dapagliflozin than with glipizide, but their incidence decreased with time and all events responded well to antimicrobial treatment.

CONCLUSIONS

In patients completing 4 years of treatment, dapagliflozin was well tolerated and associated with sustained glycaemic efficacy and greater reductions in body weight and SBP versus glipizide.

Associations between Serum Sex Hormone Concentrations and Whole Blood Gene Expression Profiles in the General Population

Background

Despite observational evidence from epidemiological and clinical studies associating sex hormones with various cardiometabolic risk factors or diseases, pathophysiological explanations are sparse to date. To reveal putative functional insights, we analyzed associations between sex hormone levels and whole blood gene expression profiles.

Methods

We used data of 991 individuals from the population-based Study of Health in Pomerania (SHIP-TREND) with whole blood gene expression levels determined by array-based transcriptional profiling and serum concentrations of total testosterone (TT), sex hormone-binding globulin (SHBG), free testosterone (free T), dehydroepiandrosterone sulfate (DHEAS), androstenedione (AD), estradiol (E2), and estrone (E1) measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunoassay. Associations between sex hormone concentrations and gene expression profiles were analyzed using sex-specific regression models adjusted for age, body mass index, and technical covariables.

Results

In men, positive correlations were detected between AD and DDIT4 mRNA levels, as well as between SHBG and the mRNA levels of RPIA, RIOK3, GYPB, BPGM, and RAB2B. No additional significant associations were observed.

Conclusions

Besides the associations between AD and DDIT4 expression and SHBG and the transcript levels of RPIA, RIOK3, GYPB, BPGM, and RAB2B, the present study did not indicate any association between sex hormone concentrations and whole blood gene expression profiles in men and women from the general population.

A genetic risk score for thyroid peroxidase antibodies associates with clinical thyroid disease in community-based populations

CONTEXT

Antibodies against thyroid peroxidase (TPOAbs) are detected in 90% of all patients with Hashimoto thyroiditis, the most common cause of hypothyroidism. Hypothyroidism is associated with a range of adverse outcomes. The current knowledge of its genetic underpinnings is limited.

OBJECTIVE

The purpose of this study was to identify novel genetic variants associated with TPOAb concentrations and positivity using genome-wide association data and to characterize their association with thyroid function and disease.

DESIGN, SETTING, AND PARTICIPANTS

We studied European ancestry participants of 3 independent prospective population-based studies: Atherosclerosis Risk In Communities study (n = 7524), Study of Health in Pomerania (n = 3803), and Study of Health in Pomerania-TREND (n = 887).

EXPOSURE

Single nucleotide polymorphisms (SNPs), individually and combined into a genetic risk score (GRS), were examined.

MAIN OUTCOMES

The main outcomes were TPOAb concentrations and positivity, thyroid hormone concentrations (TSH, free T4), and clinical thyroid diseases (subclinical and overt hypothyroidism and goiter).

RESULTS

Significantly associated single nucleotide polymorphisms (P < 5 · 10(-8)) mapped into 4 genomic regions not previously implicated for TPOAbs (RERE, extended HLA region) and into 5 previously described loci. A higher Genetic Risk Score (GRS) based on these 9 SNPs showed strong and graded associations with higher TPOAb, TSH, and lower free T4 concentrations (P < .001). Compared with individuals in the lowest GRS quartile, those in the highest quartile had 1.80-fold higher odds of subclinical hypothyroidism (95% confidence interval, 1.27-2.55) and 1.89-fold higher odds of overt hypothyroidism (95% confidence interval, 1.24-2.87).

CONCLUSION

The identification of 4 novel genetic loci associated with TPOAb concentrations and positivity gives further insight into the genetic underpinnings of hypothyroidism. A GRS showed strong and graded associations with markers of thyroid function and disease in independent population-based studies.

Lower bone turnover markers in metabolic syndrome and diabetes: the population-based Study of Health in Pomerania

BACKGROUND AND AIMS

Accumulating evidence demonstrates an important interaction between bone and energy metabolism. We aimed to study the associations of three bone turnover markers (BTM: osteocalcin, beta-crosslaps, procollagen type 1 N-terminal propeptide) as well as of 25-hydroxyvitamin D and parathyroid hormone with metabolic syndrome (MetS) or type 2 diabetes mellitus (T2DM) in a large population-based cohort.

METHODS AND RESULTS

This cross-sectional study comprised 2671 adult men and women participating in the first follow-up of the population-based Study of Health in Pomerania (SHIP-1). Multivariable logistic regression analyses were performed to assess sex-specific associations between the BTMs, 25-hydroxyvitamin D or parathyroid hormone and metabolic disease. All models were adjusted for age, body mass index, smoking status, physical activity, estimated glomerular filtration rate and month of blood sampling. The models for women were further adjusted for menopausal status. Higher BTM or 25-hydroxyvitamin D concentrations were associated with significantly lower odds for metabolic disease, while there was no association between parathyroid hormone and MetS or T2DM.

CONCLUSION

Our results contribute to the accumulating evidence of a cross-sectional association between high BTM or 25-hydroxyvitamin D concentrations and a lower prevalence of MetS or T2DM. Further research is necessary to evaluate the mechanisms underlying these results.

Association of circulating irisin and cardiopulmonary exercise capacity in healthy volunteers: results of the Study of Health in Pomerania

BACKGROUND

Irisin, a recently discovered myokine, is assumed to be secreted by muscle cells in response to exercise and is involved in the regulation of energy metabolism by browning white adipose tissue cells. However, due to the fact that previous studies revealed conflicting results concerning the association between irisin and exercise, the aim of the present study was to investigate the potential relationship between irisin and exercise capacity in a population-based setting.

METHODS

From the population-based Study of Health in Pomerania (SHIP-TREND) 334 men and 406 women with irisin measurements were selected and a standardised symptom limited cardiopulmonary exercise test was used. Exercise capacity was quantified by oxygen uptake at anaerobic threshold (VO2@AT), peak exercise (peakVO2) and maximum power output at peak exertion. In addition, the oxygen pulse was assessed. ANOVA and multivariable linear regression analyses were performed stratified by sex and adjusted for age, weight, height and smoking.

RESULTS

In men, we observed inverse associations between irisin serum concentration and exercise capacity assessed by peakVO2 and maximum power output. In contrast, in women a trend towards a positive relationship between irisin and peakVO2 was detected, whereas none of the other parameters showed significant associations with irisin.

CONCLUSION

Based on a large population sample, our results did not confirm the previous reported positive linkage between exercise and irisin. Thus the relationship needs further investigation in particular with respect to sex differences.

Multiethnic genome-wide association study of cerebral white matter hyperintensities on MRI

BACKGROUND

The burden of cerebral white matter hyperintensities (WMH) is associated with an increased risk of stroke, dementia, and death. WMH are highly heritable, but their genetic underpinnings are incompletely characterized. To identify novel genetic variants influencing WMH burden, we conducted a meta-analysis of multiethnic genome-wide association studies.

METHODS AND RESULTS

We included 21 079 middle-aged to elderly individuals from 29 population-based cohorts, who were free of dementia and stroke and were of European (n=17 936), African (n=1943), Hispanic (n=795), and Asian (n=405) descent. WMH burden was quantified on MRI either by a validated automated segmentation method or a validated visual grading scale. Genotype data in each study were imputed to the 1000 Genomes reference. Within each ethnic group, we investigated the relationship between each single-nucleotide polymorphism and WMH burden using a linear regression model adjusted for age, sex, intracranial volume, and principal components of ancestry. A meta-analysis was conducted for each ethnicity separately and for the combined sample. In the European descent samples, we confirmed a previously known locus on chr17q25 (P=2.7×10(-19)) and identified novel loci on chr10q24 (P=1.6×10(-9)) and chr2p21 (P=4.4×10(-8)). In the multiethnic meta-analysis, we identified 2 additional loci, on chr1q22 (P=2.0×10(-8)) and chr2p16 (P=1.5×10(-8)). The novel loci contained genes that have been implicated in Alzheimer disease (chr2p21 and chr10q24), intracerebral hemorrhage (chr1q22), neuroinflammatory diseases (chr2p21), and glioma (chr10q24 and chr2p16).

CONCLUSIONS

We identified 4 novel genetic loci that implicate inflammatory and glial proliferative pathways in the development of WMH in addition to previously proposed ischemic mechanisms.

Modulation of genetic associations with serum urate levels by body-mass-index in humans

We tested for interactions between body mass index (BMI) and common genetic variants affecting serum urate levels, genome-wide, in up to 42569 participants. Both stratified genome-wide association (GWAS) analyses, in lean, overweight and obese individuals, and regression-type analyses in a non BMI-stratified overall sample were performed. The former did not uncover any novel locus with a major main effect, but supported modulation of effects for some known and potentially new urate loci. The latter highlighted a SNP at RBFOX3 reaching genome-wide significant level (effect size 0.014, 95% CI 0.008-0.02, Pinter= 2.6 x 10-8). Two top loci in interaction term analyses, RBFOX3 and ERO1LB-EDARADD, also displayed suggestive differences in main effect size between the lean and obese strata. All top ranking loci for urate effect differences between BMI categories were novel and most had small magnitude but opposite direction effects between strata. They include the locus RBMS1-TANK (men, Pdifflean-overweight= 4.7 x 10-8), a region that has been associated with several obesity related traits, and TSPYL5 (men, Pdifflean-overweight= 9.1 x 10-8), regulating adipocytes-produced estradiol. The top-ranking known urate loci was ABCG2, the strongest known gout risk locus, with an effect halved in obese compared to lean men (Pdifflean-obese= 2 x 10-4). Finally, pathway analysis suggested a role for N-glycan biosynthesis as a prominent urate-associated pathway in the lean stratum. These results illustrate a potentially powerful way to monitor changes occurring in obesogenic environment.

Shift of the TSH reference range with improved iodine supply in Northeast Germany

OBJECTIVE

Germany was iodine deficient until the mid-1990s when a nationwide iodine fortification program became effective. It is expected that after a longer period of sufficient iodine supply, median TSH values in the general population will shift to the right. Hence, the previous TSH reference range does not reflect the current TSH distribution in the general population of Germany. Thus, we aimed to establish a new reference range for serum TSH levels.

DESIGN AND METHODS

We used data from the Study of Health in Pomerania TREND, a population-based study including 4420 individuals. The reference population consisted of 1596 individuals without diagnosed thyroid diseases or thyroid-related findings in ultrasound and serum analysis. Serum TSH levels were measured by an immunochemiluminescent procedure on a Siemens Dimension Vista.

RESULTS

The overall reference range for TSH was 0.49 mIU/l (95% CI=0.44; 0.53)-3.29 mIU/l (95% CI=3.08; 3.50). The lower reference limit differed significantly by sex, whereas the upper reference limit showed no significant difference between males and females. Age was significantly associated with the 2.5th TSH percentile in males but not in females, whereas age was significantly associated in males and females for the 97.5th TSH percentile.

CONCLUSIONS

We demonstrate a shift toward the right of the TSH reference range in comparison with data from the same study region 10 years earlier, which is likely due to the improved iodine supply of the study region. Our study indicates that TSH reference limits are dependent on past and current iodine supply of populations.

Higher serum concentrations of N-terminal pro-B-type natriuretic peptide associate with prevalent hypertension whereas lower associate with incident hypertension

Background

The role of the natriuretic peptides (NPs) in hypertension is complex. Thus, a higher blood NP concentration is a robust marker of pressure-induced cardiac damage in patients with hypertension, whereas genetically elevated NP concentrations are associated with a reduced risk of hypertension and overweight individuals presumably at high risk of hypertension have lower NP concentrations.

Objective

To investigate the associations between serum N-terminal pro-B-type natriuretic peptide (NT-proBNP), used as a surrogate marker for active BNP, and prevalent as well as 5-year incident hypertension in a Danish general population sample.

Methods

Cross-sectional and prospective population-based study.

Results

At baseline, among 5,307 participants (51.3% women, mean age 46.0±7.9 years) with a complete set of data, we recorded 1,979 cases with prevalent hypertension (PHT). Among 2,389 normotensive participants at baseline with a complete set of data, we recorded 324 cases with incident hypertension (IHT) on follow-up 5 years later. In models adjusted for age, sex, lifestyle, social, dietary, anthropometric, pulmonic, lipid, metabolic and renal risk factors, as well as heart rate and baseline blood pressure (only incident model), one standard deviation increase in baseline log-transformed NT-proBNP concentrations was on one side associated with a 21% higher risk of PHT (odds ratio [OR]: 1.21 [95% confidence interval (CI): 1.13-1.30], P<0.001), and on the other side with a 14% lower risk of IHT (OR: 0.86 [95%CI:0.76-0.98], P = 0.020).

Conclusions

Higher serum concentrations of NT-proBNP associate with PHT whereas lower concentrations associate with IHT. This suggests that a lower amount of circulating BNP, resulting in diminished vasodilation and natriuresis, could be involved in the pathogenesis of hypertension in its early stages.

Translating pharmacological findings from hypothyroid rodents to euthyroid humans: is there a functional role of endogenous 3,5-T2?

BACKGROUND

During the last two decades, it has become obvious that 3,5-diiodothyronine (3,5-T2), a well-known endogenous metabolite of the thyroid hormones thyroxine (T4) or triiodothyronine (T3), not only represents a simple degradation intermediate of the former but also exhibits specific metabolic activities. Administration of 3,5-T2 to hypothyroid rodents rapidly stimulated their basal metabolic rate, prevented high-fat diet-induced obesity as well as steatosis, and increased oxidation of long-chain fatty acids.

OBJECTIVE

The aim of the present study was to analyze associations between circulating 3,5-T2 in human serum and different epidemiological parameters, including age, sex, or smoking, as well as measures of anthropometry, glucose, and lipid metabolism.

METHODS

3,5-T2 concentrations were measured by a recently developed immunoassay in sera of 761 euthyroid participants of the population-based Study of Health in Pomerania. Subsequently, analysis of variance and multivariate linear regression analysis were performed.

RESULTS

Serum 3,5-T2 concentrations exhibited a right-skewed distribution, resulting in a median serum concentration of 0.24 nM (1st quartile: 0.20 nM; 3rd quartile: 0.37 nM). Significant associations between 3,5-T2 and serum fasting glucose, thyrotropin (TSH), as well as leptin concentrations were detected (p<0.05). Interestingly, the association to leptin concentrations seemed to be mediated by TSH. Age, sex, smoking, and blood lipid profile parameters did not show significant associations with circulating 3,5-T2.

CONCLUSION

Our findings from a healthy euthyroid population may point toward a physiological link between circulating 3,5-T2 and glucose metabolism.