The study was approved by the Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (The Institutional Review Board Approval Number: TJ-C20160115). The exclusion criteria included 10 indicated collinearity among the variables 11. For participants less than 18 years old, their informed consent was obtained from their parents or legal guardians. The included study subjects aged between 14 and 85 years and were considered healthy after a physical examination.

The study was performed at the Department of Health Management Center and approved by the Ethics Committee of Tongji Hospital, Huazhong University of Science and Technology. Thus, establishing age- and gender-specific reference intervals for BUN for the local population is critical and of utmost importance. To accurately diagnose the patient's condition and avoid subjective factors, it is necessary to evaluate accurately whether the BUN value is within the normal range. Most clinical laboratories establish the reference intervals from medical literature or the diagnostic test manufacturer 9, 10. Few studies have been performed to establish reference intervals for serum BUN, taking into account the difference between gender and age 8.Īt present, the clinical reference range value of BUN is non-standard and not uniform, both nationally and abroad. However, the value of serum BUN between males and females differ, irrespective of the same age group. These findings indicate that the level of BUN in serum may change dynamically with age. Some studies suggested that elderly females showed a higher protein synthesis rate compared to males, although females have less muscle mass 6, 7. With an increase in age, there is a sex difference in protein turnover. Several studies reported that environmental and other factors, such as geographical change, climate change, gender, age, dietary structure, physical functioning affect BUN values 5. They suggested that BUN plays an essential role in predicting cardiovascular events caused by acute heart failure and is a prognostic or a neurohormonal activation biomarker in heart failure 3, 4. found that BUN predicts survival in patients admitted with heart failure (HF) and not creatinine 2. Therefore, BUN plays a vital role in diagnosing and evaluating renal function 1. The blood BUN level is mainly dependent on its rate of glomerular filtration and tubular reabsorption. Similar content being viewed by othersīlood urea nitrogen (BUN) is a nitrogenous end product of protein metabolism and also produced in the liver by the breakdown of dietary proteins. 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. 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. Thus, the serum BUN values increased by 0.21 mmol/L for males and 0.282 mmol/L for females per 10 years.

Multiple linear regression analysis confirmed that the positive associations of BUN levels and age were statistically significant after adjusting confounding factors ( P < 0.001).

However, eGFR showed a negative correlation with the BUN reference value (P < 0.0001) in both sexes. BUN values showed a positive correlation with body mass index (BMI), cholesterol, and blood sugar (P < 0.0001). Males had a higher median BUN value compared to females (4.6 mmol/L vs. A total of 24,006 BUN values from healthy adults (14,148 males and 9858 females) were included in the cross-sectional study. This study aims to explore the age- and sex-specific distribution of BUN among healthy Chinese adults. Blood urea nitrogen (BUN) is a nitrogenous end product of protein metabolism.

Normal bun range