Nephrocalcinosis and hyperlipidemia in rats fed a cholesterol- and fat-rich diet: association with hyperoxaluria, altered kidney and bone minerals, and renal tissue phospholipid-calcium interaction

Relationship between remnant cholesterol and risk of kidney stones in U.S. Adults: a 2007-2016 NHANES analysis

PURPOSE

Remnant cholesterol (RC) is the cholesterol content of triglyceride-rich lipoproteins. This study aimed to investigate the association between RC levels and kidney stones in U.S. adults.

METHODS

Data were obtained from the 2007 to 2016 National Health and Nutrition Examination Survey (NHANES). A total of 10,551 participants with complete data were included and analyzed in this study. Univariate and multivariate logistic regression analysis, restricted cubic spline function, subgroup analysis and mediation analysis were preformed to estimate the independent relationship between RC levels and kidney stones.

RESULTS

Participants with stone formation had higher levels of RC than those with without stone formation (25.78 ± 13.83 vs 23.27 ± 13.04, p< 0.001). The results of logistic regression analysis and dose-response risk curves revealed a positive nonlinear association between RC levels and risk of kidney stones [univariate: adjusted odds ratio (aOR) =2.388, 95% CI: 1.797-3.173, p< 0.001; multivariate: aOR = 1.424, 95% CI: 1.050-1.929, p = 0.023]. Compared with the discordantly low RC group, the discordantly high RC group was associated with increased risk of kidney stones (aOR = 1.185, 95% CI: 1.013-1.386, p= 0.034). Similar results were demonstrated according to the discordance of different clinical cut points. And metabolic syndrome parameters and vitamin D levels parallelly mediated the association between RC and kidney stone risk.

CONCLUSIONS

Higher RC levels were independently associated with an increased risk of kidney stone incidence.

Atorvastatin Decreases Renal Calcium Oxalate Stone Deposits by Enhancing Renal Osteopontin Expression in Hyperoxaluric Stone-Forming Rats Fed a High-Fat Diet

Calcium oxalate (CaOx) is the major constituent of kidney stones. Growing evidence shows a close connection between hyperlipidemia, cardiovascular disease (CVD), and the formation of kidney stones. Owing to their antioxidant properties, statins control hyperlipidemia and may ameliorate CaOx stone formation. The present study was designed to investigate the suppressive effects of statins on CaOx urolithiasis and their potential mechanism. We used rats fed a high-fat diet (HFD) to achieve hyperlipidemia (HL) and hydroxyproline (HP) water to establish a hyperoxaluric CaOx nephrolithiasis model; the animals were administered statins (A) for 28 days. The rats were divided into eight groups treated or not with A, i.e., Control, HP, HL, HL + HP. HL aggravated urinary calcium crystallization compared to the control. Due to increased expression of renal osteopontin (OPN), a key anti-lithic protein, and reduced free radical production, the calcium crystals in the urinary bladder increased as renal calcium deposition decreased. The levels of the ion activity product of CaOx (AP(CaOx)) decreased after statins administration, and AP(Calcium phosphate) (CaP) increased, which suggested the dominant calcium crystal composition changed from CaOx to CaP after statin administration. In conclusion, atorvastatin decreases renal CaOx stone deposits by restoring OPN expression in hyperoxaluric rats fed a HFD.

Temporal Relationship Between Changes in Serum Calcium and Hypercholesteremia and Its Impact on Future Brachial-Ankle Pulse Wave Velocity Levels

Background: The high levels of serum calcium and cholesterol are the important risk factors of cardiovascular disease (CVD), which frequently influence each other during the development of CVD. However, few studies have examined their temporal relationship to confirm the precursor, and it is still largely unknown whether and how their temporal relationship would influence the development of CVD. This study aimed to establish the temporal relationship between the changes in serum calcium and cholesterol using the longitudinal cohort data, and examine whether this temporal relationship influenced the arterial elasticity indicated by brachial-ankle pulse wave velocity (baPWV). Methods: This is a cohort study with a sample of 3,292 Chinese participants (aged 20-74 years) with 5.7 years follow-up. Serum calcium and cholesterol were measured at baseline and follow-up survey. The cross-lagged path analysis was used to examine their temporal relationship, and mediation analysis was performed to evaluate the potential mediating effect. Results: The cross-lagged path coefficients (β₂ values) from baseline serum calcium to follow-up cholesterol was significantly greater than the path coefficients (β₁ values) from baseline cholesterol to follow-up serum calcium (β₂ = 0.110 vs. β₁ = 0.047; P = 0.010) after adjusting for the multiple covariates. The path coefficients from baseline serum calcium to follow-up cholesterol in the participants with high baPWV was significantly greater than the participants with low baPWV (β₂ = 0.155 for high baPWV and β₂ = 0.077 for low baPWV, P = 0.028 for the difference between the β₂ values). Moreover, cholesterol partially mediated the association between the higher serum calcium and greater subsequent baPWV values, the percentage of the total effect mediated by cholesterol was estimated at 21.7%. Conclusion: Our findings indicate that increased serum calcium precedes increased in serum cholesterol, and this temporal relationship may contribute to the development of higher baPWV levels.

Association between hyperlipidemia and calcium oxalate lower urinary tract uroliths in dogs

Background

Metabolic syndrome is associated with formation of calcium oxalate (CaOx) uroliths in humans.

Objectives

To investigate the association between obesity and hyperlipidemia with CaOx lower urinary tract uroliths in client‐owned dogs.

Animals

Dogs with (n = 55, U [uroliths]‐dogs) and without (n = 39, UF [uroliths‐free]‐dogs) CaOx lower urinary tract uroliths.

Methods

Case‐control study. U‐dogs were retrospectively enrolled and compared to UF‐dogs. Body condition score (BCS; 1‐9 scoring scale), serum triglyceride (TG) and total cholesterol (CH) concentrations and glycemia (after >12‐hour food withholding) were recorded in both groups.

Results

On univariate logistic regression, when excluding Miniature Schnauzers, odds of having uroliths increased by a factor of 3.32 (95% CI 1.38‐11.12) for each mmol/L of TG (P = .027), of 39 (95% CI 9.27‐293.22) for each mmol/L of glycemia (P < .0001), and of 2.43 (95% CI 1.45‐4.45) per unit of BCS (P = .002). In multivariable models, the effect of TG was retained when all breeds were included for analysis and odds of having uroliths increased by a factor of 4.34 per mmol/L of TG (95% CI 1.45‐19.99; P = .02).

Conclusions and Clinical Importance

Serum lipid screening in dogs diagnosed with CaOx uroliths might be recommended to improve their medical staging and management.

Molecular Interactions between Dietary Lipids and Bone Tissue during Aging

Age-related bone disorders such as osteoporosis or osteoarthritis are a major public health problem due to the functional disability for millions of people worldwide. Furthermore, fractures are associated with a higher degree of morbidity and mortality in the long term, which generates greater financial and health costs. As the world population becomes older, the incidence of this type of disease increases and this effect seems notably greater in those countries that present a more westernized lifestyle. Thus, increased efforts are directed toward reducing risks that need to focus not only on the prevention of bone diseases, but also on the treatment of persons already afflicted. Evidence is accumulating that dietary lipids play an important role in bone health which results relevant to develop effective interventions for prevent bone diseases or alterations, especially in the elderly segment of the population. This review focuses on evidence about the effects of dietary lipids on bone health and describes possible mechanisms to explain how lipids act on bone metabolism during aging. Little work, however, has been accomplished in humans, so this is a challenge for future research.

Calcium Kidney Stones are Associated with Increased Risk of Carotid Atherosclerosis: The Link between Urinary Stone Risks, Carotid Intima-Media Thickness, and Oxidative Stress Markers

Previous studies have suggested that kidney stone formers are associated with a higher risk of cardiovascular events. To our knowledge, there have been no previous examinations of the relationship between carotid intima-media thickness (IMT) and urinary stone risk factors. This study was aimed toward an investigation of the association between dyslipidemia, IMT, and 24-hour urinalysis in patients with calcium oxalate (CaOx) or calcium phosphate (CaP) stones. We prospectively enrolled 114 patients with kidney stones and 33 controls between January 2016 and August 2016. All patients were divided into four groups, according to the stone compositions—CaOx ≥ 50% group, CaP group, struvite group, and uric acid stones group. Carotid IMT and the carotid score (CS) were evaluated using extracranial carotid artery doppler ultrasonography. The results of a multivariate analysis indicated that a higher serum total cholesterol (TC) and low-density lipoprotein (LDL) were all associated with lower urinary citrate and higher CS in both the CaOx ≥ 50% and CaP groups. Higher serum TC and LDL were also associated with increased serum 8-OHdG levels in both groups. The levels of carotid IMT and CS in the CaOx ≥ 50% and CaP groups were all significantly higher than in the controls. These findings suggest a strong link between dyslipidemia, carotid atherosclerosis, and calcium kidney stone disease.

Impact of dyslipidemia on 24-h urine composition in adults without urolithiasis

PURPOSES

To evaluate the influence of dyslipidemia on 24-h urine composition in adults who were non-stone formers (NF).

METHODS

Samples for 24-h urine composition were analyzed from 584 NF adults without urolithiasis in a national six-city-based epidemiologic study. The samples were divided into groups based on total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL). The groups were compared based on demographic data and each component of 24-h urinalysis.

RESULTS

The numbers of participants in high TG, high TC, high LDL, and low HDL were 106, 175, 147, and 59, respectively. The high TG group had increased urinary excretions of oxalate [mean difference (MD) = 0.032 mmol, 95% confidence interval (CI): 0.000-0.065] and potassium (MD = 4.298 mmol, 95%CI: 0.182-8.414). Increased urinary excretion of calcium (MD = 0.531 mmol, 95%CI: 0.061-1.001), sodium (MD = 41.561 mmol, 95%CI: 9.179-73.942), and chloride (MD = 45.209 mmol, 95%CI: 12.118-78.299) were found in the high TC group. Interestingly, the high LDL group had a decreased urinary excretion of calcium (MD = - 0.573 mmol, 95%CI: -1.048 to - 0.097), oxalate (MD = - 0.038 mmol, 95%CI: -0.07 to - 0.006), sodium (MD = - 53.285 mmol, 95%CI: -85.823 to - 20.748), and chloride (MD = - 55.809 mmol, 95%CI: -89.035 to - 22.583). Increased urinary excretions of citrate (MD = 0.455 mmol, 95%CI: 0.076-0.835) and magnesium (MD = 0.697 mmol, 95%CI: 0.244-1.149) were found in the low HDL group.

CONCLUSIONS

The present study first investigated the effects of dyslipidemia on 24-h urinalysis in NF adults. Of note, high LDL and low HDL were found to be adversely related to kidney stone formation. However, people with high TG and high TC should be cautious of getting kidney stones.

Association between blood lipid profile and urolithiasis: A systematic review and meta-analysis of observational studies

The objective of this study was to pool individual studies regarding the association of blood lipid profiles with urolithiasis to carry out a systematic review and meta-analysis. We searched MEDLINE, PubMed, Embase and Cochrane Library to identify the relevant studies up to November 2017. Studies that met all inclusion criteria were chosen, and a pooled analysis of the odds ratio between urolithiasis and dyslipidemia traits was calculated. A total of 11 observational studies (seven cross-sectional, three cohort, one case-control) with a total of 282 479 participants were examined. The overall pooled analysis of eight studies showed that high triglyceride was associated with increased estimated risk of urolithiasis (odds ratio 1.287, 95% CI 1.073-1.544; P = 0.007). Estimates of the total effect size were consistent in the sensitivity analysis. No evidence of publication bias was detected. The overall pooled analysis of nine studies showed low high-density lipoprotein was weakly associated with increased estimated risk of urolithiasis (odds ratio 1.171, 95% CI 1.010-1.358; P = 0.032). The sensitivity analysis showed conflicting results. No evidence of publication bias was detected. Three studies on the association between any dyslipidemia traits and urolithiasis showed a significant association (odds ratio 1.309, 95% CI 1.202-1.425; P < 0.001). The present meta-analysis showed that patients with higher triglyceride and lower high-density lipoprotein had an increased estimated risk of urolithiasis. A triglyceride-urolithiasis association was found to be more coherent and consistent compared with the high-density lipoprotein-urolithiasis association. Although somewhat contradictory results have been found, the meta-analysis is encouraging for evaluating urolithiasis as a systemic disorder. Further well-designed prospective randomized controlled or cohort studies are necessary to better elucidate the causal association of dyslipidemia and urolithiasis.

Cross-talk between renal lithogenesis and atherosclerosis: an unveiled link between kidney stone formation and cardiovascular diseases

The prevalence of kidney stones and cardiovascular diseases (CVDs) are increasing throughout the world. Both diseases are chronic and characterized by accumulation of oxidized proteins and lipids in the renal tissue and arterial wall, respectively. Emerging studies have revealed a positive association between nephrolithiasis and CVDs. Based on preclinical and clinical evidences, this review discusses: (i) stone forming risk factors, crystal nucleation, aggregation, injury-induced crystal retention, and stone formation, (ii) CVD risk factors such as dyslipidemia, perturbation of gut microbiome, obesity, free radical-induced lipoprotein oxidation, and retention in the arterial wall, subsequent foam cell formation, and atherosclerosis, (iii) mechanism by which stone forming risk factors such as oxalate, calcium, uric acid, and infection contribute toward CVDs, and (iv) how CVD risk factors, such as cholesterol, phospholipids, and uric acid, contribute to kidney stone formation are described.

Marked increase in urinary excretion of apolipoproteins in children with nephrolithiasis associated with hypercalciuria

BACKGROUND

Using a proteomic approach, we aimed to identify and compare the urinary excretion of proteins involved in lipid transport and metabolism in children with kidney stones and hypercalciuria (CAL), hypocitraturia (CIT), and normal metabolic work-up (NM), and in healthy controls (HCs). Additionally, we aimed to confirm these results using ELISA, and to examine the relationship between the urinary excretion of selected proteins with demographic, dietary, blood, and urinary parameters.

METHODS

Prospective, controlled, pilot study of pooled urine from CAL, CIT, and NM versus age- and gender-matched HCs, using liquid chromatography-mass spectrometry. Relative protein abundance was estimated using spectral counting. Results were confirmed by ELISA performed on individual samples.

RESULTS

Of the 1,813 proteins identified, 230 met the above criteria. Of those, 5 proteins (apolipoprotein A-II [APOA2]; apolipoprotein A-IV [APOA4]; apolipoprotein C-III [APOA3]; fatty acid-binding protein, liver [FABPL]; fatty acid-binding protein, adipocyte [FABP4]) involved in lipid metabolism and transport were found in the CAL group, with significant differences compared with HCs. ELISA analysis indicated statistically significant differences in the urinary excretion of APOC3, APOA4, and FABPL in the CAL group compared with HCs. Twenty-four-hour urinary calcium excretion correlated significantly with concentrations of ApoC3 (r = 0.77, p < 0.001), and FABPL (r = 0.80, p = 0.005).

CONCLUSIONS

We provide proteomic data showing increased urinary excretion of lipid metabolism/transport-related proteins in children with kidney stones and hypercalciuria. These findings suggest that abnormalities in lipid metabolism might play a role in kidney stone formation.

Impact of hyperlipidaemia on intermediary metabolism, faecal microbial metabolites and urinary characteristics of lipoprotein lipase deficient vs. normal cats

Findings in humans and rats indicate that hyperlipidaemia may be associated with enhanced endogenous oxalate (Ox) synthesis, which may be relevant for calcium oxalate (CaOx) urolith formation. Moreover, changes in lipid metabolism are proposed to negatively affect gut microbiota. This study aimed to investigate those potential interactions in hyperlipidaemic cats. Therefore, 10 normal control cats and seven lipoprotein lipase (LPL)-deficient cats were fed a low-fat diet for seven weeks. During the last week of the study, cats were housed in metabolic cages to collect urine and faeces. Blood was taken on the last day of the study. The LPL-deficient cats had significantly higher serum triglyceride concentrations than normal cats, while lactate dehydrogenase (LDH) activity was not different. Urinary relative supersaturation with CaOx, urinary Ox, calcium, and citrate excretions, and urine pH did not differ between groups. Lower faecal acetic, propionic and total short-chain fatty acid concentrations were observed in the LPL-deficient cats. In conclusion, hyperlipidaemia does not appear to be a specific risk factor for CaOx urolith formation in cats. In contrast to results in rats, hyperlipidaemia was not accompanied by elevated serum LDH activity. As LDH can synthesise Ox from glycolate or other precursors, this might be one possible explanation for the similar urinary parameters in the LPL-deficient and normal cats. Non-diet-induced hyperlipidaemia was not associated with marked changes in faecal microbial metabolites, suggesting no differences in the composition of the intestinal microbiota.

Effect of long-term high-fat diet intake on peripheral insulin sensibility, blood pressure, and renal function in female rats

BACKGROUND

This study determines whether 8-week high-fat diet (HFD) consumption alters insulin sensitivity, kidney function, and blood pressure (BP) in female rats when compared with standard rodent diet (ND) intake in gender- and age-matched rats.

METHODS

The present study investigates, in female Wistar HanUnib rats, the effect of long-term high-fat fed group (HFD) compared with standard chow on BP by an indirect tail-cuff method using an electrosphygmomanometer, insulin and glucose function, and kidney function by creatinine and lithium clearances.

RESULTS

The current study shows glucose tolerance impairment, as demonstrated by increased fasting blood glucose (ND: 78±2.8 vs. HFD: 87±3.8 mg/dL) associated with reduced insulin secretion (ND: 0.58±0.07 vs. HFD: 0.40±0.03 ng/mL) in 8-week female HFD-treated rats. The incremental area under the curve (AUC, ND: 1,4558.0±536.0 vs. HFD: 1,6507.8±661.9), homeostasis model assessment of insulin resistance (HOMA-IR) index, and the first-order rate constant for the disappearance of glucose (Kitt) were significantly enhanced in 8-week HFD-treated rats compared with age-matched ND group (respectively, P=0.03, P=0.002, and P<0.0001). The current study also shows a significantly higher systolic BP measured in 5 and 8 weeks posttreatment in HFD (5-week HFD-treated: 155.25±10.54 mmHg and 8-week HFD-treated: 165±5.8 mmHg) (P=0.0001), when compared to BP values in 5-week ND, 137±4.24 mmHg and 8-week ND, 131.75±5.8 mmHg age-matched group. Otherwise, the glomerular filtration rate and renal sodium handling evaluated by FENa, FEPNa and FEPPNa, were unchanged in both groups.

CONCLUSION

We may conclude that 8-week female HFD-fed rats compared with ND group stimulate harmful effects, such as BP rise and peripheral glucose intolerance. The increased BP occurs through insulin resistance and supposedly decreased vasodilatation response without any change on renal function.

Identification of the differentially expressed genes associated with familial combined hyperlipidemia using bioinformatics analysis

The aim of the present study was to screen the differentially expressed genes (DEGs) associated with familial combined hyperlipidemia (FCHL) and examine the changing patterns. The transcription profile of GSE18965 was obtained from the NCBI Gene Expression Omnibus database, including 12 FCHL samples and 12 control specimens. The DEGs were identified using a linear models for microarray data package in the R programming language. Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was also performed. Protein-protein interaction (PPI) networks of the DEGs were constructed using the EnrichNet online tool. In addition, cluster analysis of the genes in networks was performed using ClusterONE. A total of 879 DEGs were screened, including 394 upregulated and 485 downregulated genes. Enrichment analysis identified four important KEGG pathways associated with FCHL: One carbon pool by folate, α-linolenic acid metabolism, asthma and the glycosphingolipid biosynthesis-globo series. GO annotation identified 12 enriched biological processes, including one associated with hematopoiesis and four associated with bone cell differentiation. This identification was in accordance with clinical data and experiments into hyperlipidemia and bone lesions. Based on PPI networks, these DEGs had a close association with immune responses, hormone responses and cytokine-cytokine receptors. In conclusion, these DEGs may be used as specific therapeutic molecular targets in the treatment of FCHL. The present findings may provide the basis for understanding the pathogenesis of FCHL in future studies. However, further experiments are required to confirm these results.

Relevance of dietary protein concentration and quality as risk factors for the formation of calcium oxalate stones in cats

The role of dietary protein for the development of feline calcium oxalate (CaOx) uroliths has not been conclusively clarified. The present study evaluated the effects of a varying dietary protein concentration and quality on critical indices for the formation of CaOx uroliths. Three diets with a high protein quality (10–11 % greaves meal/diet) and a varying crude protein (CP) concentration (35, 44 and 57 % in DM) were compared. Additionally, the 57 % CP diet was compared with a fourth diet that had a similar CP concentration (55 % in DM), but a lower protein quality (34 % greaves meal/diet). The Ca and oxalate (Ox) concentrations were similar in all diets. A group of eight cats received the same diet at the same time. Each feeding period was divided into a 21 d adaptation period and a 7 d sampling period to collect urine. There were increases in urinary volume, urinary Ca concentrations, renal Ca and Ox excretion and urinary relative supersaturation (RSS) with CaOx with increasing dietary protein concentrations. Urinary pH ranged between 6·34 and 6·66 among all groups, with no unidirectional effect of dietary protein. Lower renal Ca excretion was observed when feeding the diet with the lower protein quality, however, the underlying mechanism needs further evaluation. In conclusion, although the observed higher urinary volume is beneficial, the increase in urinary Ca concentrations, renal Ca and Ox excretion and urinary RSS CaOx associated with a high-protein diet may be critical for the development of CaOx uroliths in cats.

Dyslipidemia and kidney stone risk

PURPOSE

We studied the impact of dyslipidemia on 24-hour urinalysis and stone composition.

MATERIALS AND METHODS

We retrospectively identified patients with nephrolithiasis who underwent 24-hour urinalysis and lipid profile evaluation within 3 months. Patients were divided into groups based on total cholesterol, high density lipoprotein, nonhigh density lipoprotein and triglycerides. The groups were compared based on demographic data, diabetes, hypertension and each component of 24-hour urinalysis and stone composition. Multivariate analysis and linear regression were performed to control for potential confounders, including age, gender, body mass index, diabetes and hypertension.

RESULTS

A total of 2,442 patients with a mean age of 51.1 years were included in study. On multivariate analysis patients with high total cholesterol had significantly higher urinary potassium and calcium, those with low high density lipoprotein or high triglycerides had significantly higher urinary sodium, oxalate and uric acid with lower pH, and those with high nonhigh density lipoprotein had higher urinary sodium and uric acid. Regarding stone composition, high total cholesterol and triglycerides were significantly associated with a higher uric acid stone rate (p = 0.006 and <0.001, respectively). Linear regression showed a significant association of nonhigh density lipoprotein with higher urinary sodium (p = 0.011) and uric acid (p <0.001) as well as triglycerides and higher uric acid (p = 0.017), and lower urinary pH (p = 0.005).

CONCLUSIONS

There is a link between dyslipidemia and kidney stone risk that is independent of other components of metabolic syndrome such as diabetes and obesity. Specific alterations in the patient lipid profiles may portend unique aberrations in urine physicochemistry and stone risk.

Biomolecular mechanism of urinary stone formation involving osteopontin

Urinary stones consist of two phases-an inorganic (mineral) phase and an organic (matrix) phase. Studies on the organic components of kidney stones have been undertaken later than those on the inorganic components. After osteopontin was identified as one of the matrix components, the biomolecular mechanism of urinary stone formation became clearer. It also triggered the development of new preventive treatments. Osteopontin expression is sporadically observed in normal distal tubular cells and is markedly increased in stone-forming kidneys. Calcium oxalate crystals adhering to renal tubular cells are incorporated into cells by the involvement of osteopontin. Stimulation of crystal-cell adhesion impairs the opening of mitochondrial permeability transition pores (mPTP) in tubular cells and produces oxidative stress, apoptosis, and osteopontin expression. Macrophages phagocytose and digest a small amount of crystals, but many crystals aggregate into a mass containing osteopontin and epithelial cell debris and are excreted into the renal tubular lumen, becoming nuclei of urinary stones. This biomolecular mechanism is similar to atherosclerotic calcification. Based on these findings, new preventive treatments have been developed. Dietary control such as low-cholesterol intake and the ingestion of antioxidative foods and vegetables have successfully reduced the 5-year recurrence rate. Osteopontin antibodies and cyclosporine A, which blocks the opening of mPTP, have markedly inhibited the expression of osteopontin and urinary stone formation in animal models.

Pediatric urolithiasis--does body mass index influence stone presentation and treatment?

PURPOSE

Pediatric obesity is a major public health concern in the United States. We investigated the association of body mass index with presentation and outcome in children with urolithiasis.

MATERIALS AND METHODS

We identified all patients 2 to 18 years old at our institution with a radiographically confirmed first renal or ureteral stone between January 2003 and June 2008. Data abstracted included demographics, stone characteristics, treatment and metabolic evaluation. Patients were stratified into 3 body mass index categories, including lower (10th percentile or less for age), normal (10th to 85th percentile) and upper (85th percentile or greater) percentile body weight.

RESULTS

Of the children 62 boys (55.4%) and 50 girls (44.6%) were evaluable. Mean age at diagnosis was 11.8 years. Body mass index stratification showed lower percentile body weight in 11 patients (9.8%), normal percentile body weight in 55 (49.1%) and upper percentile body weight in 46 (41.1%). Mean stone diameter was 5.0 mm. Of the stones 31 (27.7%) were in the kidney or ureteropelvic junction and 81 (72.3%) were in the ureter. Surgery was done in 87 patients (78.9%) and stone clearance was accomplished by 1 (69.0%) or 2 (31.0%) procedures in all. Lower percentile body weight patients presented earlier than normal and upper percentile body weight patients (9.0 vs 12.2 and 12.0 years, respectively, p = 0.04). Neither stone size nor the number of procedures required for stone clearance differed significantly by body mass index.

CONCLUSIONS

Upper percentile body weight was not associated with earlier stone development, larger stones or the need for multiple surgical procedures. In lower percentile body weight patients symptomatic renal stones developed significantly earlier than in normal or upper percentile body weight patients. Stone size and the surgical intervention rate were similar regardless of body mass index. Further research may identify potential factors predisposing children with lower percentile body weight to early stone development.

Dietary therapy in idiopathic nephrolithiasis

Like other diseases striking predominantly the affluent societies, idiopathic nephrolithiasis is increasing in rich countries and appears to be closely related to dietary habits. In this review we summarize the latest evidence about the efficacy of dietary treatment for idiopathic calcium and uric acid stones, dealing especially with its effect on the urinary stone risk factors, stone recurrences, and clinical limitations. After a short introduction on epidemiology and pathogenesis, we review the role of the most important foods and nutrients in stone formation and protection: water and other fluids, proteins, carbohydrates, fats, salt, milk and dairy products, fruits and vegetables, and vitamins. The final part of the paper will provide practical guidelines for pursuing an anti-lithogenic diet in idiopathic calcium and uric acid stones.

Dietary saturated fat intake is inversely associated with bone density in humans: analysis of NHANES III

Mounting evidence indicates that the amount and type of fat in the diet can have important effects on bone health. Most of this evidence is derived from animal studies. Of the few human studies that have been conducted, relatively small numbers of subjects and/or primarily female subjects were included. The present study assessed the relation of dietary fat to hip bone mineral density (BMD) in men and women using NHANES III data (n = 14,850). Multivariate models using SAS-callable SUDAAN were used to adjust for the sampling scheme. Models were adjusted for age, sex, weight, height, race, total energy and calcium intakes, smoking, and weight-bearing exercise. Data from women were further adjusted for use of hormone replacement therapy. Including dietary protein, vitamin C, and beta-carotene in the model did not influence the outcome. Analysis of covariance was used to generate mean BMD by quintile of total and saturated fat intake for 4 sex/age groups. Saturated fat intake was negatively associated with BMD at several hip sites. The greatest effects were seen among men < 50 y old (linear trend P = 0.004 for the femoral neck). For the femoral neck, adjusted mean BMD was 4.3% less among men with the highest compared with the lowest quintile of saturated fat intake (BMD, 95% CI: highest quintile: 0.922 g/cm2, 0.909-0.935; lowest quintile: 0.963 g/cm2, 95% CI: 0.950-0.976). These data indicate that BMD is negatively associated with saturated fat intake, and that men may be particularly vulnerable to these effects.

Is idiopathic recurrent calcium urolithiasis in males a cellular disease? Laboratory findings in plasma, urine and erythrocytes, emphasizing the absence and presence of stones, oxidative and mineral metabolism: an observational study

BACKGROUND

The site of origin of idiopathic recurrent calcium urolithiasis (IRCU)--a disorder characterized by stones composed of calcium oxalate (CaOx) and/or calcium phosphate (CaPi)--is uncertain, because in urine such risk factors for stones as disturbed Ox, Ca and Pi are not regularly observed.

AIMS

To evaluate whether imbalance of antioxidants and oxidants might be present in IRCU patients that is then followed by abnormal urine, plasma and intracellular mineral homeostasis, and stones.

METHODS

Males were investigated in the laboratory under standardized conditions, and three trials were organized. Trial 1 was cross-sectional, comparing IRCU patients with (n = 111) and without stones in situ (n = 126), focussing on abnormalities of oxypurines and minerals in urine and plasma, and metabolic activity (MA) of the disease. Trial 2 was partly controlled (n = 14 healthy subjects; n = 53 IRCU patients), comparing the plasma levels of total antioxidant status (TAS) and uric acid, the major antioxidant in humans, using the subsets Low (n = 26) and High (n = 27) TAS among IRCU patients in terms of plasma levels of uric acid, ascorbic acid, albumin, alpha-tocopherol and minerals, urinary minerals, CaOx and CaPi (hydroxyapatite) supersaturation. Trial 3, comprising stone-free IRCU patients (n = 8) and healthy controls (n = 8), compared minerals and mineral ratios in plasma and red blood cells (RBCs). Established analytical methodologies were used throughout.

RESULTS

In trial 1, uricemia, hypoxanthinuria and proteinuria were elevated, fractional urinary clearance (FE) of uric acid was decreased in stone-bearing patients, and MA correlated positively with uricemia and urinary total protein excretion. In trial 2, TAS was significantly decreased in IRCU patients vs. healthy controls; low TAS coincided with low plasma uric acid and albumin, unchanged ascorbic acid, alpha-tocopherol and parathyroid hormone, but increased FE-uric acid and Pi excretion; the latter correlated negatively with TAS. In trial 3, plasma minerals were significantly decreased in IRCU patients vs. controls, and Ca/Pi, (Ca/Pi)/Mg and (Ca/Pi)/Na molar ratios increased; the latter ratio was also increased in RBCs, and correlated highly positively with the same ratio in plasma.

CONCLUSIONS

In IRCU 1) renal stones in situ in combination with high fasting uricemia, high hypoxanthinuria and protein-uria, and high MA suggest that a systemic metabolic anomaly underlies stone formation; 2) antioxidant deficit is frequent, unrelated to the presence or absence of stones but apparently related to poor renal uric acid recycling, low uricemia and albuminemia, exaggerated urinary Pi excretion, and low MA; 3) the combination of low plasma TAS, disordered Ca/Pi and other mineral ratios in urine, plasma and RBCs, but unchanged urinary Ca salt supersaturation is compatible with the view that CaPi solid and Ca microlith formation start inside oxidatively damaged cells.

Developments in stone prevention

PURPOSE OF REVIEW

This review focuses on new developments in stone prevention. Unfortunately, no major progress in this field has happened. There is a worldwide lack of randomized and controlled trials, which could confirm our theoretical assumptions and preventive concepts in stone disease. With these preconditions in mind, this review presents the current knowledge of metabolic influences causing the symptom "stone" and the effective measures against it.

RECENT FINDINGS

Modern lifestyle, dietary habits and obesity emerge to be the promoters of idiopathic stone disease. Cross-sectional studies showed significant correlations between these factors and kidney stones with direct implications on our preventive concepts: normalization of body mass index, adequate physical activity, balanced nutrition and sufficient circadian fluid intake. Modern diets containing a lot of animal protein, refined carbohydrates and salt act on the metabolism like an acid load. To overcome these disadvantageous effects, a sufficient supply of potassium and alkali is required. Last but not least, calcium should not be restricted. There is clear evidence from clinical and experimental research that a normal or a high calcium supply is appropriate in calcium stone disease. Only in absorptive hypercalciuria calcium restriction remains beneficial in combination with thiazide and citrate therapy.

SUMMARY

Up to 85% of all stone patients could anticipate lower risk of stone recurrence with elementary reorientation of their lifestyle and dietary habits. Normalizing the major risk factors is easy and cheap. About 15% of patients forming stones require additional specific pharmacological prevention. The specific measures to avoid recurrence of the stone disease are precisely defined.

Effects of dietary fats on bone health in advanced age

Evidence is accumulating that dietary lipids play an important role in bone health. Most of the data supporting the effects of lipids on bones have been collected in young adult and/or developing animals. Based upon this work, mechanisms have been proposed to explain how lipids act to enhance or inhibit bone resorption and deposition. Little work, however, has been done in older models. Since osteoporosis primarily afflicts the elderly, such work is needed in order to determine if mechanisms relevant to the young differ in advanced age, and to develop effective interventions for this especially vulnerable segment of the population. This article reviews evidence that dietary lipids are important to bone health in older individuals, and describes possible mechanisms that may be of particular relevance to the elderly. Specifically, studies supporting the influence of dietary lipids on calcium excretion, growth hormone secretion, fatty acid metabolism, and osteoblast formation are reviewed.