Age- and sex-specific reference intervals for blood urea nitrogen in Chinese general population

Qingquan Liu,Zhi Chen,Yongman Lv,Yiru Wang,Xiaolin Guo

doi:10.1038/s41598-021-89565-x

Qingquan Liu, Zhi Chen + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-89565-x

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Abstract

Blood urea nitrogen (BUN) is a nitrogenous end product of protein metabolism. This study aims to explore the age- and sex-specific distribution of BUN among healthy Chinese adults. A total of 24,006 BUN values from healthy adults (14,148 males and 9858 females) were included in the cross-sectional study. Males had a higher median BUN value compared to females (4.6 mmol/L vs. 4.1 mmol/L). BUN values showed a positive correlation with body mass index (BMI), cholesterol, and blood sugar (P < 0.0001). However, eGFR showed a negative correlation with the BUN reference value (P < 0.0001) in both sexes. Multiple linear regression analysis confirmed that the positive associations of BUN levels and age were statistically significant after adjusting confounding factors (P < 0.001). Thus, the serum BUN values increased by 0.21 mmol/L for males and 0.282 mmol/L for females per 10 years. The BUN values corresponding to the 1st, 2.5th, 50th, 97.5th, and 99th percentiles for any specific age in both sex were also calculated. These results indicate that the serum BUN reference value is significantly affected by age and gender, and thus, its interpretation is age- and sex-dependent.

Highlights

Blood urea nitrogen (BUN) is a nitrogenous end product of protein metabolism
Multiple linear regression analysis confirmed that the positive associations of BUN levels and age were statistically significant after adjusting confounding factors in males (β = 0.21, 95% confidence interval, CI 0.187–0.233, P < 0.001), and females population (β = 0.282, 95% CI 0.255–0.309, P < 0.001)
The increase in the rate of serum BUN values was 0.21 mmol/L and 0.282 mmol/L per 10 years, respectively. These results indicated that BUN levels of both sex groups increased steadily with age, adjusted for body mass index (BMI) and estimated glomerular filtration rate (eGFR), albumin, and triglyceride

Summary

Introduction

Blood urea nitrogen (BUN) is a nitrogenous end product of protein metabolism. This study aims to explore the age- and sex-specific distribution of BUN among healthy Chinese adults. The BUN values corresponding to the 1st, 2.5th, 50th, 97.5th, and 99th percentiles for any specific age in both sex were calculated. Some studies suggested that elderly females showed a higher protein synthesis rate compared to males, females have less muscle m ass[6,7]. These findings indicate that the level of BUN in serum may change dynamically with age. The value of serum BUN between males and females differ, irrespective of the same age group. Few studies have been performed to establish reference intervals for serum BUN, taking into account the difference between gender and a ge[8]. Establishing age- and gender-specific reference intervals for BUN for the local population is critical and of utmost importance

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