Abstract
Objective: The purpose of this study was to examine a relationship between smoking and urine pH, a new predictor of chronic kidney disease, and to assess whether smoking and/or drinking are associated with renal dysfunction determined by glomerular filtration rate (eGFR).
Methods: The study was conducted on 78 male current smokers and 79 male life-time non-smokers aged 50-69 years, who underwent a health check-up. The classification of metabolic syndrome (MetS) was applied to subjects whose waist circumference was larger than 85 cm and had at least 1 of 4 metabolic syndrome criteria (MetS+1).
Results: Smokers had a lower urine pH and higher plasma uric acid levels compared with non-smokers after adjustment for drinking and MetS+1. In smokers, there were strong correlations between amount of drinking and urine pH, and drinking and uric acid. In the smoker group, those whose urine pH was less than 6.0 had a significantly lower eGFR compared to those whose urine pH was 6.0 or greater, but there was no difference in MetS factors. The combination of smoking and drinking, especially heavy drinking, was associated with lower urine pH and lower eGFR. The presence of smoking, drinking and MetS+1 together was associated with the lowest urine pH, highest uric acid, and lowest eGFR.
Conclusion: The combined presence of smoking and drinking, especially heavy drinking, was associated with a lower urine pH independently of presence of MetS+1 and was associated with a lower eGFR. These results suggest that smoking is an important contributor to a low urine pH, which in turn may lead to renal dysfunction.
