An international haematological survey.

Haematological surveys of adult population samples were conducted simultaneously in 12 countries, all but one of which are in Europe. Haematological estimations on samples from nine of the countries were made in one central laboratory. Differences between countries in the mean levels of haemoglobin (and haematocrit and red cell count) were found to be relatively small, and the prevalence of levels below the arbitrary WHO levels for anaemia were, on the whole, low. In males, the evidence suggests a fall in haemoglobin level throughout adult life, which increases slightly in advanced age. In females, there is no evidence of any important relationship between age and haemoglobin level.