Human luteinizing hormone (hLH) is a glycoprotein synthesized by the anterior lobe of the pituitary gland. This hormone consists of two subunits: α and β. The α subunit of LH is similar to the α subunit found in both the FSH and TSH glycoprotein hormones (which are also synthesized by the pituitary gland) as well as the α subunit of hCG (produced by the placenta). However, the β subunit of each of these hormones are unique. Therefore, the specificity of these four hormones are due to the β peptide chains. It is to be noted that the α chain by itself has no biological activity.