PLOD1 and Gonadotropin deficiency: In premenopausal women presenting with menstrual irregularities, low or inappropriately normal FSH/LH levels along with low estradiol levels (<27.6 pg/mL) [33] suggest gonadotropin deficiency only after other causes of ovulatory dysfunction, such as thyroid-related abnormalities or hyperprolactinemia, have been ruled out [17,29].