The Variability of Non-hemoglobin Iron.

In this paper data on the range of variation of non-hemoglobin iron in human blood will be presented. The significance of these variations in relation to (a) the calculation of hemoglobin, or oxygen capacity from the determinations of total blood iron, and reciprocally, (b) the deduction of values for total blood iron from determinations of hemoglobin or oxygen capacity, will be considered. Because of the difficulties inherent in the direct determination of hemoglobin there has been a widespread interest in the indirect methods of approach. Of these the oxygen capacity is the most accurate, but there has been an idea in the minds of many that it is a formidable procedure and, as an alternative, there has been a growing tendency to arrive at values for hemoglobin by measurements of total blood iron. Wong (1), Fowweather (2), Sackett (3), Dupray (4), and others have calculated hemoglobin values from determinations of total blood iron. Kennedy (5) believes that total blood iron can be correlated with oxygen capacity and hemoglobin content as determined by colorimetric methods. Murphy, Lynch and Howard (6) have proposed a new index, the "iron index," obtained by dividing the milligrams of iron in 100 cc. of blood by the number of red blood cells in the same volume, as an expression of the concentration of iron in the red blood cells. The validity of these values rests on the assumption that all the iron of the blood is contained within the red blood cells, or combined with hemoglobin, and behaves as a single variable. In 1898 Abderhalden (7) first showed that there was more iron in the blood of various animals than could be attributed to the hemoglobin alone. He found that the non-hemoglobin iron amounted to 10 per cent of the total blood iron in the ox, 3.6 per cent in the horse, and 6 per cent in the rabbit. Since then Ehrlich and Lazarus (8), Rosin and Jellinek (9), Erben (10), Seiller