Retrospective analysis of urinary tract stone composition in a Chinese ethnic minority colony based on Fourier transform infrared spectroscopy

To analyze the relationship between the composition of urinary stones and various influencing factors in the Enshi region. We used FT-IR to examine the composition of 1092 stone samples. Combined with the relevant clinical materials, the data were analyzed using both one-dimensional statistical methods and multivariate statistical methods. The study included 1092 stone samples, classified as follows: 457 (41.8%) with a single component, 453 (41.5%) with two components, 149 (13.6%) with three components, and 33 (3.0%) with four components. Stones were categorized into five types: Calcium Oxalate (CaOx) (76.4%), carbapatite (CaP) (9.3%), Struvite (ST) (8.3%), Uric Acid (UA) (4.9%), and Others (1.0%). Age, gender, urinary tract infection (UTI), family history of urinary stones (FH), hyperuricemia (HUA) and stone location were significantly associated with stone type. Logistic regression revealed that females and UTI were relative risk factors for predicting CaP and ST, while FH and HUA were relative risk factors for predicting UA. Our study indicates that the overall composition of urinary tract stones in the Enshi region is consistent with that of the entire China. Additionally, the predisposing factors for stone formation vary in terms of gender, age, FH, UTI, hyperuricemia HUA, and stone location.

Characteristics and Types of Urolithiasis in the Eastern Region of Saudi Arabia: A Single-Center Retrospective Study

Introduction

Urolithiasis is one of the most common conditions encountered in clinical practice with the prevalence increasing globally in the last few decades. Urolithiasis has been found to be more common in areas with a hot climate, such as Saudi Arabia. The aim of this study was to determine the characteristics and the types of urolithiasis most frequently found in the Eastern Region of Saudi Arabia.

Methods

This was a single-center retrospective cohort study based on data extracted from an electronic hospital information system (BESTCare) of all patients diagnosed with urolithiasis at King Abdulaziz Hospital, a tertiary care center in Saudi Arabia's Eastern Region. From January 2013 to December 2016, all adult patients aged 18 and up who presented with urinary calculi (renal and ureter) were included in the study.

Results

A total of 235 patients were reviewed, with a mean age of 48.52 years. Renal calculi were more prevalent in males (74.5%). Calcium oxalate was the predominant type (76%), followed by uric acid calculi (18%) and cystine calculi (4.8%). A small proportion (1.2%) was calcium phosphate calculi. The most frequently associated comorbidity was hypertension (17.9%). The majority (78.5%) had a stone removal through a ureteroscopy and 8.2% by percutaneous nephrolithotomy (PCNL). The mean stone size was 12.2 ± 9.91 mm, with a mean stone Hounsfield unit (HU) of 789.9. The mean urinary PH at stone incident was 6.77, and the mean creatinine level was 92.4mmol.

Conclusion

This study showed that males were more affected by urolithiasis, compared to females in the Eastern Region. Furthermore, calcium oxalate was the predominant type. These findings are consistent with the literature and they highlighted the necessity for further studies in this area, to provide insight into the pathophysiology and incidence of renal calculi for improving patient care.

Obesity rates in renal stone formers from various countries

OBJECTIVE

To collect evidence on the rate of obesity in renal stone formers (RSFs) living in different climatic areas and consuming different diets.

MATERIALS AND METHODS

Data of adult renal stone formers were retrospectively collected by members of U-merge from 13 participant centers in Argentina, Brazil, Bulgaria (2), China, India, Iraq (2), Italy (2), Nigeria, Pakistan and Poland. The following data were collected: age, gender, weight, height, stone analysis and procedure of stone removal.

RESULTS

In total, 1689 renal stone formers (1032 males, 657 females) from 10 countries were considered. Average age was 48 (±14) years, male to female ratio was 1.57 (M/F 1032/657), the average body mass index (BMI) was 26.5 (±4.8) kg/m2. The obesity rates of RSFs in different countries were significantly different from each other. The highest rates were observed in Pakistan (50%), Iraq (32%), and Brazil (32%), while the lowest rates were observed in China (2%), Nigeria (3%) and Italy (10%). Intermediate rates were observed in Argentina (17%), Bulgaria (17%), India (15%) and Poland (22%). The age-adjusted obesity rate of RSFs was higher than the age-adjusted obesity rate in the general population in Brazil, India, and Pakistan, whereas it was lower in Argentina, Bulgaria, China, Italy, and Nigeria, and similar in Iraq and Poland.

CONCLUSIONS

The age-adjusted obesity rate of RSFs was not higher than the age-adjusted obesity rate of the general population in most countries. The relationship between obesity and the risk of kidney stone formation should be reconsidered by further studies carried out in different populations.

Scanning electron microscopy in analysis of urinary stones

Urolithiasis is a frequent and in many cases serious disease. Proper analysis of kidney stone composition is crucial for appropriate treatment and prevention of disease recurrence. In this work, scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy was applied for a study of 30 samples covering the most common types of human kidney stones. The results are analyzed and evaluated in terms of applicability of the method for both routine kidney stone analysis as well as collecting of specific data. The method provides complex information about studied samples including morphology of the stones and of the present crystals or their aggregates. It also brings information on elemental composition of the phases. After application of standardization, quantitative microanalysis with detection limits of 400 ppm (Mg, P, S, Cl, K, Ca), 500 ppm (Na) and 1200 ppm (F) was obtained. Compositional mapping with EDS shows the elemental distribution within a sample. This study demonstrated that information on morphology and chemistry acquired by these methods was highly reliable for identification of phases, even when present in small amounts. It provided information on kidney stone structure, relationships between phases, major and minor element content, and variations in chemical composition related to the growth of the stones. SEM represents a powerful tool in urinary stone analysis, since a single facility can produce a wide spectrum of information. It can be suggested as a basic method used for routine urinary stone identification, whilst bringing additional detailed information that cannot be obtained by other methods.

Fluoride potentiates tubulointerstitial nephropathy caused by unilateral ureteral obstruction

The contamination of ground water by fluoride has been reported worldwide. Most fluoride (approximately 70%) is filtered by the kidneys; humans or experimental animals with renal damage therefore may be more affected by fluoride exposure than those with normal kidney function. Tubulointerstitial fibrosis, which involves macrophage-promoted extracellular matrix production and myofibroblast migration, can be induced in rats by unilateral ureteral obstruction (UUO). We examined the effects of fluoride exposure on tubulointerstitial fibrosis in the obstructed kidney of UUO rats. The left ureters of 6-week-old male rats were ligated using silk sutures. Fluoride was then administered for 2 weeks at doses of 0, 75, and 150ppm in the drinking water. Real-time polymerase chain reaction was performed to analyze transforming growth factor beta 1 (TGF-β₁) transcription; histological and immunohistochemical staining were used to identify positive areas within the renal cortex and staining-positive cells by image analysis. Significant increases were observed in the obstructed kidneys of UUO rats exposed to 150ppm fluoride (compared to 0ppm) for areas or number of cells that stained with Masson trichrome or with antibodies against collagen type I, alpha-smooth muscle actin (α-SMA, a myofibroblast marker), ED1, ED2, and ED3 (macrophage markers), and TGF-β₁. Taken together, these observations suggested that fluoride exacerbates tuburointerstitial nephropathy resulting from UUO, and that this effect occurs via activation of the M2 macrophage-TGF-β1-fibroblast/myofibroblast-collagen synthesis pathway.

Prevalence of renal uric acid stones in the adult

The aim of this study was to estimate uric acid renal stone prevalence rates of adults in different countries of the world. PubMed was searched for papers dealing with "urinary calculi and prevalence or composition" for the period from January 1996 to June 2016. Alternative searches were made to collect further information on specific topics. The prevalence rate of uric acid stones was computed by the general renal stone prevalence rate and the frequency of uric acid stones in each country. After the initial search, 2180 papers were extracted. Out of them, 79 papers were selected after the reading of the titles and of the abstracts. For ten countries, papers relating to both the renal stone prevalence in the general population and the frequency of uric stones were available. Additional search produced 13 papers that completed information on 11 more countries in 5 continents. Estimated prevalence rate of uric acid stones was >0.75% in Thailand, Pakistan, Saudi Arabia, Iran, South Africa (white population), United States and Australia; ranged 0.50-0.75% in Turkey, Israel, Italy, India (Southern), Spain, Taiwan, Germany, Brazil; and <0.50% in Tunisia, China, Korea, Japan, Caribe, South Africa (blacks), India (Northern). Climate and diet are major determinants of uric acid stone formation. A hot and dry climate increases fluid losses reducing urinary volume and urinary pH. A diet rich in meat protein causes low urinary pH and increased uric acid excretion. On the other hand, uric acid stone formation is frequently associated with obesity, metabolic syndrome and diabetes type 2 that are linked to dietary energy excess mainly from carbohydrate and saturated fat and also present with low urine pH values. An epidemic of uric acid stone formation could be if current nutritional trends will be maintained both in developed countries and in developing countries and the areas of greater climatic risk for the formation of uric acid stones will enlarge as result of the "global warming".

Advances in CT imaging for urolithiasis

Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT) is highly sensitive (>95%) and specific (>96%) in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT) and technological innovations in CT such as dual-energy CT (DECT) has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice.

Renal function in patients with urinary stones of varying compositions

Kidney stones are a potential risk factor for chronic kidney disease. The impact of different urinary stone components on renal function is unknown. In this study, we retrospectively reviewed 1,918 medical records of patients with urolithiasis. The renal function was evaluated as estimated glomerular filtration rate. All the stones were analyzed by Fourier transform infrared spectroscopy. The patients were divided into five groups according to the stone components. Statistical analysis was performed with analysis of variance. All the patients with stones had Stage 2-3 chronic kidney disease. The patients with uric acid and struvite stones had significantly lower estimated glomerular filtration rate compared with those having other stone components (p<0.01). Furthermore, the patients with calcium-containing stones (calcium oxalate and calcium phosphate) had significantly better renal function than those with non-calcium-containing stones (struvite and uric acid, p<0.01). Patients with urolithiasis had decreased renal function, and the impact of renal function varied depending on the stone components. We conclude that stone analysis is important in predicting the change in renal function in patients with urolithiasis. Moreover, the patients with non-calcium-containing stones, such as struvite and uric acid stones, should be carefully evaluated and treated to preserve their renal function.