The Vitamin D Metabolite Diagnostic Ratio Associates With Phenotypic Traits of Idiopathic Hypercalciuria.

Introduction: Underlying mechanisms for hypercalciuria remain unknown in most cases; thus, the designation "idiopathic." We hypothesized that the vitamin D-inactivating enzyme, CYP24A1 contributes to the pathogenesis of hypercalciuria in kidney stone formers. Methods: We conducted association analyses between CYP24A1 activity, estimated by the vitamin D metabolite diagnostic ratio (25(OH) vitamin D3/total 24,25 (OH)2 vitamin D ratio; VMDR), and the phenotype of participants in 2 observational cohorts of kidney stone formers, the Swiss Kidney Stone Cohort (SKSC) and the Bern Kidney Stone Registry (BKSR). Circulating 25(OH)- and 24,25 (OH)2 vitamin D were quantified using a validated liquid chromatography tandem mass spectrometry assay. Results: A total of 974 participants were included in the analysis. We found a positive association of VMDR (and hence negative association of CYP24A1 activity) with total (ß 0.009 mmol/l; 95% confidence interval [CI]: 0.002, 0.016; P = 0.02) and ionized plasma calcium (ß 0.005 mmol/l; 95% CI: 0.002, 0.008; P < 0.01), absolute and fractional excretion of urinary calcium (ß 0.054 mmol/24h; 95% CI: 0.010, 0.097; P = 0.02 and ß 0.046%; 95% CI: 0.018, 0.074; P < 0.01, respectively). Further, VMDR was associated with an increased likelihood of forming calcium oxalate dihydrate stones (Odds ratio [OR] 1.64; 95% CI: 1.22, 2.35; P < 0.01) and reduced bone mineral density (BMD) at the femoral neck (ß -0.005 g/cm2; 95% CI: -0.010, -0.001; P = 0.04). The described associations became stronger when the analysis was confined to idiopathic calcium stone formers. Conclusion: Our study reveals that CYP24A1 activity, estimated by VMDR, is associated with clinical traits previously linked to idiopathic hypercalciuria.

Corrigendum to "Classifying Hypotonic Hyponatremia by Projected Treatment Effects - A Quantitative 3-Dimensional Framework" [Kidney International Reports Volume 8, Issue 12, December 2023, Pages 2720-2732].

[This corrects the article DOI: 10.1016/j.ekir.2023.09.002.].

Hyponatremia in the Context of Liver Disease.

Hyponatremia is common in patients with liver disease and is associated with increased mortality, morbidity, and a reduced quality of life. In liver transplantation, the inclusion of hyponatremia in organ allocation scores has reduced waitlist mortality. Portal hypertension and the resulting lowering of the effective arterial blood volume are important pathogenetic factors, but in most patients with liver disease, hyponatremia is multifactorial. Treatment requires a multifaceted approach that tries to reduce electrolyte-free water intake, restore urinary dilution, and increase nonelectrolyte solute excretion. Albumin therapy for hyponatremia is a peculiarity of advanced liver disease. Its use appears to be increasing, while the vaptans are currently only given in selected cases. Osmotic demyelination is a special concern in patients with liver disease. Serial checks of serum sodium concentrations and urine volume monitoring are mandatory.

Classifying Hypotonic Hyponatremia by Projected Treatment Effects - A Quantitative 3-Dimensional Framework.

Introduction: The diagnostic algorithms currently used for hypotonic hyponatremia focus primarily on impaired urinary dilution and often neglect the influence of free water intake and solute excretion. We hypothesized that, in each case of hypotonic hyponatremia different pathophysiological mechanisms play a role simultaneously. Methods: Using clinical data of the previous observational Co-Med study, we defined each case of hypotonic hyponatremia concurrently in 3 dimensions as follows: (i) high net free water intake (HNFWI), (ii) impaired dilution of the urine (IDU), and (iii) low nonelectrolyte solute excretion (LNESE). For each dimension, a "standard delta sodium" (sdna) was calculated reflecting the expected difference to the serum sodium concentration, that would result from changing a dimension to a specific and equivalent target level. Results: Results from 279 patients were used for this analysis. With target levels of free water intake and urine osmolality at the fifth percentile, and nonelectrolyte solute excretion at the 95th percentile, median (interquartile range) sdna values were 7.1 (4.8-10.2) for HNFWI, 11.8 (7.0-18.6) for IDU and 2.6 (1.6-4.2) mmol/l per 24 hours for LNESE. Sdna results in individual patients were highest with IDU in 68.5%, HNFWI in 30.8% and 0.7% with LNESE. At an sdna-level of at least 4mmol/l per 24 hours, the prevalence of HNFWI was 78.9%, IDU 87.1%, and LNESE 26.5%. 77.5% of patients had 2 or all 3 mechanisms present. Hyponatremia was mostly multifactorial in subgroups according to classic categories of hyponatremia and typical comorbidities as well. Conclusion: Hypotonic hyponatremia can be quantitatively defined by 3 dimensions. Most cases should be considered multifactorial.

Differences in the Food Consumption Between Kidney Stone Formers and Nonformers 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 nonstone 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 computed tomography-scan proven nonstone 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 nonstone 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 (ß coeff[95% CI] = - 0.23[- 0.41; - 0.06]), coffee (ß coeff = - 0.21[- 0.37; - 0.05]), teas (ß coeff = - 0.52[- 0.92; - 0.11]) and alcoholic beverages (ß 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 nonstone formers. For the other food groups, stone formers and nonformers 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.

Hydrochlorothiazide and Prevention of Kidney-Stone Recurrence.

BACKGROUND: Nephrolithiasis is one of the most common conditions affecting the kidney and is characterized by a high risk of recurrence. Thiazide diuretic agents are widely used for prevention of the recurrence of kidney stones, but data regarding the efficacy of such agents as compared with placebo are limited. Furthermore, dose-response data are also limited. METHODS: In this double-blind trial, we randomly assigned patients with recurrent calcium-containing kidney stones to receive hydrochlorothiazide at a dose of 12.5 mg, 25 mg, or 50 mg once daily or placebo once daily. The main objective was to investigate the dose-response effect for the primary end point, a composite of symptomatic or radiologic recurrence of kidney stones. Radiologic recurrence was defined as the appearance of new stones on imaging or the enlargement of preexisting stones that had been observed on the baseline image. Safety was also assessed. RESULTS: In all, 416 patients underwent randomization and were followed for a median of 2.9 years. A primary end-point event occurred in 60 of 102 patients (59%) in the placebo group, in 62 of 105 patients (59%) in the 12.5-mg hydrochlorothiazide group (rate ratio vs. placebo, 1.33; 95% confidence interval [CI], 0.92 to 1.93), in 61 of 108 patients (56%) in the 25-mg group (rate ratio, 1.24; 95% CI, 0.86 to 1.79), and in 49 of 101 patients (49%) in the 50-mg group (rate ratio, 0.92; 95% CI, 0.63 to 1.36). There was no relation between the hydrochlorothiazide dose and the occurrence of a primary end-point event (P = 0.66). Hypokalemia, gout, new-onset diabetes mellitus, skin allergy, and a plasma creatinine level exceeding 150% of the baseline level were more common among patients who received hydrochlorothiazide than among those who received placebo. CONCLUSIONS: Among patients with recurrent kidney stones, the incidence of recurrence did not appear to differ substantially among patients receiving hydrochlorothiazide once daily at a dose of 12.5 mg, 25 mg, or 50 mg or placebo once daily. (Funded by the Swiss National Science Foundation and Inselspital; NOSTONE ClinicalTrials.gov number, NCT03057431.).

The Swiss Kidney Stone Cohort: A Longitudinal, Multicentric, Observational Cohort to Study Course and Causes of Kidney Stone Disease in Switzerland.

BACKGROUND: 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 lifestyle risk factors, and the dissection of these factors is complex. METHODS: The Swiss Kidney Stone Cohort (SKSC) is an investigator-initiated prospective, multicentric 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. SKSC comprises 782 adult patients (age >18 years) 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-h urine samples, and genetic data. Biosamples are stored at a dedicated biobank. Information on diet and dietary habits was collected through food frequency questionnaires and standardized recall interviews by trained dieticians with the Globodiet software. CONCLUSION: SKSC provides a unique opportunity and resource to further study cause and course of kidney disease in a large population with data and samples collected of a homogeneous collective of patients throughout the whole Swiss population.

Clinical spectrum of gross haematuria following SARS-CoV-2 vaccination with mRNA vaccines.

Background: Novel messenger RNA (mRNA)-based vaccines play an important role in current vaccination campaigns against SARS-CoV-2. They are highly efficacious and generally well tolerated. Vaccination in patients with immune-mediated kidney diseases is recommended. A number of cases with de novo or relapsing glomerulonephritis shortly after vaccine application have been reported, some of which presented with gross haematuria. Methods: We collected 10 cases of macrohaematuria following mRNA-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination at our tertiary care institution and referring centres. Additionally, we pooled all 25 published cases from the literature with ours to analyse their clinical characteristics. Results: Most macrohaematuria episodes (72.2%) began within 2 days after vaccination, the majority after the second dose. In some individuals, repeated episodes occurred after subsequent doses of the same vaccine. A total of 65.7% of patients never had macrohaematuria before. A total of 45.7% were known to suffer from immunoglobulin A nephropathy (IgAN); the rest had no prior renal diagnosis. IgAN was the most frequent new diagnosis, but anti-neutrophil cytoplasmic antibody-associated vasculitis and anti-glomerular basement membrane disease were also identified. Acute kidney injury (AKI) occurred in 28.6% of patients, with an increase in serum creatinine not meeting Kidney Disease: Improving Global Outcomes AKI criteria in 28.6%. Treatment ranged from conservative management, renin-angiotensin-aldosterone system inhibitors, steroids and cyclophosphamide to plasmapheresis. While renal outcomes were mainly favourable in isolated IgAN, they were poor in patients with additional or isolated small vessel vasculitis. Conclusion: Awareness of gross haematuria after SARS-CoV-2 vaccination is important. Close follow-up and additional work up, particularly in individuals without known underlying kidney disease or worsening renal function, is essential. For patients with vaccine-associated macrohaematuria, an alternative vaccine class might be considered for subsequent vaccinations.

Insights from the Hereditary Thrombotic Thrombocytopenic Purpura Registry: Discussion of Key Findings Based on Individual Cases from Switzerland.

The Hereditary TTP Registry is an international cohort study for patients with a confirmed or suspected diagnosis of hereditary thrombotic thrombocytopenic purpura (hTTP) and their family members. Hereditary TTP is an ultra-rare blood disorder (prevalence of ∼1-2 cases per million), the result of autosomal-recessively inherited congenital ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) deficiency (ADAMTS13 activity <10% of the normal), and associated with yet many unanswered questions. Until December 2017, the Hereditary TTP Registry had enrolled 123 confirmed hTTP patients. Their median age at disease onset was 4.5 years (range: 0-70) and at clinical diagnosis 16.7 years (range: 0-69), a difference that highlights the existing awareness gap in recognizing hTTP. The systematic collection of clinical data of individual patients revealed their substantial baseline comorbidities, as a consequence of recurring TTP episodes in the past. Most notable was the high proportion of patients having suffered from premature arterial thrombotic events, mainly transient ischemic attacks, ischemic strokes, and to a lesser extent myocardial infarctions. At 40 to 50 years of age and above, more than 50% of patients had suffered from at least one such event, and many had experienced arterial thrombotic events despite regular plasma infusions every 2 to 3 weeks that supplements the missing plasma ADAMTS13. The article by van Dorland et al. (Haematologica 2019;104(10):2107-2115) and the ongoing Hereditary TTP Registry cohort study were recognized with the Günter Landbeck Excellence Award at the 50th Hemophilia Symposium in Hamburg in November 2019, the reason to present the Hereditary TTP Registry in more detail here.

Efficacy of standard and low dose hydrochlorothiazide in the recurrence prevention of calcium nephrolithiasis (NOSTONE trial): protocol for a randomized double-blind placebo-controlled trial.

BACKGROUND: Nephrolithiasis is a global healthcare problem with a current lifetime risk of 18.8% in men and 9.4% in women. Given the high cost of medical treatments and surgical interventions as well as the morbidity related to symptomatic stone disease, medical prophylaxis for stone recurrence is an attractive approach. Thiazide diuretics have been the cornerstone of pharmacologic metaphylaxis for more than 40 years. However, evidence for benefits and harms of thiazides in the prevention of calcium containing kidney stones in general remains unclear. In addition, the efficacy of the currently employed low dose thiazide regimens to prevent stone recurrence is not known. METHODS: The NOSTONE trial is an investigator-initiated 3-year prospective, multicenter, double-blind, placebo-controlled trial to assess the efficacy of standard and low dose hydrochlorothiazide treatment in the recurrence prevention of calcium containing kidney stones. We plan to include 416 adult (≥ 18 years) patients with recurrent (≥ 2 stone episodes in the last 10 years) calcium containing kidney stones (containing ≥50% of calcium oxalate, calcium phosphate or a mixture of both). Patients will be randomly allocated to 50 mg or 25 mg or 12.5 mg hydrochlorothiazide or placebo. The primary outcome will be incidence of stone recurrence (a composite of symptomatic or radiologic recurrence). Secondary outcomes will be individual components of the composite primary outcome, safety and tolerability of hydrochlorothiazide treatment, changes in urinary biochemistry elicited by hydrochlorothiazide treatment and impact of baseline disease severity, biochemical abnormalities and stone composition on treatment response. DISCUSSION: The NOSTONE study will provide long-sought information on the efficacy of hydrochlorothiazide in the recurrence prevention of calcium containing kidney stones. Strengths of the study include the randomized, double-blind and placebo-controlled design, the large amount of patients studied, the employment of high sensitivity and high specificity imaging and the exclusive public funding support. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03057431 . Registered on February 20 2017.

Procalcitonin and pyuria-based algorithm reduces antibiotic use in urinary tract infections: a randomized controlled trial.

BACKGROUND: Urinary tract infections (UTIs) are common drivers of antibiotic use. The minimal effective duration of antibiotic therapy for UTIs is unknown, but any reduction is important to diminish selection pressure for antibiotic resistance, costs, and drug-related side-effects. The aim of this study was to investigate whether an algorithm based on procalcitonin (PCT) and quantitative pyuria reduces antibiotic exposure. METHODS: From April 2012 to March 2014, we conducted a factorial design randomized controlled open-label trial. Immunocompetent adults with community-acquired non-catheter-related UTI were enrolled in the emergency department of a tertiary-care 600-bed hospital in northwestern Switzerland. Clinical presentation was used to guide initiation and duration of antibiotic therapy according to current guidelines (control group) or with a PCT-pyuria-based algorithm (PCT-pyuria group). The primary endpoint was overall antibiotic exposure within 90 days. Secondary endpoints included duration of the initial antibiotic therapy, persistent infection 7 days after end of therapy and 30 days after enrollment, recurrence and rehospitalizations within 90 days. RESULTS: Overall, 394 patients were screened, 228 met predefined exclusion criteria, 30 declined to participate, and 11 were not eligible. Of these, 125 (76% women) were enrolled in the intention-to-treat (ITT) analysis and 96 patients with microbiologically confirmed UTI constituted the per protocol group; 84 of 125 (67%) patients had a febrile UTI, 28 (22%) had bacteremia, 5 (4%) died, and 3 (2%) were lost to follow-up. Overall antibiotic exposure within 90 days was shorter in the PCT-pyuria group than in the control group (median 7.0 [IQR, 5.0-14.0] vs. 10.0 [IQR, 7.0-16.0] days, P = 0.011) in the ITT analysis. Mortality, rates of persistent infections, recurrences, and rehospitalizations were not different. CONCLUSIONS: A PCT-pyuria-based algorithm reduced antibiotic exposure by 30% when compared to current guidelines without apparent negative effects on clinical outcomes.