New nucleic acid that binds to gonadotropin releasing hormone, useful for treating and diagnosing overproduction of hormones, e.g. endometriosis

Nucleic acid (I) that binds to gonadotropin releasing hormone (GnRH), especially the human peptide, is new. Independent claims are also included for the following: (1) preparing and/or identifying nucleic acids (Ia), particularly (I), that bind to GnRH; (2) preparing L-nucleic acid (Ib) that binds to GnRH having the natural configuration; (3) complexes of GnRH and (I); (4) kit for detecting GnRH that comprises (I); and (5) screening for GnRH agonists.