Sex Differences and the Risk of Kidney Stones.

A significant increase in the prevalence of kidney stones has been observed worldwide. In the past decades, this expansion was more pronounced among women than men. The precise mechanisms involved in the differences in the risk profile of stone disease between men and women have not been fully elucidated. Diet and lifestyle only partially can explain the differences, and the combination of factors such as the influence of sex hormones, genetics, and disorders in acid-base handling and urine pH, as well as differences in calcium tubular reabsorption and stone composition in men and women, may contribute to differences in the risk profile. In this review, we summarize the sex differences in the pathophysiologic basis of kidney stones, which may contribute to a more focused approach.

Temporal Trends of Dietary Risk Factors after a Diagnosis of Kidney Stones.

BACKGROUND AND OBJECTIVES: Diet is an important contributor to kidney stone formation, but there are limited data regarding long-term changes in dietary factors after a kidney stone. DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS: We analyzed data from three longitudinal cohorts, the Health Professionals Follow-Up Study and Nurses' Health Study I and II, comparing changes in dietary factors in participants with and without kidney stones during follow-up. The daily intake of dietary calcium, supplemental calcium, animal protein, caffeine, fructose, potassium, sodium, oxalate, phytate, vitamin D, vitamin C, sugar-sweetened beverages, fluids, net endogenous acid production, and Dietary Approaches to Stop Hypertension score were assessed by repeat food frequency questionnaires and computed as absolute differences; a difference-in-differences approach was used to account for temporal changes using data from participants without kidney stones from the same calendar period. RESULTS: Included were 184,398 participants with no history of kidney stones, 7095 of whom became confirmed stone formers. Several intakes changed significantly over time in stone formers, with some showing a relative increase up to 8 years later, including caffeine (difference in differences, 8.8 mg/d; 95% confidence interval [95% CI], 3.4 to 14.1), potassium (23.4 mg/d; 95% CI, 4.6 to 42.3), phytate (12.1 mg/d; 95% CI, 2.5 to 21.7), sodium (43.1 mg/d; 95% CI, 19.8 to 66.5), and fluids (47.1 ml/d; 95% CI, 22.7 to 71.5). Other dietary factors showed a significant decrease, such as oxalate (-7.3 mg/d; 95% CI, -11.4 to -3.2), vitamin C (-34.2 mg/d; 95% CI, -48.8 to -19.6), and vitamin D (-18.0 IU/d; 95% CI, -27.9 to -8.0). A significant reduction was observed in sugar-sweetened beverages intake of -0.5 (95% CI, -0.8 to -0.3) and -1.4 (95% CI, -1.8 to -1.0) servings per week and supplemental calcium of -105.1 (95% CI, -135.4 to -74.7) and -69.4 (95% CI, -95.4 to -43.4) mg/d for women from Nurses' Health Study I and II, respectively. Animal protein, dietary calcium, fructose intake, Dietary Approaches to Stop Hypertension score, and net endogenous acid production did not change significantly over time. CONCLUSIONS: After the first episode of a kidney stone, mild and inconsistent changes were observed concerning dietary factors associated with kidney stone formation.

Thiazide and thiazide-like diuretics in nephrolithiasis / Diuréticos tiazídicos e tiazídicos-like na nefrolitíase

Abstract Thiazide and thiazide-like diuretics are widely used for the management of hypercalciuria among stone-forming patients. Although the effects of different thiazides should be relatively similar in terms of prevention of stone recurrence, their potency and side effects may differ. However, there is scarce data concerning the metabolic and bone effects of these agents among recurrent nephrolithiasis patients with hypercalciuria. The aim of this update article was to compare our experience in the use of thiazide and thiazide- like diuretics with that of the current literature, concerning their anticalciuric properties and consequent reduction of recurrent stone formation. Their impact on bone mass and potential side effects were also discussed.

Resumo Diuréticos tiazídicos e tiazídicos-like são amplamente usados para o tratamento da hipercalciúria em pacientes com formação de cálculos. Embora os efeitos dos diferentes tiazídicos devam ser relativamente semelhantes em termos de prevenção da recorrência do cálculo, sua potência e efeitos colaterais podem ser diferentes. No entanto, há poucos dados sobre os efeitos metabólicos e ósseos desses agentes em pacientes com nefrolitíase recorrente com hipercalciúria. O objetivo deste artigo de atualização foi comparar nossa experiência quanto ao uso de tiazídicos e tiazídicos-like com a publicada na literatura atual, no que diz respeito às suas propriedades anticalciúricas e consequente redução da formação de cálculos recorrentes. Discutimos também seu impacto na massa óssea e potenciais efeitos colaterais.

Thiazide and thiazide-like diuretics in nephrolithiasis.

Thiazide and thiazide-like diuretics are widely used for the management of hypercalciuria among stone-forming patients. Although the effects of different thiazides should be relatively similar in terms of prevention of stone recurrence, their potency and side effects may differ. However, there is scarce data concerning the metabolic and bone effects of these agents among recurrent nephrolithiasis patients with hypercalciuria. The aim of this update article was to compare our experience in the use of thiazide and thiazide- like diuretics with that of the current literature, concerning their anticalciuric properties and consequent reduction of recurrent stone formation. Their impact on bone mass and potential side effects were also discussed.

Comparison of Supersaturation Outputs from Different Programs and Their Application in Testing Correspondence with Kidney Stone Composition.

Introduction: Relative supersaturation (SS) for calcium oxalate (CaOx), calcium phosphate (CaP), and uric acid (UA) has been used for assessing urinary crystallization and estimated by programs, including EQUIL, Joint Expert Speciation System (JESS), and Lithorisk. We compared outputs from these programs and their correspondence with stone composition. Materials and Methods: SS of CaOx, CaP, and UA, using EQUIL, JESS, and Lithorisk were calculated from stone-forming patients. Pearson correlation coefficients were used to ascertain the correspondence between the outputs. Fractional regression models evaluated the relationship between SS and the percentage of each compound in the stones. Results: Two hundred eleven patients were included. Pearson correlation coefficients for CaOx (r ≥ 0.96), CaP (r ≥ 0.99), and UA SS (r ≥ 0.99) showed a high correspondence between all programs. We observed a significant correspondence between CaOx SS and the percentage of CaOx dihydrate in the stone (p < 0.001), as well as between the percentage of brushite and apatite and CaP SS. UA SS showed the strongest correspondence with the percentage of UA in the stones (p < 0.001). Conclusions: Good correlation between EQUIL, JESS, and Lithorisk was observed and good correspondence with stone composition. The magnitude of the association demonstrated by fractional regression models supports evidence for applying SS in clinical practice.

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.

Bartter syndrome: causes, diagnosis, and treatment.

Bartter syndrome is an inherited renal tubular disorder caused by a defective salt reabsorption in the thick ascending limb of loop of Henle, resulting in salt wasting, hypokalemia, and metabolic alkalosis. Mutations of several genes encoding the transporters and channels involved in salt reabsorption in the thick ascending limb cause different types of Bartter syndrome. A poor phenotype-genotype relationship due to the interaction with other cotransporters and different degrees of compensation through alternative pathways is currently reported. However, phenotypic identification still remains the first step to guide the suspicion of Bartter syndrome. Given the rarity of the syndrome, and the lack of genetic characterization in most cases, limited clinical evidence for treatment is available and the therapy is based mainly on the comprehension of renal physiology and relies on the physician's personal experiences. A better understanding of the mutated channels and transporters could possibly generate targets for specific treatment in the future, also encompassing drugs aiming to correct deficiencies in folding or plasma membrane expression of the mutated proteins.