First of all, we thank our colleagues Drs Machens and Dralle for their comments because it is good that published articles are not simply statistical data but that they are able to create a dynamic to clarify doubts and evaluate each study in the right way. With respect to blood donors, I would like to summarize the situation in our country so that readers can then understand how the control group was selected. According to current legislation, blood donation is permitted from the ages of 18 to 65 years regardless of the donor's sex. However, in practice, this upper limit sometimes varies according to medical criteria and according to needs. Thus, it is not unusual (when there is a necessity in our blood donation centers) for blood extractions to be taken from 71- to 72-year-olds who are in good clinical condition and do not have contraindications. In any case, from the hematological point of view, it is not wise for patients older than 75 years of age to donate given that after this age, a patient's medullar blood reserve begins to decrease. In this respect, we would like to add that the donation interval does vary according to a donor's sex: a healthy man can donate every 3 months while a healthy woman can donate every 4 months. The established blood pressure limits are 145/100 mm Hg maximum and 90/50 mm Hg minimum, and the minimum level of hemoglobin for donation is 13 g/dL for men and 12 g/dL for women.
Ríos A, Rodríguez JM, Parrilla P. Associations of HLA-C Alleles With Multinodular Goiters—Reply. Arch Surg. 2006;141(10):1048. doi:10.1001/archsurg.141.10.1048-b