Thurnham D I, McCabe G P, Northrop-Clewes C A, Nestel P
Northern Ireland Centre for Food and Health, Faculty of Life and Health Sciences, University of Ulster, Coleraine, UK.
Lancet. 2003 Dec 20;362(9401):2052-8. doi: 10.1016/s0140-6736(03)15099-4.
Vitamin A deficiency adversely affects child morbidity and survival. This deficiency is estimated by measurement of plasma retinol concentrations, but because plasma retinol is reduced by clinical and subclinical infection, this proxy measure can lead to overestimation. Infection and trauma are accompanied by rises in concentrations of acute-phase proteins in plasma. We aimed to estimate vitamin A deficiency more accurately by measuring changes in plasma retinol and acute-phase proteins associated with subclinical infection or convalescence.
We analysed data for concentrations of plasma retinol and one or more acute-phase proteins (alpha1-acid-glycoprotein, alpha1-antichymotrypsin, C-reactive protein, or serum amyloid A) from 15 studies of apparently healthy individuals. We generated summary estimates of differences in retinol concentrations for incubation, early, and late convalescent phases of infection between people with none and those with one or more raised acute-phase proteins. We compared these groups in two, three, and four group analyses. We also compared a subgroup of apparently healthy preschool (1-5 years) children with results from all other studies.
For all four proteins, retinol values were much higher in people with normal concentrations of protein, than in individuals with raised concentrations (16% higher for alpha1-antichymotrypsin, 18% for alpha1-acid-glycoprotein, 25% for C-reactive protein, and 32% for serum amyloid A). Estimates of the reduction in plasma retinol for individuals with infection compared with healthy individuals, were 13% (incubation), 24% (early convalescent), and 11% (late convalescent). Estimates of vitamin A deficiency in individuals with no raised acute-phase proteins (healthy group) were much the same as those obtained by adjustment of plasma retinol concentrations in the whole group using acute-phase proteins.
We recommend that surveys to estimate vitamin A deficiency should include measurements of serum C-reactive protein and alpha1-acid-glycoprotein concentrations. Information about acute-phase proteins will enable plasma retinol concentrations to be corrected where sub-clinical infection exists, and the healthy sub-group to be identified.
维生素A缺乏对儿童发病率和存活率有不利影响。这种缺乏是通过测量血浆视黄醇浓度来估计的，但由于临床和亚临床感染会降低血浆视黄醇水平，这种替代指标可能会导致高估。感染和创伤会伴随着血浆中急性期蛋白浓度的升高。我们旨在通过测量与亚临床感染或康复相关的血浆视黄醇和急性期蛋白的变化，更准确地估计维生素A缺乏情况。
我们分析了来自15项针对明显健康个体的研究中血浆视黄醇和一种或多种急性期蛋白（α1-酸性糖蛋白、α1-抗糜蛋白酶、C反应蛋白或血清淀粉样蛋白A）浓度的数据。我们生成了在感染的潜伏期、早期和晚期康复阶段，急性期蛋白未升高的人与一种或多种急性期蛋白升高的人之间视黄醇浓度差异的汇总估计值。我们在两组、三组和四组分析中对这些组进行了比较。我们还将一组明显健康的学龄前（1至5岁）儿童的亚组结果与所有其他研究的结果进行了比较。
对于所有四种蛋白，蛋白浓度正常的人的视黄醇值远高于蛋白浓度升高的人（α1-抗糜蛋白酶高16%，α1-酸性糖蛋白高18%，C反应蛋白高25%，血清淀粉样蛋白A高32%）。与健康个体相比，感染个体血浆视黄醇降低的估计值分别为13%（潜伏期）、24%（早期康复期）和11%（晚期康复期）。急性期蛋白未升高的个体（健康组）的维生素A缺乏估计值与通过使用急性期蛋白对整个组的血浆视黄醇浓度进行调整所获得的估计值大致相同。
我们建议，估计维生素A缺乏情况的调查应包括测量血清C反应蛋白和α1-酸性糖蛋白浓度。有关急性期蛋白的信息将能够在存在亚临床感染的情况下校正血浆视黄醇浓度，并确定健康亚组。
