Lammi-Keefe C J, Lickteig E S, Ahluwalia N, Haley N R
Department of Nutritional Sciences, University of connecticute, Storrs 06269, USA.
J Am Diet Assoc. 1996 Mar;96(3):247-51. doi: 10.1016/S0002-8223(96)00075-2.
To determine the day-to-day variation in biochemical measures of iron status in a group of elderly women with rheumatoid arthritis compared with a group of healthy elderly women.
Venous blood samples were collected from each subject on 3 nonconsecutive days during a 2-week study period; subjects had fasted overnight. Variability in hemoglobin level, hematocrit value, serum iron concentration, total iron-binding capacity, transferrin saturation, serum ferritin concentration, and plasma transferrin receptor level was determined.
Two groups of women, one with rheumatoid arthritis (n=10) and another that was apparently healthy (n=10).
Variance component analysis was used to estimate the biological variation (sigma square day) and analytic variation (sigma square rep) for each iron index. The coefficient of variation (CV) for each variance component was calculated: coefficient of biological variation = CV day, coefficient of analytic variation = CV rep, and coefficient of a single future determination = CV fd.
The CV rep for all iron indexes was smaller than the CV day in both groups. The CV day was considerably higher for serum iron concentration and for transferrin saturation than for the other indexes in both groups (16.6% and 16.6% in healthy subjects and 33.6% and 28.2%, respectively, in subjects with rheumatoid arthritis). The higher CV day for serum iron concentration and transferrin saturation translated into a higher CV fd for these indexes. Because of the higher variance for these two indexes, more sampling days were required for reliable estimates. CV day and CV fd for plasma transferrin receptor level were relatively low.
These findings corroborate our previous finding that variation of serum ferritin concentration in the elderly is lower than that demonstrated in younger populations. This aging effect persists in the presence of rheumatoid arthritis. Fasting appeared to improve reliability in the determinations for serum iron concentration and transferrin saturation. Variability estimates for the indexes other than serum iron concentration and transferrin saturation were not altered by the inflammation of rheumatoid arthritis. Plasma transferrin receptor level is a reliable index for assessing iron status in populations with rheumatoid arthritis.
确定一组患类风湿性关节炎的老年女性与一组健康老年女性相比，铁状态生化指标的每日变化情况。
在为期2周的研究期间，于3个非连续日从每位受试者采集静脉血样；受试者已禁食过夜。测定血红蛋白水平、血细胞比容值、血清铁浓度、总铁结合力、转铁蛋白饱和度、血清铁蛋白浓度及血浆转铁蛋白受体水平的变异性。
两组女性，一组患类风湿性关节炎（n = 10），另一组看似健康（n = 10）。
采用方差成分分析估计每个铁指标的生物学变异（σ²日）和分析变异（σ²重复）。计算每个方差成分的变异系数（CV）：生物学变异系数 = CV日，分析变异系数 = CV重复，单次未来测定的变异系数 = CV fd。
两组中所有铁指标的CV重复均小于CV日。两组中血清铁浓度和转铁蛋白饱和度的CV日显著高于其他指标（健康受试者中分别为16.6%和16.6%，类风湿性关节炎受试者中分别为33.6%和28.2%）。血清铁浓度和转铁蛋白饱和度较高的CV日导致这些指标的CV fd较高。由于这两个指标的变异性较高，因此需要更多的采样日才能进行可靠的估计。血浆转铁蛋白受体水平的CV日和CV fd相对较低。
这些发现证实了我们之前的发现，即老年人血清铁蛋白浓度的变异性低于年轻人。这种衰老效应在类风湿性关节炎存在的情况下依然存在。禁食似乎提高了血清铁浓度和转铁蛋白饱和度测定的可靠性。类风湿性关节炎的炎症并未改变血清铁浓度和转铁蛋白饱和度以外指标的变异性估计。血浆转铁蛋白受体水平是评估类风湿性关节炎人群铁状态的可靠指标。
