Additional file 1: of Physical activity and metabolic health in chronic kidney disease: a cross-sectional study

Supplementary Material Physical Activity and Metabolic Health in CKD. Figure S1 and Tables S1–5). (DOCX 63 kb

Effects of calcium, magnesium, and potassium concentrations on ventricular repolarization in unselected individuals.

Background: Subclinical changes on the electrocardiogram are risk factors for cardiovascular mortality. Recognition and knowledge of electrolyte associations in cardiac electrophysiology are based on only in vitro models and observations in patients with severe medical conditions.Objectives: This study sought to investigate associations between serum electrolyte concentrations and changes in cardiac electrophysiology in the general population.Methods: Summary results collected from 153,014 individuals (54.4% women; mean age 55.1 ± 12.1 years) from 33 studies (of 5 ancestries) were meta-analyzed. Linear regression analyses examining associations between electrolyte concentrations (mmol/l of calcium, potassium, sodium, and magnesium), and electrocardiographic intervals (RR, QT, QRS, JT, and PR intervals) were performed. The study adjusted for potential confounders and also stratified by ancestry, sex, and use of antihypertensive drugs.Results: Lower calcium was associated with longer QT intervals (-11.5 ms; 99.75% confidence interval [CI]: -13.7 to -9.3) and JT duration, with sex-specific effects. In contrast, higher magnesium was associated with longer QT intervals (7.2 ms; 99.75% CI: 1.3 to 13.1) and JT. Lower potassium was associated with longer QT intervals (-2.8 ms; 99.75% CI: -3.5 to -2.0), JT, QRS, and PR durations, but all potassium associations were driven by use of antihypertensive drugs. No physiologically relevant associations were observed for sodium or RR intervals.Conclusions: The study identified physiologically relevant associations between electrolytes and electrocardiographic intervals in a large-scale analysis combining cohorts from different settings. The results provide insights for further cardiac electrophysiology research and could potentially influence clinical practice, especially the association between calcium and QT duration, by which calcium levels at the bottom 2% of the population distribution led to clinically relevant QT prolongation by >5 ms.</p

Genome-wide association for serum calcium in discovery analysis in Europeans.

<p>Manhattan plot showing −log₁₀(P values) for all SNPs in the discovery GWAS for uncorrected serum calcium in Europeans (N = 39,400), ordered by chromosomal position. The plot is truncated at −log10 P values of 10 (truncated −log₁₀P values for GCKR and CASR). The values correspond to the association of uncorrected serum calcium, including age and sex as covariates in the model as well as study-specific covariates if needed. The gene closest to the SNP with the lowest P value is listed at each locus. Six loci reached genome-wide significance (<i>P</i><5E-08) at discovery analysis (<i>GCKR</i>, <i>DGKD</i>, <i>CASR</i>, <i>VKORC1L1</i> (in grey on chromosome 7), <i>CARS</i> and <i>CYP24A1</i>. The seven loci that reached genome-wide significance at the combined analysis following replication are highlighted in red (<i>GCKR</i>, <i>DGKD</i>, CASR, <i>GATA3</i>, <i>CARS</i>, <i>DGKH</i>-KIAA0564 and <i>CYP24A1</i>).</p

Relative mRNA expression of identified genes from mice fed a low (0.17%) and high (1.69%) calcium diet compared to mice fed a normal calcium diet (0.82%).

<p>Data are means± SEM of values obtained from 5 mice for each diet group. Expression levels were normalized to actin. Statistical significance of the difference between diets was calculated using unpaired t-test. *: <i>P</i>≤0.05 (low compared to high); §: <i>P</i>≤0.05 (low compared to normal); # <i>P</i>≤0.05 (high compared to normal).</p

Relative mRNA expression of replicated genes in three calcium-transporting tissues (kidney, duodenum, tibia).

<p>The expression (based on delta CT [cycle threshold] normalized to actin) of the selected genes is compared to the expression of the <i>CASR</i> gene in the duodenum, thereby providing a relative expression. Cut-off was set at delta CT≤15. Data are means ± standard error of the mean (SEM) of values obtained from 5 mice fed a normal diet. <i>GCKR</i> was not expressed.</p

Relative mRNA expression of identified genes in kidney tubule segments.

<p>The renal tubular segments analyzed were the proximal tubule (PROX), the thick ascending limb of the loop of Henle (TAL), the distal convoluted tubule and connecting tubule (DCT-CNT), and the cortical collecting duct (CCD). The expression (based on the delta CT [cycle threshold]) of the selected genes is compared to the expression of the <i>CASR</i> gene in the PROX, thereby providing a relative expression. Data are means of values obtained from 3 mice fed a normal diet. <i>GCKR</i> was not expressed.</p

Genome-wide significant and replicated loci for serum calcium in Europeans.

<p>P values are corrected for inflation using genomic control. Replication criteria: overall genome-wide significance (<i>P</i><5E-8) and one-sided replication <i>P</i><0.05. I² was zero for rs1801725, rs1550532, rs10491003, rs7336933 and rs1570669 (I²<i>P</i>>0.20). For rs780094 and rs7481584, I² were 0.79 and 0.43 with I²<i>P</i> 0.03 and 0.19, respectively. For these latter SNPs, sample size weighted meta-analysis P values were 2.93E-10 and 2.03E-10, respectively.</p><p>Chr, chromosome. Effect A1 = beta regression coefficient for allele A1; SE, standard error.</p>*<p>one-sided P values.</p

Look-ups of serum calcium loci with related phenotypes: bone mineral density in the GEFOS dataset [6] and endocrine phenotypes from the SHIP, SHIP Trend and SUNLIGHT [7] datasets.

<p>NA, not available. P values<0.05 were considered as statistically significant. A1, effect allele. β, regression coefficient for allele A1, SE, standard error. P, two-sided P value. Zscore, z score.</p