The effects of hypothyroidism on the gonadotrophic axis are contradictory, some authors have found that PTU treated rats had diminished concentration of LH on D and P but the preovulatory surge was conserved [25], while others describe a reduced proportion of ovulating rats, but increased preovulatory levels of LH in those rats that ovulated after radiochemical thyroidectomy with 131I [17]. The gene discussed is PLOD1; the disease is hypothyroidism.