Thirup Poul
The Danish National Library of Science and Medicine, Copenhagen, Denmark.
Sports Med. 2003;33(3):231-43. doi: 10.2165/00007256-200333030-00005.
This review was undertaken, concerning within-subject biological variation and seasonal variation of haematocrit in normal healthy adults and athletes, to find the limits for natural, intra-individual variation in haematocrit values. The terminology and calculations followed well defined theories, from the field of laboratory medicine, about biological variation. Based on results from 12 studies of 638 normal healthy adults, and which used a sampling interval of 1 day to 1-2 months, the coefficient of within-subject biological variation of haematocrit is 3%. The normal within-subject biological variation (3%) and analytical variation (3%) may explain a relative change of approximately 12% (95% level) [e.g. a change from 0.42-0.47] between two successive haematocrit values, measured with a time interval between 1 day and 1-2 months, in a normal healthy adult. Partly due to haemodilution in warm weather, haematocrit often has a seasonal variation in normal healthy adults; based on results from 18 studies of 24 793 participants, the population mean is approximately 3% lower in summer than winter. Population mean values that are 7% lower in summer than winter have been found in some studies, although no seasonal effect may also be seen, especially in temperate climates. If haematocrit values are sampled at yearly peak and trough time points, with intervals of up to 6 months, a 15% relative change (95% level) can be seen in a normal healthy adult; e.g. a change from 0.42-0.48. Published values for haematocrit in athletes are scarce. It is known that the haematocrit value is influenced by training, especially in the first weeks before a new steady-state is reached. Theoretically, the biological variation in athletes could therefore be greater than in normal individuals. Based on two references addressing the biological variation of haematocrit in athletes, however, the above results are also valid for athletes. Further studies, both in the short term and throughout the seasons, are recommended about the natural variation of haematocrit in athletes.
本综述针对正常健康成年人及运动员血细胞比容的个体内生物学变异和季节性变异展开，旨在探寻血细胞比容值自然的个体内变异限度。术语和计算遵循了来自检验医学领域关于生物学变异的明确理论。基于对638名正常健康成年人的12项研究结果，这些研究采用了1天至1 - 2个月的采样间隔，血细胞比容的个体内生物学变异系数为3%。正常的个体内生物学变异（3%）和分析变异（3%）可能解释了在正常健康成年人中，两次连续血细胞比容值（测量时间间隔为1天至1 - 2个月）之间约12%（95%水平）的相对变化[例如从0.42 - 0.47的变化]。部分由于温暖天气下的血液稀释，正常健康成年人的血细胞比容通常存在季节性变异；基于对24793名参与者的18项研究结果，夏季的总体平均值比冬季约低3%。在一些研究中发现夏季总体平均值比冬季低7%，不过也可能未见季节性效应，尤其是在温带气候地区。如果在一年中的峰值和谷值时间点采样血细胞比容值，间隔长达6个月，在正常健康成年人中可观察到15%的相对变化（95%水平）；例如从0.42 - 0.48的变化。已发表的运动员血细胞比容值很少。已知血细胞比容值受训练影响，尤其是在达到新的稳定状态前的最初几周。因此从理论上讲，运动员的生物学变异可能大于正常个体。然而，基于两篇涉及运动员血细胞比容生物学变异的参考文献，上述结果对运动员同样有效。建议针对运动员血细胞比容的自然变异开展短期及全年的进一步研究。
