Die Hypoferritinämie des Sportlers ist kein sicheres Indiz für Eisenmangel [High Serum Ferritin Levels Have Low Sensitivity for Iron Deficiency in Athletes]

Iron deficiency is commonly diagnosed by serum ferritin [sFer] determination, iron deficiency anaemia from reduced mean cellular volume (MCV). [sFer] shows a high variance if inflammation or liver dysfunction are present. Athletes often present with hypoferritinaemia. This study was designed to evaluate the relation of total body haemoglobin mass (tHb) which is commonly elevated in athletes to [sFer]. In the present study 56 trained (TR), 72 moderately trained (MT) and 31 untrained (UT) male individuals were investigated for peak oxygen uptake (VO2max), serum iron, [sFer] soluble transferrin receptor [sTfr], serum erythropoietin [EPO], haemoglobin concentration [Hb] haematocrit (Het), MCV blood volume (BV), and plama volume (PV). TR and UT individuals differed significantly in VO2max, tHb, PV, and BV (all p<0.01). [sFer] correlated negatively with tHb (r=-0.31,p<0.05), BV (r=-0.38,p<0.05) and max (r=-0.54,p<0.01) but not with EPO, [Fe], [sTfr], MCV, [Hb], Het, and PV. Since a negative correlation of [sFer] and tub was found, an iron storage shift from the reticuloendothelial system (RES) to the erythroid system could have occurred. This is only pathological if functional iron deficiency occurs, as suggested by increased [sTfr]. Possible causes of functional iron deficiency are gastrointestinal microhaemorrhage, menstrual blood loss and EPO-doping. True iron deficiency should be treated by dietary means or iron supplementation. Iron misuse instead has severe side-effects and uncritical addition of iron to the athlete's nutrition should be avoided