Renal Dysfunction Indicators in Lead Exposed Workers

Blood Lead Level and Renal Impairment among Adults: A Meta-Analysis

Background: The adult population in lead-related occupations or environmentally exposed to lead may be at risk for renal impairment and lead nephropathy. This meta-analysis aims to determine the impact of blood lead level (BLL) on renal function among middle-aged participants. Methods: Cross-sectional, longitudinal, or cohort studies that reported BLL and renal function tests among adult participants were retrieved from PubMed, Scopus, and ISI Web of Science. Relevant studies were included and assessed for quality using the Newcastle-Ottawa Scale (NOS). The pooled mean BLL of participants with a high BLL (≥30 µg/dL), moderate BLL (20-30 µg/dL), and low BLL (<20 µg/dL) was estimated using the random effects model. The pooled mean differences in BLL, blood urea nitrogen (BUN), creatinine, uric acid, and creatinine clearance between the exposed and non-exposed participants were estimated using the random effects model. Meta-regression was performed to demonstrate the association between the effect size (ES) of the pooled mean BLL and renal function. Heterogeneity among the included studies was assessed using the Cochrane Q and I2 statistics. Cochrane Q with a p value less than 0.05 and I2 more than 50% demonstrated substantial heterogeneity among the studies included. Publication bias was assessed using the funnel plot between the effect size and standard error of the effect size. Results: Out of 1657 articles, 43 were included in the meta-analysis. The meta-analysis demonstrated that the pooled mean BLL in the participants with a high BLL, moderate BLL, and low BLL was 42.41 µg/dL (95% confidence interval (CI): 42.14-42.67, I2: 99.1%), 22.18 µg/dL (95% CI: 21.68-22.68, I2: 60.4%), and 2.9 µg/dL (95% CI: 2.9-2.9, I2: 100%), respectively. The mean BLL of the exposed participants was higher than that of the non-exposed participants (weighted mean difference (WMD): 25.5, p < 0.0001, 95% CI: 18.59-32.45, I2: 99.8%, 17 studies). The mean BUN (WMD: 1.66, p < 0.0001, 95% CI: 0.76-2.55, I2: 76%, 10 studies) and mean creatinine (WMD: 0.05, p = 0.007, 95% CI: 0.01-0.08, I2: 76.8%, 15 studies) in the exposed participants were higher than those in the non-exposed participants. The mean creatinine clearance in the exposed participants was lower than that in the non-exposed participants (standard mean difference (SMD): -0.544, p = 0.03, 95% CI: -1.035-(-0.054), I2: 96.2%). The meta-regression demonstrated a significant positive effect of BLL on BUN (p = 0.022, coefficient: 0.75, constant: -3.7, 10 studies). Conclusions: BLL was observed to be associated with abnormal renal function test parameters, including high BUN, high creatinine, and low creatinine clearance. Moreover, BUN seemed to be the most valuable prognostic marker for lead-induced renal impairment. Therefore, regular checks for renal function among lead-exposed workers should be a priority and publicly promoted.

Lead Nephropathy: Revisiting an Overlooked Cause of Kidney Disease

Despite the recognition of lead nephropathy as a consequence of environmental and occupational lead exposure, lead nephropathy still appears to be underrecognized by physicians as a cause and promoter of chronic kidney disease (CKD), especially in people with more apparent causative factors such as diabetes and hypertension. This review focuses on the clinical, pathophysiological and epidemiological perspectives of lead nephropathy with the objective of promoting the awareness of this important but overlooked cause of CKD among physicians. Literature was reviewed using available medical journals and online literature search through Google, Pubmed, Medline, Medscape and HINARI databases. The key words employed were: Lead Nephropathy, Environmental and Occupational lead exposure and chronic kidney disease. Lead nephropathy which is a tubulointerstitial nephritis, may present acutely or chronically in association with hypertension. The clinical diagnosis of lead nephropathy is complex, because the symptoms are varied and non-specific especially with subclinical nephrotoxicity. The recognition of lead nephropathy can be enhanced if physicians have a high index of suspicion in the assessment of patients with renal disease. It is recommended that the evaluation of environmental and occupational nephrotoxins like lead be incorporated into programs for the prevention of CKD, especially in developing countries where lead exposure and toxicity still remain largely unchecked and the prevalence and burden of CKD is increasing.

Lead-related nephrotoxicity: a review of the epidemiologic evidence

Chronic kidney disease (CKD) represents a major global public health concern. Efforts to prevent and/or slow progression of CKD are essential. Lead nephropathy, characterized by chronic tubulointerstitial nephritis, is a well-known risk of chronic, high-level lead exposure. However, in recent years, lead exposure has declined sharply, particularly in developed countries. We reviewed epidemiologic research in general, occupational, and patient populations to assess whether lead, at current exposure levels, still contributes to nephrotoxicity. Other pertinent topics, such as risk in children, genetic susceptibility, and co-exposure to cadmium, are also considered. The data reviewed indicate that lead contributes to nephrotoxicity, even at blood lead levels below 5 microg/dl. This is particularly true in susceptible populations, such as those with hypertension (HTN), diabetes, and/or CKD. Low socioeconomic status is a risk factor for both lead exposure and diseases that increase susceptibility. Future public health risk for lead-related nephrotoxicity may be most significant in those rapidly developing countries where risk factors for CKD, including obesity and secondary HTN and diabetes mellitus, are increasing more rapidly than lead exposure is declining. Global efforts to reduce lead exposure remain important. Research is also needed to determine whether specific therapies, such as chelation, are beneficial in susceptible populations.

Lead blood concentrations and renal function evaluation: study in an exposed Mexican population

The relation of blood Pb concentrations and renal dysfunction has been reported in association with interstitial fibrosis, tubular atrophy, and decreased glomerular filtration. In this report information about blood Pb concentrations and renal function tests in a population from Oaxaca, Mexico is analyzed. The main changes found were that males had higher blood Pb concentrations than females (P<0.0012); the leading variables associated with this were occupation (glazed pottery workers, P=0.0001) and the use of glazed pottery for preparing meals (P=0.0000). Variables that better explain uric acid variability were blood Pb concentrations, sex, weight, and height (r2=0.23). Hyperuricemia was associated with blood Pb concentrations above 40 microg/dL (OR=1.74, 95% CI, 1.12-2.61). SCr was associated with sex, age, and blood Pb, with coefficient r2=0.12. Our findings might be related to inadequate control of oven emissions, a situation that will require further analysis and the implementation of preventive measurements for the nonoccupational exposed population.