Introduction: Worldwide, the incidence of kidney stones has been progressively increasing. Various factors can influence the risk of stone formation, including lifestyle and eating habits. The dietary investigation is a standard of care in patients with urolithiasis. The objectives of this study were to determine the dietary habits of lithiasis patients in the city of Kinshasa and to investigate the association between dietary habits and the composition of the stones. Material and methods: From January 2017 to September 2019, 85 patients attending 8 hospitals participated in the nutrition survey. Various foods commonly consumed in the Democratic Republic of Congo were categorized based on their composition: foods rich in animal proteins, foods rich in calcium, foods high in sugar, foods high in oxalate, and various vegetables and fruits. We also investigated daily water intake. The composition of the collected stones was analyzed by infrared spectrophotometry. Results: The mean (SD) age of patients was 47.1 (14.0) years, 63.5% of patients were males, 75.3% of the patients had stones located in the upper urinary tract, and 7.1% were undernourished. Most of patients consumed vegetables (77.6%), animal proteins (62.4%), and foods rich in oxalate (58.8%). The daily water intake was less than 1500 mL in more than half of the patients (68.2%). Major anhydrous uric acid stones were associated with a high body mass index (p = 0.025). Male patients with a high oxalate diet had more calcium oxalate stones (64.3%) compared to other types of stones (p = 0.041). Conclusion: High consumptions of vegetables and low water intake were linked to the formation of cal-How to cite this paper:

Background The Democratic Republic of Congo has been a country of intensive mining activities for centuries, but the data on the presence of heavy metals in stones are lacking. This study aimed to identify different heavy metals in urinary tract stones and to investigate their association with the main components of urinary stones. Methods Thirty-six stones from urolithiasis patients (n = 36) followed in 10 hospitals in the Democratic Republic of Congo between January 2016 and September 2019 were analyzed by Fourier transform infrared spectrophotometry. Further analysis using X-ray fluorescence was conducted at the Laboratory of Solids Physics. Results Eight heavy metals were detected in all the stones analyzed. The average (SD) number of heavy metals detected by stone was 5 (1.2). Iron and strontium were detected in all the stones analyzed. Other heavy metals detected included zinc, copper, bromine, rubidium, lead and nickel. Rubidium had the highest concentration in the stones regardless of the sampling site. There was no statistically significant association between the content of heavy metals at the center level and at the crown level of the stones. Rubidium had more affinity with phosphates and purines (p ˂ 0.001). Iron and strontium exhibited a high affinity with weddellite than with whewellite. Conclusion Iron and Strontium were present in all stones analyzed. The presence of heavy metals in stones analyzed might suggest environmental pollution rather than crystalline induction factors.

Introduction metabolic abnormalities are key factors in urolithiasis patients because they can be modified to prevent the risk of urinary stones. The objectives of this study were to estimate the frequency of metabolic abnormalities in the urine of patients with urolithiasis and to determine their possible link with the chemical composition of stones. Methods we conducted a cross-sectional study evaluating 73 patients referred for urolithiasis in 8 clinics in Kinshasa, between January 2017 and September 2019. Twenty four-hour or early morning urine were collected and analyzed in the Tenon Hospital in Paris. Parameters analyzed included pH, specific gravity, creatinine, uric acid, calcium, phosphate, oxalate, citrate and magnesium. Chi square test or chi-square likelihood-ratio and student's t test were used as statistical tests. Results overall, 89% (n=65) of patients with lithiasis had metabolic abnormalities. Mean (SD) age of patients was 47.0 (14.2) years with male to female ratio of 1.6: 1. The mean (SD) 24-hour diuresis was 1836.4 (1216.9) ml; the mean (SD) urine density was 1.018 (0.007); and the mean (SD) pH was 6.1(0.8). Hypocitraturia was the most frequently observed metabolic abnormality and was found in 76.7% patients. Other significant metabolic abnormalities were low magnesuria (35.6%), hyperoxaluria (11%), and low sulphaturia (74%). Whewellite (73.5%) was the main chemical component. The mean pH was higher in patients with carbapatite and struvite stones (p=0.031). Conclusion this study suggests that inadequate diuresis and hypocitraturia were important lithogenic factors. The population should be encouraged to increase water intake to limit the frequency of urine super saturation with crystals.

Background Urolithiasis is increasingly diagnosed worldwide. Stone analysis is an important part in the assessment of patients with urolithiasis. However, in sub-Saharan Africa, data on the composition of urinary stones are limited. This study aimed to describe the composition and sites of urinary stones and to investigate relationship between socio-demographic characteristics, clinical profile of patients, and the composition of urinary stones. Methods A retrospective analysis of 132 patients with urolithiasis who visited one of the seven hospitals in the Democratic Republic of Congo during eight years of study period (January 2010 to January 2018) was conducted. Stones were analyzed by infrared spectrophotometry. Results Most of stones analyzed (n = 82, 62.1%) originated from the upper urinary tract with a difference across gender (58.5% males vs. 41.5% females, p = 0.001). Only three stones (two from whewellite and one from anhydrous uric acid) were considered pure (2.3%), excluding the protein frame (less than 5%). Whewellite, proteins, and carbapatite were identified in 97.7%, 96.2%, and 80.3% of the stones analyzed, respectively; and in 91.7%, 89.4%, and 67.7% of the nuclei of the stones analyzed, respectively. Taking into account the proportion of each constituent in the stones analyzed, whewellite (68.9%), anhydrous uric acid (10.6%), and carbapatite (8.3%) were the main constituents in respectively 68, 9%, 10.6%, and 8.3% of the stones analyzed. Conclusion Whewellite, anhydrous uric acid, and carbapatite represented the most frequent main components of stones identified, suggesting that dietary hyperoxaluria could be an important factor in lithogenesis in the Democratic Republic of Congo.