Objective:To discuss the relationship between the geographic environment and blood urea nitrogen(BUN) reference values of the healthy people,and to explore the distributional rule of BUN reference values of the healthy people,and to provide the scientific foundation for establishing the BUN reference value standards of different areas.Methods:A total of 23 geographic factors and 33 521 BUN reference values of healthy adults measured by 403 medical facilities from 23 provinces,4 municipalities and 5 autonomous regions were collected.The spatial autocorrelation analysis was used to determine the spatial autocorrelation of the sample data;the correlation analysis was used to detect the factors which correlated significantly with the BUN reference values;the multiple linear regression,principle component analysis and ridge regression analysis were respectively used to construct the predicted models;the paired-sample t test was used to choose the optimal model;the distribution map of BUN reference values was built by geostatistic analysis.Results:There were 5 geographic factors,latitude(X2),altitude(X3),annual mean temperature(X5),annual mean relative humidity(X6) and annual precipitation(X7),correlated significantly with the BUN reference values.The regression equation of optimal model was Y^=5.112+0.000 127 1X2+0.000 094 61X3-0.000 140 5X5-0.000 136 8X6-0.000 139 1X7±0.531 0;the distribution map of predicted values of the BUN reference values was obtained.Conclusion:The overall trend of BUN reference values is low in the east and high in the west.The BUN reference value is negatively associated with the altitude.If the geographic data of a certain region could be obtained,the BUN reference value of this region will be predicted.

Intravenous leiomyomatosis is a rare type of tumor that is histologically benign but biologically invasive. It originates from the smooth muscle of the uterine or the uterine vein. It can grow through the uterus and extend into the pelvic cavity, or grow along the veins without invading the wall of the venous vessel itself. The tumors are estrogen-dependent and can metastasize through the bloodstream. Thus, in addition to continuous growth, some tumors exhibit isolated growths in the venous system and heart chambers or show disseminated growth in the lungs, although distant metastasis to other regions usually do not occur. Currently, there is limited research on this disease, the majority of which are case reports, surgical experience summaries, and differentiation from ordinary gynecological myomas in terms of pathogenesis and radiological diagnostic experience. There are two main theories on the origin of the disease: uterine smooth muscle and smooth muscle of the uterine veins. Some studies have verified the role of estrogen, progesterone receptor-related pathways, and angiogenesis in the development of the disease. The clinical symptoms of this disease are varied, depending on the affected area. In the early stages, when the tumor only affects the pelvic cavity, patients show mild symptoms resulting from pelvic organ compression. When it progresses to the inferior vena cava and heart, patients show more complex symptoms resulting from venous return obstruction, cardiac obstruction, and hemodynamics appearing. Different institutions have proposed different disease staging and classification strategies for different clinical purposes. Some are based on the affected area of the lesion; others are based on the size of the tumor. Although surgery remains the main treatment for this disease, the specific surgical approach, adjuvant drug therapy, and prognosis still need further exploration.

Intravenous leiomyomatosis is a rare type of tumor that is histologically benign but biologically invasive. It originates from the smooth muscle of the uterine or the uterine vein. It can grow through the uterus and extend into the pelvic cavity, or grow along the veins without invading the wall of the venous vessel itself. The tumors are estrogen-dependent and can metastasize through the bloodstream. Thus, in addition to continuous growth, some tumors exhibit isolated growths in the venous system and heart chambers or show disseminated growth in the lungs, although distant metastasis to other regions usually do not occur. Currently, there is limited research on this disease, the majority of which are case reports, surgical experience summaries, and differentiation from ordinary gynecological myomas in terms of pathogenesis and radiological diagnostic experience. There are two main theories on the origin of the disease: uterine smooth muscle and smooth muscle of the uterine veins. Some studies have verified the role of estrogen, progesterone receptor-related pathways, and angiogenesis in the development of the disease. The clinical symptoms of this disease are varied, depending on the affected area. In the early stages, when the tumor only affects the pelvic cavity, patients show mild symptoms resulting from pelvic organ compression. When it progresses to the inferior vena cava and heart, patients show more complex symptoms resulting from venous return obstruction, cardiac obstruction, and hemodynamics appearing. Different institutions have proposed different disease staging and classification strategies for different clinical purposes. Some are based on the affected area of the lesion; others are based on the size of the tumor. Although surgery remains the main treatment for this disease, the specific surgical approach, adjuvant drug therapy, and prognosis still need further exploration.