Prevalence of Environmental Acquired Cadmium Nephropathy among smokers

Abstract

Cadmium has beenrecognized as an occupational health hazard for many decades. In the general population in the absence of specific industrial exposure, the main sources of exposure being food and tobacco smoke. During the last decade an increasing number of studies have found adverse health effects at much lower levels than in the earlier studies(Järup and Akesson, 2009).

Cigarette smoke contains substantial amounts of Cd. Average Cd levels in cigarettes range from 1000 to 3000 μ g/kg. One pack of cigarettes deposits 2–4 μg into the lungs of a smoker while some of the smoke passes into the air to be inhaled by smokers and nonsmokers alike(Ashraf , 2012).

Cadmium nephropathy is characterized by low molecular weight (LMW) proteinuria due to diminished intrarenal uptake and catabolism of filtered proteins. In Cadmium nephropathy, proximal tubular dysfunction persists until renal failure supervenes(Järup and Akesson , 2009). Aim of this Study was to assess the risk for increased cadmium exposure among smokers and to detect the risk for development of cadmium induced nephropathy among smokers.

This study was done on 90 men subjects who were classified into 60 current men smokers working in Ain Shams university hospitals either manual workers, clerks or medical staff and 30 apparently healthy male non smokers volunteers as a control group matched by age and working status.

Participants were divided into two groups: Group (1): 60 current men smokers. They were subdivided into 2 equal subgroups: • Subgroup 1a: 30 mensmokers for ≥10 years. • Subgroup 1b:30men smokers for <10 years. Group (2) (Non smokers): 30 healthymen non smokers working in Ain Shamsuniversity hospital. All participants were subjected to the following: • Medical history including symptoms suggestive of cadmium toxicity like bony aches. • Smoking Assessment by py index. • General examination. • Laboratory studies included serum creatinine, urea, complete urine analysis, urinary protein creatinine ratio, urinary beta 2 microglobulin and urinary cadmium levels. • Estimation of creatinine clearance (CrCl) by Cockcroft–Gault formula. • Renal biopsy if protein/creatinine ratio is more than 1 to exclude the presence of primary renal disease. In the current study, the participants in both groups were matched as regard age ,occupation and body weight.

Urinary cadmium in this study was significantly higher among smokers when compared to non smokers and there was a statistically significant correlation between urinary cadmium and pack/year index and smoking duration. As regard beta 2 microglobulin,there was a statistically positive correlation between urinary beta 2 microglobulin and urinary cadmium level and smokers had a higher beta 2 microglobulin level compared to non smokers with no statistically significant difference between them. No statistically significant difference between the studied groups as regard serum creatinine ,blood urea and protein/creatinine ratio.

There was a statistically significant negative correlation between eCrCl and urinary cadmium level in spite ofthe non significant difference between the smokers and non smokers as regard eCrCl.

Among non smokers, urinary cadmium level had a statistically significant positive correlation versusbeta 2 microglobulin. On the other hand there was inverse significant correlation between urinary cadmium versus creatinine clearance and there was no statistically significant correlation between urinary cadmium versus other variables(serum creatinine,blood urea,urine protein/cr ratio,age,body weight,SBP and DBP). Among smokers, the urinary cadmium level had a statistically significant positive correlation with B2 microglobulin,age and pack/year index. On the other hand there was inverse significant correlation between urinary cadmium and creatinine clearance.There is no statistically significant difference between urinary cadmium versus other variables.

As regard symptoms of cadmium exposure like (bony aches), those with bony ache had higher urinary cadmium levelthan those without bony achewith significant difference between both groups. As regard urinary B2-microglobulin level in participants with and without bony aches there was no significant difference between both groups.

In this study, there was no significant correlation between urinary cadmium and neither systolic nor diastolic blood pressure.On the other hand, smokers more than 10 years had a statistically significant higher diastolic blood pressure compared to non smokers.