ABSTRACT
Generally, anovulation is diagnosed based on the assessment of both gonadotrophins FSH and LH along with a measurement of serum estradiol levels. In case LH as well as FSH serum concentrations are low and estradiol levels are also in the lower limit of detection, a central defect should be suspected. Generally, such defect leads to a hypogonadotropic hypogonadism, which is classified according to the World Health Organization classification as WHO 1 anovulation (1). In case gonadotrophin levels are elevated and estradiol serum concentrations are low, a peripheral, that is, ovarian defect should be suspected. Typically in these women, FSH levels are higher compared to LH serum concentrations. This so-called monotropic rise is caused by a lack of inhibin feedback upon FSH secretion from the pituitary and is pathognomonic for ovarian failure. In general, these women are classified as suffering from hypergonadotropic hypogonadism and categorized into the WHO 3 class (1). Finally, in the majority of cases FSH and LH levels as well as estradiol concentrations are normal. These cases are generally referred to as having normogonadotropic normo-estrogenic anovulation, and they are categorized into the WHO 2 class (1). Depending on what definition is used, a smaller or greater number of these women can also be diagnosed as having polycystic ovary syndrome (PCOS) (2,3) (see Figure 11.1).
