Procollagen III amino-terminal propeptide (P-III-NP) is currently monitored in human doping control as a biomarker for growth hormone administration and also in clinical diagnostics using immunoassays. Drawbacks to this approach have been highlighted, and research is ongoing to develop a mass spectrometric method to complement these methods. However, a lack of traceable reference material, the presence of post translational modifications (PTMs), and small blood concentration implicate the development of targeted analytical methods for P-III-NP quantification.