Background: Iron deficiency (ID), worldwide a common affection is associated with reduced performance, fatigue and increased risk for infections. Athletes are a risk-population due to a higher prevalence of restrictive diets or exercise-induced inflammation. Particularly in athletes, the diagnosis of ID based on unspecific symptomes or routine laboratory diagnostics with ferritin is not always reliable. The goal of this study was therefore to discover if a new diagnostic approach adding zinc protoporphyrin (ZnPP) or soluble transferrin receptor (sTfR) in the routine assessment of ID in athletes is helpful or even necessary.