Haemoglobin concentration [Hb] is a routine and well established parameter in clinical and sports medicine. Interpretations of changes in [Hb] are difficult since they can occur due to changes in erythrocyte and/or blood volumes. As a result changes in [Hb] can lead to false diagnosis as for example in case of occult blood loss, dilution anaemia, or when judging the haematological status of endurance athletes. In contrast, the total haemoglobin mass (tHb-mass) represents the absolute mass of circulating haemoglobin in the body, which in turn reflects the oxygen transport capacity.

A high quantity of haemoglobin molecules is important in two ways. On the one hand it directly increases oxygen transport (1g keppra levetiracetam transport 1.39ml of oxygen) and on the other hand it increases blood volume by facilitating venous return which is a prerequisite for a high maximal cardiac output. tHb-mass, therefore, is an important parameter to assess the aerobic aspect of physical performance.

Figure: Influence of total haemoglobin mass (tHb-mass) on endurance performance (VO2max).
Data of pre-dialysis patients from Clyne et al. Nephron 67: 322-326, 1994

The relationship between blood volume and tHb-mass as well as the influence of both parameters on [Hb] is illustrated in the Figure.

Figure: Haemoglobin concentration [Hb] as a function of blood volume and haemoglobin mass (tHb-mass)

It becomes obvious that tHb-mass linearly depends on blood volume over a broad range in a sex-related manner. The scattering of tHb-mass for a given blood volume reflects different [Hb] which may be related to differences in maximal cardiac output. We herewith point out that [Hb] and tHb-mass are different physiological parameters which may exert different effects on endurance performance.

In this table you find reference values for haemoglobin mass and blood volume in healthy adults (according to Schmidt and Prommer 2010, ESSR) 

The wide range in tHb-mass and blood volume shows that these parameters are very individual and depend on various factors as: 

• genetic predisposition
• sex 
• anthropometry 
• age 
• training state 
• altitude exposure

For more information see tab “Science”