Sociodemographic features, serum urea, creatinine and blood urea nitrogen/creatinine ratio in chronic kidney disease patients – A record based retrospective study

INTRODUCTION

Chronic kidney disease (CKD) is a progressive reduction in renal function. It is a condition where the kidneys lose their normal function, especially excretory and regulatory functions which can be due to infections, autoimmune diseases, diabetes, hypertension, cancer, and toxic chemicals. CKD is heading toward becoming a major health problem and is rapidly assuming epidemic proportions globally.^[1-4]

Biochemical markers play an important role in accurate diagnosis and assessing risk and adopting therapy to improve clinical outcomes. Instead of urine analysis which is relatively discomforting for patients, serum analysis of renal function markers such as urea, creatinine, uric acid, and electrolytes is used routinely. Blood tests for blood urea nitrogen (BUN) which is a major nitrogenous end product of protein and amino acid catabolism and creatinine which is a breakdown product of creatine phosphate in muscle are excreted by kidneys. BUN is an indirect and rough measurement of renal function that measures the amount of urea nitrogen in blood and is directly related to the excretory function of the kidney. Creatinine tests diagnose impaired renal function and measure the amount of creatinine phosphate in blood. Urea and creatinine are good indicators of a normal functioning kidney and an increase in the serum is indications of kidney dysfunction. BUN and serum creatinine are widely accepted and the most common parameters to assess renal functions. Collection of blood for serum analysis is an invasive technique and thus causes anxiety and discomfort to patients due to blood loss from frequent blood sampling and thereby potentially increasing the risk for patients as well as health-care professionals to blood–borne diseases. Hence, a simple diagnostic test that provides a reliable evaluation of disease status and stages and is of value to both clinicians and patients is required. Serum urea and creatinine are the most widely accepted parameters to assess CKD status as well as to assess renal status. According to standard norms of the urea value is 13–43 mg/dL, the creatinine value is 0.9–1.3 mg/dL for men and 0.6–1.1 mg/dL for women, urea nitrogen in the blood is 5–20 mg/dL, and BUN-creatinine ratio (BCR) is 10–20.^[5-7]

Categories of CKD: CKD may result from disease processes in any of the three categories: Pre-renal (decreased renal perfusion pressure), intrinsic renal (pathology of the vessels, glomeruli, or tubules-interstitium), or post-renal (obstructive).^[8] Hence, the present study was done to assess the serum urea, creatinine levels, and BCR in CKD subjects.

MATERIAL AND METHODS

RESULTS

Table 1 describes the sociodemographic features of 57 CKD patients, and it was found that the number of male patients was 24 (75.4%) and the number of female patients was 14 (24.6%). The number of patients belonging to the age group category of 25–50 years were 5 (8.7%) and from 50 to 75 were 42 in number (73.6%) and above 75 years were 10 in number (17.5%).

Tables 2 and 3 show the renal parameters in CKD patients. Out of 57 patients, 17 (29.8%) had normal serum urea levels in that 14 (24.6%) were males and 3 (5.3%) were females. Moreover, 40 had abnormal serum urea levels in that 29 (50.9%) were males and 11 (19.3%) were female. 54 patients (94.7%) had abnormal values, based on creatinine levels, in that, 40 (70.2%) were males and 14 (24.6%) females were affected. BCR was categorized into prerenal cause, normal, and post-renal cause of kidney disease [Figure 1]. In prerenal, out of 26 patients, 20 (35.1%) were males and 6 (10.5%) were females. The remaining patients come under the normal category since all CKD patients underwent treatment such as dialysis.

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Figure 1:

Categorization of blood urea nitrogen (BUN)-creatinine ratio.

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DISCUSSION

In our study, we found that out of 57 patients, 3/4^th were males and 1/4^th were females. In the age group category, the 50–75 age group was more commonly affected than the other categories of age. In CKD patients, the serum creatinine level was found to be predominately abnormal compared to serum urea level and BCR.

In a study done by Goldberg and Krause regarding the influence of gender on CKD, the prevalence of CKD tends to be higher in women than in males, but in our study, the prevalence of CKD tends to be higher in males.^[9]

In 2006, a study was conducted on the progression of CKD based on age and gender and found that the 70–79 age group was more commonly affected when compared to the age <69 and age more than 79.^[10] In our study, it was found that the age group of 50–75 was more commonly affected than the age group <25 and more than 75 years.

In 2016, a study was conducted on the assessment and correlation of urea and creatinine levels in saliva and serum of patients with CKD, diabetes, and hypertension. It was concluded that serum and salivary urea and creatine are elevated and there is a strong positive relationship with P = 0.000 (<0.001).^[11] In our study, we found that there was also a significant increase in serum urea and creatinine levels.

The study done on BCR in acute kidney injury patients shows similar results to our study. Multivariate logistic regression analysis for hospital mortality showed that the odds ratio (5.73) of high BCR (BCR >20) was higher than that of low BCR (3.32).^[1]

CONCLUSION

The present study found that male gender and age group 50– 75 years were most commonly affected with CKD. The serum creatinine level was found to be predominately abnormal compared to the serum urea level and BCR.