Dr. Martin Bidlingmaier is Head of the Endocrine Laboratory, and he leads the Neuroendocrine Research Group in the Department of Internal Medicine at the Ludwig-Maximilians-University of Munich. Martin conducts clinical and basic research, particularly focusing on the development and validation of laboratory methods to diagnose and monitor pituitary and adrenal hormones, physiology, pathophysiology and biomarkers of growth hormone action, and endocrine aspects of doping in sports. In this episode, we discuss his work identifying new biomarkers and developing novel methods to measure growth hormone and detect growth hormone doping. He describes how growth hormone isoforms and the formation of complexes can help distinguish doping, and how the protein soluble α-klotho has emerged as a potential biomarker that may be useful in anti-doping analyses.