Estimation of serum creatinine, serum urea, glomerular ltration rate and proteinuria among apparently healthy adults to assess the renal impairment and its association with body mass index: An observational hospital-based study

Estimation of serum creatinine, serum urea, glomerular ltration rate and proteinuria among apparently healthy adults to assess the renal impairment and its association with body mass index: An observational hospital-based study Singh Ray A.1, Kumar Kare P.2*, Makwane H.3, Saxena T.4, Garg C.5 DOI: https://doi.org/10.17511/ijmrr.2020.i02.09 1 Amit Singh Ray, Associate Professor, Department of Medical Biochemistry, Gandhi Medical College, Bhopal, Madhya Pradesh, India. 2* Pawan Kumar Kare, Demonstrator, Department of Medical Biochemistry, Gandhi Medical College, Bhopal, Madhya Pradesh, India. 3 Haresingh Makwane, Assistant Professor, Department of Medical Biochemistry, Gandhi Medical College, Bhopal, Madhya Pradesh, India. 4 Tripti Saxena, Professor, Department of Medical Biochemistry, Gandhi Medical College, Bhopal, Madhya Pradesh, India. 5 Chitransh Garg, MBBS Student, Department of Medical Biochemistry, Gandhi Medical College, Bhopal, Madhya Pradesh, India.


Introduction
Obesity is a major growing health concern in India due to its increasing prevalence found in younger and adult populations [1]. The most common causes for obesity are excessive food intake, lack of physical activities and genetic susceptibility [2] which makes this population more vulnerable to the adverse effects of obesity like; diabetes mellitus in urine is also a recommended best predictor parameter for the assessment of renal function at the early stage [10].
The effect of obesity on renal function in obese adults has not been adequately described. In many epidemiologic studies, body mass index (BMI) is used as a good measurement of obesity [11,12].
According to Asian revised guidelines, Asian Indians are categorized on the basis of BMI in overweight if BMI between 23.0 to 24.9 kg/m2) [13] and obesity if BMI ≥25 kg/m2 [14]. Therefore, the present study is designed to assess the renal function parameters in normal, overweight, and obese subjects as Categorized on the basis of BMI to find out the association of renal parameters with obesity.

Results
The present study was conducted in 100 study subjects which included 48 males and 52 females.
The study group was further divided on the basis of BMI into normal, overweight, and obese study groups as given in [Table 1] with the maximum number of subjects are falling into obese subgroups (34%). Table 1 also shows more number of females as compared to males in both overweight (20 females and 13 males) and obese groups (18 females and 16 males).     Table 2 shows the values of all the anthropometric parameters and the laboratory investigations carried out in normal, overweight, and obese study groups.
There was a significant difference in the BMI of all the study groups. Serum urea and creatinine levels in obese individuals were significantly raised as compared to normal subjects although they were in the normal ranges. The eGFR (MDRD) was also significantly raised in both overweight as well as obese groups as compared to the normal study group.
There was a statistically significant correlation found between BMI and renal function parameters such as urea, creatinine, and estimated glomerular filtration rate as shown in Table 3.
In Table4, among study subjects, total 4.0% subjects had high blood urea and 5.0% had >1.2 mg/dl creatinine. The prevalence of low eGFR was found 3.0% out of that 2.0% prevalence was found in the obese group. A total of 2.0% prevalence of proteinuria observed among subjects and especially in obese subjects.

Discussion
Chronic kidney disease is a common and increasing public health problem worldwide [17,18]. This is the first hospital-based study to estimate renal impairment in Central Indian adults with obesity. In the present study, the prevalence of obesity (BMI ≥25 kg/m2) among Central Indian adults was 34%.
In the North Indian population, Sigh NP et al have reported 26.8% of the prevalence of obesity [19] which was lower in comparison to the present study result.
Also, the prevalence of CKD in the present study subjects was found at 3.0%. The current study is aware of some studies which reported the prevalence of CKD in India. These studies reported CKD prevalence of 0.79% [20] and 1.39% [21].
However, these studies had some limitations. The variation in the prevalence rate in different settings may be due to different criteria for the assessment of CKD, age, gender, and urban or rural settings.
In support of our result, Singh NP et al have reported 4.2 % CKD prevalence by considering low eGFR criteria which were estimated by MDRD formula [19]. Creatinine is the anhydrous form of creatine that is present in muscles. Creatinine is Filtered by the glomerulus and thus, serum creatinine estimation is considered as an indirect measure of glomerular filtration. Diminishing of GFR results in the rise of serum creatinine and urea levels [22].
In the present study, obese subjects were showed significantly higher levels of urea and creatinine as compared to normal healthy subjects group.
Progressively rose in urea and creatinine with increasing BMI indicating increase renal perfusion and hyper-filtration in study subjects [23]. The interesting finding of the present study was that levels of creatinine increased proportionally to the levels of urea. In support of our findings, other studies were also reported a similar trend [24,25].  [19,20,29] and our result also in a similar trend.

Limitations
A major limitation of this study is the small sample size. Another limitation of this study is that the current study did not use isotope dilution mass spectrometry (IDMS) traceable creatinine method. W/H ratio is also an alternative anthropometric index of obesity however, it was not calculated in this study.

Conclusion
Obesity is a major growing health concern in India due to its increasing prevalence found in the younger adult population. Our results confirmed that increasing BMI has a significant association with renal function parameters and should be considered to determine the early changes in renal function and renal glomerular injury with an increase in body weight. Keeping a healthy rage BMI may contribute to the prevention of renal impairment.

What does this study add to the existing knowledge
Early-stage detection of renal function tests in obese subjects reduces the risk of renal problems.
Obesity is one of the important factors to increase renal impairment in normal healthy subjects.