Urinary tetrahydroaldosterone is associated with circulating FGF23 in kidney stone formers.

The spectrum of diseases with overactive renin-angiotensin-aldosterone system (RAS) or elevated circulating FGF23 overlaps, but the relationship between aldosterone and FGF23 remains unclarified. Here, we report that systemic RAS activation sensitively assessed by urinary tetrahydroaldosterone excretion is associated with circulating C-terminal FGF23. We performed a retrospective analysis in the Bern Kidney Stone Registry, a single-center observational cohort of kidney stone formers. Urinary excretion of the main aldosterone metabolite tetrahydroaldosterone was measured by gas chromatography-mass spectrometry. Plasma FGF23 concentrations were measured using a C-terminal assay. Regression models were calculated to assess the association of plasma FGF23 with 24 h urinary tetrahydroaldosterone excretion. We included 625 participants in the analysis. Mean age was 47 ± 14 years and 71% were male. Mean estimated GFR was 94 ml/min per 1.73 m2. In unadjusted analyses, we found a positive association between plasma FGF23 and 24 h urinary tetrahydroaldosterone excretion (β: 0.0027; p = 4.2 × 10-7). In multivariable regression models adjusting for age, sex, body mass index and GFR, this association remained robust (β: 0.0022; p = 2.1 × 10-5). Mineralotropic hormones, 24 h urinary sodium and potassium excretion as surrogates for sodium and potassium intake or antihypertensive drugs did not affect this association. Our data reveal a robust association of RAS activity with circulating FGF23 levels in kidney stone formers. These findings are in line with previous studies in rodents and suggest a physiological link between RAS system activation and FGF23 secretion

Impact of potassium citrate on urinary risk profile, glucose and lipid metabolism of kidney stone formers in Switzerland

Background Hypocitraturia and hypercalciuria are the most prevalent risk factors in kidney stone formers (KSFs). Citrate supplementation has been introduced for metaphylaxis in KSFs. However, beyond its effects on urinary parameters and stone recurrence, only a few studies have investigated the impact of citrate on other metabolic pathways such as glucose or lipid metabolism. Methods We performed an observational study using data from the Swiss Kidney Stone Cohort. Patients were subdivided into two groups based on treatment with potassium citrate or not. The outcomes were changes of urinary risk parameters, haemoglobin A1c (HbA1c), fasting glucose, cholesterol and body mass index (BMI). Results Hypocitraturia was present in 19.3% of 428 KSFs and potassium citrate was administered to 43 patients (10.0%) at a mean dosage of 3819 ± 1796 mg/day (corresponding to 12.5 ± 5.9 mmol/ day). Treatment with potassium citrate was associated with a significantly higher mean change in urinary citrate (P = 0.010) and urinary magnesium (P = 0.020) compared with no potassium citrate treatment. Exogenous citrate administration had no effect on cholesterol, fasting glucose, HbA1c and BMI. Multiple linear regression analysis demonstrated no significant association of 1,25-dihydroxyvitamin D3 [1,25(OH)2 D3] levels with urinary citrate excretion. Conclusion Potassium citrate supplementation in KSFs in Switzerland resulted in a beneficial change of the urinary risk profile by particularly increasing anti-lithogenic factors. Fasting glucose, HbA1c, cholesterol levels and BMI were unaffected by potassium citrate therapy after 3 months, suggesting that potassium citrate is safe and not associated with unfavourable metabolic side effects. Lastly, 1,25(OH)2 D3 levels were not associated with urinary citrate excretion

The Swiss Kidney Stone Cohort (SKSC), a longitudinal, multi-centric, observational cohort to study course and causes of kidney stone disease in Switzerland

Kidney stone disease has a high prevalence worldwide of approximately 10 % of the population and is characterized by a high recurrence rate Kidney stone disease results from a combination of genetic, environmental, and life-style risk factors, and the dissection of these factors is complex. The Swiss Kidney Stone Cohort (SKSC) is an investigator-initiated prospective, multi-centric longitudinal, observational study in patients with kidney stones followed with regular visits over a period of 3 years after inclusion. Ongoing follow-ups by biannual telephone interviews will provide long-term outcome data up to 10 years. SKSC comprises 782 adult patients (age > 18 yrs) with either recurrent stones or a single stone event with at least one risk factor for recurrence. In addition, a control cohort of 207 individuals without kidney stone history and absence of kidney stones on a low-dose CT-scan at enrolment has also been recruited. SKSC includes extensive collections of clinical data, biochemical data in blood and 24 hr urine samples, and genetic data. Biosamples are stored at a dedicated biobank. Information on diet and dietary habits were collected through food frequency questionnaires and standardized recall interviews by trained dieticians with the Globodiet software. SKSC provides an unique opportunity and resource to further study cause and course of kidney disease in a large population with data and samples collected of a homogenous collective of patients throughout the whole Swiss population

Differences in the food consumption between kidney stone formers and non-formers in the Swiss Kidney Stone Cohort.

OBJECTIVE Diet has a major influence on the formation and management of kidney stones. However, kidney stone formers' diet is difficult to capture in a large population. Our objective was to describe the dietary intake of kidney stone formers in Switzerland and to compare it to non-stone formers. METHODS We used data from the Swiss Kidney Stone Cohort (n=261), a multicentric cohort of recurrent or incident kidney stone formers with additional risk factors, and a control group of CT-scan proven non-stone formers (n=197). Dieticians conducted two consecutive 24-h dietary recalls, using structured interviews and validated software (GloboDiet). We took the mean consumption per participant of the two 24-h dietary recalls to describe the dietary intake and used two-part models to compare the two groups. RESULTS The dietary intake was overall similar between stone and non-stone formers. However, we identified that kidney stone formers had a higher probability of consuming cakes and biscuits (odds ratio, OR[95% CI] =1.56[1.03; 2.37]) and soft drinks (OR=1.66[1.08; 2.55]). Kidney stone formers had a lower probability of consuming nuts and seeds (OR =0.53[0.35; 0.82]), fresh cheese (OR=0.54[0.30; 0.96]), teas (OR=0.50[0.3; 0.84]), and alcoholic beverages (OR=0.35[0.23; 0.54]), especially wine (OR=0.42[0.27; 0.65]). Furthermore, among consumers, stone formers reported smaller quantities of vegetables (β coeff[95% CI]= - 0.23[- 0.41; - 0.06]), coffee (β coeff= - 0.21[- 0.37; - 0.05]), teas (β coeff= - 0.52[- 0.92; - 0.11]) and alcoholic beverages (β coeff= - 0.34[- 0.63; - 0.06]). CONCLUSION Stone formers reported lower intakes of vegetables, tea, coffee, and alcoholic beverages, more specifically wine, but reported drinking more frequently soft drinks than non-stone formers. For the other food groups, stone formers and non-formers reported similar dietary intakes. Further research is needed to better understand the links between diet and kidney stone formation and develop dietary recommendations adapted to the local settings and cultural habits

Urinary steroid profiling in women hints at a diagnostic signature of the polycystic ovary syndrome: A pilot study considering neglected steroid metabolites.

Although the polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women with vast metabolic consequences, its etiology remains unknown and its diagnosis is still made by exclusion. This study aimed at characterizing a large number of urinary steroid hormone metabolites and enzyme activities in women with and without PCOS in order to test their value for diagnosing PCOS. Comparative steroid profiling of 24h urine collections using an established in-house gas-chromatography mass spectrometry method. Data were collected mostly prospectively. Patients were recruited in university hospitals in Switzerland. Participants were 41 women diagnosed with PCOS according to the current criteria of the Androgen Excess and PCOS Society Task Force and 66 healthy controls. Steroid profiles of women with PCOS were compared to healthy controls for absolute metabolite excretion and for substrate to product conversion ratios. The AUC for over 1.5 million combinations of metabolites was calculated in order to maximize the diagnostic accuracy in patients with PCOS. Sensitivity, specificity, PPV, and NPV were indicated for the best combinations containing 2, 3 or 4 steroid metabolites. The best single discriminating steroid was androstanediol. The best combination to diagnose PCOS contained four of the forty measured metabolites, namely androstanediol, estriol, cortisol and 20βDHcortisone with AUC 0.961 (95% CI 0.926 to 0.995), sensitivity 90.2% (95% CI 76.9 to 97.3), specificity 90.8% (95% CI 81.0 to 96.5), PPV 86.0% (95% CI 72.1 to 94.7), and NPV 93.7% (95% CI 84.5 to 98.2). PCOS shows a specific 24h urinary steroid profile, if neglected metabolites are included in the analysis and non-conventional data analysis applied. PCOS does not share a profile with hyperandrogenic forms of congenital adrenal hyperplasias due to single steroid enzyme deficiencies. Thus PCOS diagnosis by exclusion may no longer be warranted. Whether these findings also apply to spot urine and serum, remains to be tested as a next step towards routine clinical applicability

Gene regulation contributes to explain the impact of early life socioeconomic disadvantage on adult inflammatory levels in two cohort studies

Individuals experiencing socioeconomic disadvantage in childhood have a higher rate of inflammation-related diseases decades later. Little is known about the mechanisms linking early life experiences to the functioning of the immune system in adulthood. To address this, we explore the relationship across social-to-biological layers of early life social exposures on levels of adulthood inflammation and the mediating role of gene regulatory mechanisms, epigenetic and transcriptomic profiling from blood, in 2,329 individuals from two European cohort studies. Consistently across both studies, we find transcriptional activity explains a substantive proportion (78% and 26%) of the estimated effect of early life disadvantaged social exposures on levels of adulthood inflammation. Furthermore, we show that mechanisms other than cis DNA methylation may regulate those transcriptional fingerprints. These results further our understanding of social-to-biological transitions by pinpointing the role of gene regulation that cannot fully be explained by differential cis DNA methylation

Dinstinct phenotype of kidney stone formers with renal phosphate leak

Background: Hypercalciuria is the most frequent metabolic disorder encountered in kidney stone formers (SF). Reduced renal phosphate reabsorption (i.e. renal phosphate leak) was proposed to be a driver of hypercalciuria in calcareous stone formers. However, the phenotype of SF with renal phosphate leak remains poorly defined, and the association of renal phosphate leak with stone history, stone composition and bone mineral density (BMD) has not been studied. Methods: To fill these knowledge gaps, we conducted a cross-sectional analysis in a cohort of 555 idiopathic calcareous SF. The ratio of tubular maximum reabsorption of phosphate to glomerular filtration rate (TmP/GFR) was used to evaluate renal phosphate transport. Results: Multivariable regression analyses revealed a negative association of parathyroid hormone (PTH), a positive association of 25(OH) and 1,25(OH)2 vitamin D but no association of Fibroblast growth factor 23 (FGF23) with TmP/GFR. SF with low TmP/GFR had their first stone event at a younger age and were more likely to have a positive family history of kidney stones. In addition, urinary calcium excretion and prevalence of brushite stones were significantly higher in SF with low TmP/GFR. However, BMD, measured by dual-energy x-ray absorptiometry, was not associated with TmP/GFR in stone formers. Conclusions: Renal phosphate handling has a strong heritable component in SF and correlates with PTH, 25(OH) Vitamin D and 1,25(OH)2 vitamin D, but not with FGF23 levels. Furthermore, a low TmP/GFR (i.e. a renal phosphate leak) is associated with higher urinary calcium excretion and an increased prevalence of brushite stones