Changes in blood hemoglobin concentration of middle-aged healthy men.

Because data on age changes in blood hemoglobin concentration (Hb) originate from cross-sectional studies, they are biased as a result of disease-associated changes in Hb and selective mortality of subjects with high and low Hb. The purpose of this project was to study longitudinally the age-associated changes in Hb among military aviators. Data were extracted from the medical files of 807 subjects, of whom 213 were healthy. There was an increase in Hb among men 20 to 45 years old. In all three types of analysis (in cohorts, in groups with different ages at diagnosis of the first chronic disease, and in groups of healthy subjects in service at different ages), subjects who were healthier (eligible for flying until a later age, later age at diagnosis of the first chronic disease, and no chronic disease at later age) had lower Hb and a steeper increase in Hb with age.