Analysis Of Vitamin D Level In Healthy Children Aged 1～7 Years Old In Henan Province And Its Clinical Application

Vitamin D is a group of fat-soluble steroid derivatives with biologically activity.Vitamin D has long been recognized as essential for bone and mineral metabolism.Deficiency of vitamin D causes growth retardation and skeletal deformities in children and osteomalacia and osteoporosis in adults.Current literature shows that vitamin D deficiency is associated with an increased risk for nearly all major human diseases such as autoimmune diseases,cancer,cardiovascular,metabolic diseases,and respiratory tract infection.Therefore,vitamin D has gradually aroused people’s attention.Children are the main risk group for vitamin D deficiency,and they are in a critical period of growth.The epidemiological data of Vitamin D deficiency in children and adolescents is lack in the world.In order to realize children’s normal growth and long-term health,vitamin D deficiency should be early detected,early prevented and treated.The defination of vitamin D deficiency,inadequate and the best level of vitamin D is very important,whether to supplement vitamin D and determine the goal of treatment should be achieved depends on these thresholds,but the definition of vitamin D deficiency has not reached a consensus.Respiratory tract infection is the most common disease in children,which is related to children Anatomical features and the imperfect immune system.Prior studies have suggested that vitamin D supplementation is beneficial for reducing the incidence of respiratory infections.However,some clinical studies did not find a correlation between them,thus this viewpoint is controversial currently.Whether vitamin D can affect respiratory tract infection require further study.Objective1.This study regarded healthy children aged 1 ~ 7 years old in Henan provience as the research objects,and the serum 25(OH)D levels were measured by chemiluminescence to establish the serum 25(OH)D reference interval of healthy children aged 1~7 in Henan province.Campared with the current recommended reference standard,to understand the nutritional status of vitamin D in healthy children aged 1 ~ 7 in Henan Province,and to provide evidence for prevention of vitamin D deficiency.2.The serum 25(OH)D were measured in children with respiratory tract infection from 1 to 3 years old,to analyze the relationship between the vitamin D nutrition status and respiratory tract infection in children.Methods1.According to the geographical position and economic development level,392 children aged 1 to 7 years old was selected in Henan provience by the method of stratified cluster random sampling.The sampling of healthy children was divided into 6 age strata: 1 to 2 years old,2 to 3 years old,3 to 4 years old,4 to 5 years old,5 to 6 years old and 6 to 7 years old,and the serum 25(OH)D was measured by chemiluminescence.To establish the serum 25(OH)D reference interval of healthy children aged 1~7 in Henan province according to the WS / T402 – 2012《Define and determine the reference intervals in clinical laboratory》.2.108 children aged 1 to 7 years old with respiratory tract infection were selected as the disease group,and 30 children in the same period were selected as the control group.Analyzed the serum 25(OH)D by chemiluminescence,then compared with the current recommended reference standard[the serum 25(OH)D below 37.5nmol/L is vitamin D deficiey,37.5nmol/L ~ 50.0 nmol/L is vitamin D insufficiency].Results1.The level of serum 25(OH)D in healthy children aged 1~7 years old1.1 General situation of vitamin D level: the mean 25(OH)D level in these children was 42.1(37.0-53.3)nmol/L,the maximum value was 134.2 nmol/L,the minimum value was 27.8 nmol/L.1.2 Comparison of vitamin D level between children aged 1~3 years old and preschool children: there were statistical differences between children aged 1~3 years old and preschool children in the level of serum 25(OH)D and the incidence of vitamin D deficiency(Z=5.631,P<0.001;χ2=11.045,P<0.001).1.3 The serum 25(OH)D reference interval of children aged 1~3 years old and preschool children in Henan provience: the 95% reference interval of serum 25(OH)D in children aged 1~3 years old was(30.5-107.8)nmol/L,and the 95% reference interval of serum 25(OH)D in preschool children was(29.8-91.5)nmol/L.The lower limit and upper limit were lower than the current recommended reference standard(50.0-250.0)nmol/L.2.The level of serum 25(OH)D in children with respiratory tract infection2.1 General situation of vitamin D level: the mean 25(OH)D level in children with respiratory tract infection was(38.9±23.8)nmol/L,the maximum value was 133.8 nmol/L,the minimum value was 28.0 nmol/L.2.2 Comparison of vitamin D level between children with respiratory tract infection and healthy children: compared with healthy children in the same period and 129 children in Henan provience,the serum 25(OH)D level of children with respiratory tract was lower,and the incidence of vitamin D deficiency was higher(H=8.473,P =0.015;χ2 = 21.874,P<0.001).Conclusions1.Based on the analysis of the vitamin D level of healthy children aged 1~7 in Henan Province,the serum 25(OH)D reference interval of healthy children aged 1 ~ 7 in Henan Province was established.Its lower limit and upper limit were lower than the current recommended reference standard.2.The level of vitamin D in children with respiratory tract infection is generally low,and respiratory tract infection may be associated with vitamin D deficiency.