Nephrolithiasis, stone composition, meteorology, and seasons in Malta: Is there any connection?

Influence of Dietary Heritage in a Restricted Geographic Area and Role of Food Additives on Risk of Recurrent Kidney Stone

Dietary factors may be implicated in the formation of kidney stones and should be closely monitored. To achieve this aim, patients are routinely assessed by means of generic dietary recall, a tool widely used by authors in a range of extensive patient populations to record food intake; the findings obtained, however, may be skewed due to dietary variations and underestimation of the effect of food additives. Fifty Frequent Kidney Stone Formers (FKSFs, mean age: 54.3 ± 13.9 years) with normal kidney function, absence of comorbidities, and reliable compliance were selected from a total of 68 patients' resident in Sardinia, an Italian island where genetic admixtures have been relatively rare for generations. The study, conducted from 1 January 2020 to 31 December 2023, was aimed at assessing nutritional values based on the meticulous recording of food quantities, quality, and potential modifications related to food preparation. Patients were selected during an initial clinical check-up and all efforts made to ensure they were capable of reliably recording all food and drinks consumed. A seven-day food diary was provided in which food and drink intake and their impact on 24 h urine output was recorded. The following parameters were measured in both foods and urine output: citrates, oxalates, calcium, phosphorous, uric acid, proteins and nitrogen compounds, magnesium, sulfates, potassium, carbohydrates, free fatty acids. Study outcomes established the presence of hypocitraturia, hyperoxaluria, hypercalciuria, and moderately high levels of nitrogen compounds. Univariate analysis followed by multivariate analysis for further confirmation were performed and the following observations made. Citrate intake correlated with citraturia but did not promote oxaluria; calcium intake promoted onset of sulfaturia, azoturia, and ammoniuria, whilst magnesium correlated with magnesiuria but not with oxaluria, calciuria, phosphaturia, and azoturia; sulfate intake elicited onset of azoturia but not kaliuresis; potassium intake promoted oxaluria and protein intake resulted in onset of ammoniuria and azoturia. (A) The chemical composition of urine based on dietary intake is hard to predict without taking into account the presence of dietary and urinary interferents; (B) the geographic isolation of patients studied underlines the importance of epigenetics in maintaining a traditional dietary heritage. (C) Moreover, the widespread use of food additives should consistently be taken into account to ensure a correct diagnosis of FKSF and set up a valid treatment plan.

Sex-Specific Association of Ambient Temperature With Urine Biomarkers in Southwest Coastal Bangladesh

Introduction

Men are vulnerable to ambient heat-related kidney disease burden; however, limited evidence exists on how vulnerable women are when exposed to high ambient heat. We evaluated the sex-specific association between ambient temperature and urine electrolytes, and 24-hour urine total protein, and volume.

Methods

We pooled a longitudinal 5624 person-visits data of 1175 participants' concentration and 24-hour excretion of urine electrolytes and other biomarkers (24-hour urine total protein and volume) from southwest coastal Bangladesh (Khulna, Satkhira, and Mongla districts) during November 2016 to April 2017. We then spatiotemporally linked ambient temperature data from local weather stations to participants' health outcomes. For evaluating the relationships between average ambient temperature and urine electrolytes and other biomarkers, we plotted confounder-adjusted restricted cubic spline (RCS) plots using participant-level, household-level, and community-level random intercepts. We then used piece-wise linear mixed-effects models for different ambient temperature segments determined by inflection points in RCS plots and reported the maximum likelihood estimates and cluster robust standard errors. By applying interaction terms for sex and ambient temperature, we determined the overall significance using the Wald test. Bonferroni correction was used for multiple comparisons.

Results

The RCS plots demonstrated nonlinear associations between ambient heat and urine biomarkers for males and females. Piecewise linear mixed-effects models suggested that sex did not modify the relationship of ambient temperature with any of the urine parameters after Bonferroni correction (P < 0.004).

Conclusion

Our findings suggest that women are as susceptible to the effects of high ambient temperature exposure as men.

Cystine Urolithiasis in Ferrets

Urolithiasis in captive domestic ferrets has previously been predominantly struvite uroliths, although more recent laboratory submissions show a shift to predominantly cystine uroliths. Genetic mutations for cystinuria have been identified in dogs, and it is suspected that underlying genetic mutations are partly responsible for this disease in ferrets. Currently, surgery remains the only definitive treatment of cystine urolithiasis in ferrets, since dietary dissolution protocols have not been thoroughly explored. Despite this, medical management with dietary and urinary manipulation should be considered for use in ferrets postoperatively based on principles of cystine urolithiasis management in dogs adapted for ferrets.

Influence of socioeconomic disparities, temperature and humidity in kidney stone composition

INTRODUCTION

Large variations in demographic, economic and environmental factors might influence the worldwide distribution of urolithiasis, but scarce data are available concerning their associations with stone composition. We aimed to evaluate the frequency and composition of kidney stones and their associations with temperature, humidity, and human development index (HDI).

MATERIALS AND METHODS

A total of 1,158 stones from distinct patients (47±14 years old, male/female 2:1) were included. The mean annual temperature and relative humidity of each town were considered separately.

RESULTS

Calcium oxalate monohydrate (COM) was disclosed in 38.8% of patients, calcium oxalate dihydrate (COD) in 22.1%, mixed COD/apatite in 9.4%, pure apatite in 1.9%, brushite in 1.8%, struvite in 8.3%, pure uric acid in 11.1%, mixed uric acid/COM in 5.6%, and cystine/rare types in 0.8%. Mean HDI of all pooled cities was 0.780±0.03. However, people living in HDI<0.800 regions had twice the odds of having a struvite stone versus those living in HDI>0.800 (OR=2.14, 95% CI 1.11-4.11). Furthermore, a progressive increase in the struvite stones frequency from 4.5 to 22.8% was detected from HDI>0.800 through HDI<0.700. No significant difference for other stone types was disclosed. Separate logistic regression models assessed the association of each stone composition with gender, temperature, humidity and HDI as covariates.

CONCLUSION

Patients living in low HDI areas are more prone to develop struvite stones, possibly due to lower access to healthcare. Temperature and humidity did not represent a specific risk factor for any stone type in the present sample.

Variation in Kidney Stone Composition Within the United States

INTRODUCTION AND OBJECTIVES

Kidney stone incidence has been known to vary with temperature and climate. However, little is known about any variation in the composition of kidney stones across different regions of the United States. We attempted to evaluate whether stone composition changes depending on region.

METHODS

We were given access to de-identified data from LABCORPs database of kidney stone composition from August 1, 2016, to October 24, 2016, for states in seven representative areas of the country: Virginia, Minnesota, Florida, Arizona, Colorado, California, and Texas. We analyzed each component of kidney stones with optical microscopy supplemented with Fourier-transform infrared spectroscopy (FT-IR) spectrometry using both the percentage of the stone that was composed of that component as well as a binary variable coded none vs any. Univariate associations between component and state were examined using chi-square or Fisher's exact test for the binary indicator, and analysis of variance for the continuous percentage. The same set of analyses was used for decade of age vs each component. The association between age and state was examined using analysis of variance.

RESULTS

Data were available for 4335 kidney stones, from patients in the 7 states mentioned. The most common components across all stones were calcium oxalate monohydrate and calcium phosphate (both present in 93% of stones), calcium oxalate dihydrate (in 57% of stones), and uric acid (in 12% of stones). Stone composition did not vary widely across regions, except for uric acid stones, which were more prevalent in Florida compared to other states, with an odds ratio of 1.43 (95% confidence interval 1.12, 1.83).

CONCLUSION

Kidney stone composition does not vary widely by region within the United States. Although temperature and humidity play a role in stone incidence, there does not appear to be a large variation between different climates, with the exception of uric acid stone formation in Florida.

[Epidemiology of urolithiasis in French West Indies: A retrospective study]

INTRODUCTION

The incidence of urolithiasis is increasing with dietary changes especially in developed countries. Guadeloupe is a French department overseas where western diet meets traditional local food. The objective was to describe and analyze the epidemiology of urolithiasis in Guadeloupe.

MATERIAL AND METHODS

We conducted a retrospective single-center study throughout the year 2015 on patients hospitalized for urolithiasis at University Hospital of Pointe-à-Pitre. Data of the patients, treatments performed and the types of stones were recorded. According to their mineral content, groups were composed.

RESULTS

In total, 165 patients were included. The sex ratio was 1.61. The median body mass index (BMI) was 26.5kg/m². The most common stone was oxalocalcic (64.7%). Mixed stones (24.7%) were in second place. There were only 3.5% of uric acid urolithiasis. Calcium oxalate stones were predominantly monohydrate. The oxalocalcic stones were significantly more frequent in men (80% versus 47.5%, P=0.01) and in the age group over 50 years old (72.2% versus 51.6%, P=0.04). There was no association between the type of stone and the BMI.

CONCLUSION

Epidemiology of urolithiasis in our French Caribbean island is, therefore, similar to continental France. However, our population is distinguished by the proportion of women affected and by the different proportions among each type of stone. Other studies on larger samples are needed to study these specificities.

LEVEL OF EVIDENCE

4.