Research On Salivary Zinc As A Screening Indicator Of Zinc Deficiency In Children And Relationships Between25(OH)D And Nocturnal Enuresis In Children

【Objective】Zinc is one of the essential trace elements in the body, which is known toplay an important role in growth and development of children. However, it is difficult toassess zinc deficiency in children because of the absence of characteristic clinical signs.Serum zinc is the most widely used biochemical indicator of zinc status. But venous bloodsampling is very difficult for children and their parents have poor compliance, which makeit more difficult to diagnose zinc deficiency and assess efficacy of zinc supplementationfor children in clinic. Peripheral blood mononuclear cells (PBMC) metallothionein-2A(MT-2A) mRNA is considered to be an effective marker of zinc status. However, theoperation is complex and little used in clinic. The early manifestation of zinc deficiency isdecreased taste acuity. Salivary carbonic anhydrase VI (CAVI), a zinc-dependent enzyme,is correlated with taste function. Therefore, we studied the relationship between salivaryzinc and taste acuity and the effect of zinc supplementation on salivary zinc, andcompared the usefulness of salivary zinc as a biomarker of zinc status with serum zinc,PMBC MT-2A mRNA and CAVI. The objective of this research was to evaluate thepossibility of salivary zinc as a screening indicator of early zinc deficiency.【Methods】From November2012to March2013,309children were recruited from fivekindergartens in Taizhou, Zhejiang Province, China. These children’s ages ranged from4to7years old.164boys (53.1%) and145girls (46.9%) participated. Sodium chloridesolutions and glucose solutions were used to evaluate taste acuity. ICPS was used tomeasure serum zinc levels and salivary zinc levels. RT–PCR method was performed tomeasure PBMC MT-2A mRNA levels. ELISA was employed to measure CAVI levels.Zinc gluconate was used for zinc supplementation. After a duration of zinc supplementation of1month for zinc-deficient children, we measured changes of theaboved biomarkers to determine the feasibility of salivary zinc to diagnose zinc deficiencyand assess the efficacy of zinc supplementation.【Results】1. Serum zinc levels were higher in native children than immigrant children (P<0.05). There was no association between serum zinc and children’s age and gender (P>0.05).2. After adjusting for age and gender, there was no relationship between serum zinc,PBMC MT-2A mRNA, salivary zinc, CAVI and salt taste acuity（P>0.05）. Serum zinc andsalivary zinc were significantly associated with sweet taste acuity (P <0.05). A negativelinear relationship was observed. There was no relationship between PBMC MT-2AmRNA, CAVI and sweet taste acuity(P>0.05).3. Taste acuity was improved after zincsupplementation (P<0.05). Zinc supplementation could increase serum zinc levels,salivary zinc levels and PBMC MT-2A mRNA levels (P<0.05). CAVI levels also increasedafter zinc supplementation, but not significantly (P>0.05).【Conclusions】1. Serum zinc and salivary zinc were negatively correlated with sweettaste acuity. Sweet taste is more sensitive to reflect changes in zinc status than salt taste.2.Serum zinc, salivary zinc and PBMC MT-2A mRNA are reliable biomarkers which couldreflect changes in zinc status in response to supplementation.3. Salivary zinc may replaceserum zinc to be used as a screening indicator of early zinc deficiency.4. For children withtaste disorder due to zinc deficiency in clinic, salivary zinc and sweet taste test could beused together to evaluate the efficacy of zinc supplementation. 【Objective】Vitamin D has been recognized to contribute to various physiologicalprocesses. However, no study has investigated serum25-hydroxyvitamin D [25(OH)D]concentrations in children with nocturnal enuresis (NE) in the English literature. In thepresent study, serum25(OH)D concentrations were measured and the information aboutnighttime bedwetting was collected in children of five kindergartens in Taizhou toinvestigate whether there was any relationship between25(OH)D and NE.【Methods】From November2012to March2013,247children were recruited from fivekindergartens in Taizhou, Zhejiang Province, China. These children’s ages ranged from5to7years old.134boys (54.3%) and113girls (45.7%) participated. LC-MS/MS was usedto measure serum25(OH)D levels and the structured questionnaire was administered tothe parents of all children to collect data. The questionnaire consisted of two sections. Thefirst section contained questions on the demographic characteristics of the child. Thesecond section consisted of questions about nighttime bedwetting of the child. Vitamin Ddeficiency was defined as serum25(OH)D concentrations below20ng/ml.【Results】The prevalence of NE was7.3%in the group of children with25(OH)Dconcentrations that exceeded20ng/ml; this prevalence was much lower than the17.5%observed in the group of children with25(OH)D concentrations below20ng/ml (p<0.05).After adjusting for potential confounders, serum25(OH)D (≥20ng/ml) was significantlyassociated with NE and represented a protective factor against NE [OR=0.31,95%CI=(0.092,1.0), P <0.05]. A nonlinear relationship between25(OH)D and NE wasobserved. The prevalence of NE decreased with increasing25(OH)D concentrations above 19ng/ml. Additionally, children exhibiting higher frequencies of bedwetting had lower25(OH)D concentrations [5-7times/week:18.3±4.8ng/ml;2-4times/week:20.9±4.1ng/ml;0-1times/week:23.6±6.4ng/ml, P<0.05)].【Conclusions】Low25(OH)D was associated with an increased risk of NE in children.