The level of serum ferritin of 226 selected subjects, aged 20 to 93, showed an age-related tendency to rise and in every age studied it was higher in males than in females. This finding is considered to be a consequence of the activation of the reticuloendothelial system and of the increase of iron storage with ageing.

In 30 synchronized arteriosclerotic, but otherwise apparently normal, aged patients, a circadian rhythm can be demonstrated for plasma iron and total iron binding capacity, but not for serum ferritin. The features of the two rhythms are similar to those observed in adult subjects. In women an acrophase-shift of the two rhythms in comparison to men has been observed.