National analysis of urinary cadmium concentration and kidney stone: Evidence from NHANES (2011–2020)

Environmental determinants in the development of kidney stone

The increase with years of kidney stone prevalence has become a serious public health problem worldwide. The geographical distribution pattern of kidney stone (known as "stone belt") clearly indicates the critical role of environmental exposure in its formation, which has long been an underestimated risk factor in studying the development of kidney stone. Based on our previous studies and bibliometric analysis, we discerned four environmental determinants and elaborated their impacts on human internal exposure related to kidney stone formation. The importance of climatic factor lies in that the relatively high temperature and low humidity environment may contribute greater prevalence of kidney stone, since it promotes elevating the concentration of relatively insoluble stone-forming salts. Geological factors including water quality, hydrogeology, and soil environment is involved in kidney stone formation via the food chain. Additionally, air pollution and heavy metal pollutants also act as potential risk factors by directly or indirectly affecting the normal renal function and urinary metabolism. This review thus provides insights into the specific mechanisms affecting metabolic changes in the human body which result in kidney stone formation under environmental exposure, and shed light on the pathogenesis of nephrolithiasis from an interdisciplinary perspective.

Association between exposure to urinary metal and all-cause and cardiovascular mortality in US adults

BACKGROUND

Further evidence is required regarding the influence of metal mixture exposure on mortality. Therefore, we employed diverse statistical models to evaluate the associations between eight urinary metals and the risks of all-cause and cardiovascular mortality.

METHODS

We measured the levels of 8 metals in the urine of adults who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. Based on follow-up data, we determined whether they died and the reasons for their deaths. We estimated the association between urine metal exposure and all-cause mortality using Cox regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models. Additionally, we used a competing risk model to estimate the relationship between metal exposure and cardiovascular mortality.

RESULTS

Among the 14,305 individuals included in our final analysis, there were 2,066 deaths, with 1,429 being cardiovascular-related. Cox regression analysis showed that cobalt (Co) (HR: 1.21; 95% CI: 1.13, 1.30) and antimony (Sb) (HR: 1.26; 95% CI: 1.12, 1.40) were positively associated with all-cause mortality (all P for trend <0.001). In the competing risk model, Co (HR: 1.29; 95% CI: 1.12, 1.48), lead (Pb) (HR: 1.18; 95% CI: 1.03, 1.37), and Sb (HR: 1.44; 95% CI: 1.18, 1.75) were significantly associated with an increased risk of cardiovascular mortality (all P for trend <0.001). Sb, Pb, cadmium (Cd), and molybdenum (Mo) had the highest weight rankings in the final WQS model. All metals showed a complex non-linear relationship with all-cause mortality, with high posterior inclusion probabilities (PIPs) in the final BKMR models.

CONCLUSIONS

Combining all models, it is possible that Sb may have a more stable impact on all-cause and cardiovascular mortality. Meaningful metal effects in individual statistical models still require careful attention.

Urine cadmium and urolithiasis: A systematic review and meta-analysis

Exposure to cadmium may increase risk of urolithiasis, but the results remain inconclusive. This systematic review and meta-analysis aimed to access the association between cadmium exposure and urolithiasis. We searched Medline/PubMed, Embase, Web of Science Core Collection, and Cochrane Central for studies. The primary outcome was the incidence of urolithiasis compared to reference groups. We used relative risk as the summary effect measure. This meta-analysis included eight observational studies and divided into 39 study populations. Among 63,051 subjects, 5018 (7.96%) individuals had urolithiasis. The results indicated that people with an increment of 0.1 μg/g creatinine in urinary cadmium had a 2% increased risk of urolithiasis (pooled relative risk [RR], 1.02; 95% confidence interval [CI], 1.01-1.03) and there is no difference in the risk of urolithiasis in high and low cadmium exposure levels. Meanwhile, people with an increment of 0.1 μg/L in urinary cadmium had a 4% increased risk of urolithiasis (pooled RR, 1.04; 95% CI, 1.02-1.07). Our findings also showed similar associations in both sex, different region (Sweden, China, and Thailand), general and occupational population. The results indicate that cadmium exposure was significantly associated with an elevated risk of urolithiasis. Therefore, it is imperative to take steps to minimize cadmium exposure.