In Reply We appreciate the comments of Eisenga et al regarding our classification of the anemias in our Original Investigation.1 They question our choices of the levels of ferritin and B12 used to classify patients as iron-deficient or Vitamin B12–deficient, respectively. Their questions raise the more general issue that there is no universally accepted cut-off level by which either anemia can be diagnosed using a single test. We concede that we might have misclassified a few participants in either direction for each type of anemia. With respect to iron deficiency, others have suggested that ferritin values in the general range we selected (<40 ng/mL) are reasonable for a presumptive diagnosis of iron deficiency anemia.2 Indeed in the study cited by Eisenga et al,3 ferritin levels 45 to 75 ng/mL were suspected to be related to iron deficiency only on the basis of blood film evaluation, not the demonstration of absent iron stores, as was the case for those with levels less than 45 ng/mL. Even some patients whose levels were less than 45 ng/mL had iron stores present. Thus misclassification may occur in either direction. Similarly, B12 levels have limited sensitivity and specificity, and while a value of less than 200 ng/L more likely indicates true deficiency than higher levels, some individuals whose values are greater than 200 ng/L could have relative B12 deficiency.4,5 Whether this mild deficiency would be sufficient to cause anemia is uncertain. Nevertheless, while some degree of misclassification may have occurred, because testosterone treatment corrected anemias of “known” cause as well as unexplained anemia, our conclusion that testosterone improves both types of anemia in older men who have low testosterone appears solid. We emphasize that this conclusion applies only to older men with low testosterone and not to men who are anemic but have normal testosterone. With respect to the suggestion by Eisenga et al regarding the mechanism by which testosterone increased hemoglobin, we agree that testosterone may have acted by suppressing hepcidin.6

中文翻译：

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对老年人步态速度和活动受限的强化血压控制

在回复中 我们感谢 Eisenga 等人在我们的原始调查中对我们的贫血分类的评论。他们质疑我们对铁蛋白和 B12 水平的选择，分别用于将患者分类为缺铁或维生素 B12 缺乏。他们的问题提出了一个更普遍的问题，即没有普遍接受的临界值，通过该临界值可以使用单一测试诊断出任何一种贫血。我们承认，对于每种类型的贫血，我们可能在任一方向上错误地分类了一些参与者。关于缺铁，其他人建议我们选择的一般范围内的铁蛋白值 (<40 ng/mL) 对缺铁性贫血的推定诊断是合理的。 2 事实上，在 Eisenga 等人引用的研究中，3 铁蛋白水平 45 至 75 ng/mL 仅根据血涂片评估怀疑与铁缺乏有关，而不是铁蛋白储备不足的证明，如水平低于 45 ng/mL 的情况。甚至一些水平低于 45 ng/mL 的患者也存在铁储备。因此，任何一个方向都可能发生错误分类。同样，B12 水平的敏感性和特异性有限，虽然低于 200 ng/L 的值比较高水平更可能表明真正缺乏，但一些值大于 200 ng/L 的个体可能存在相对的 B12 缺乏症。4,5这种轻度缺乏是否足以导致贫血尚不确定。然而，虽然可能发生了某种程度的错误分类，因为睾酮治疗纠正了“已知”原因的贫血和不明原因的贫血，我们的结论是睾酮改善了睾酮低的老年男性的两种类型的贫血。我们强调，该结论仅适用于睾酮水平低的老年男性，不适用于贫血但睾酮水平正常的男性。关于 Eisenga 等人关于睾酮增加血红蛋白机制的建议，我们同意睾酮可能通过抑制铁调素发挥作用。 6