Department of Andrology, University Hospital Hamburg-Eppendorf, Hamburg, Germany. a.spiess@uke.uni-hamburg.de|Department of Andrology, University Hospital Hamburg-Eppendorf, Hamburg, Germany. a.spiess@uke.uni-hamburg.de|Department of Andrology, University Hospital Hamburg-Eppendorf, Hamburg, Germany. a.spiess@uke.uni-hamburg.de