Human growth hormone (GH) is a heterogeneous protein hormone consisting of several isoforms. The peptide is encoded by 2 genes, GH1 and GH2, both give rise to multiple variant forms. Post-translational modification including oligomerization increases the variation (Baumann 2009). Approximately 14% of circulating human Growth Hormone (GH) is in dimer or oligomer form, this number varying from 0 to 100% (Kublickas et al. 2006). The biological activity of these oligomeric forms is variably diminished when compared to the monomer (Baumann 2009).