Variation of luteinizing hormone and androgens in oligomenorrhoea and its implications for the study of polycystic ovary syndrome.

We measured luteinizing hormone (LH) and androgen concentrations in patients at different phases of the oligomenorrhoeic cycle and compared the results with those of patients with normogonadotrophic amenorrhoea. Several blood samples separated by >/=7 days were obtained from each of 72 patients with oligomenorrhoea and 18 with normogonadotrophic amenorrhoea. The oligomenorrhoeic cycle was divided into five phases: the postmenstrual phase week 1 (day 1-7) and week 2 (day 8-14), the specific oligomenorrhoeic phase (SOP, day 15 after a menstruation to day 21 before the next menstruation), the possibly peri-ovulatory phase (days 21-11 before menstruation) and the premenstrual phase (days 10-1 before menstruation). Samples obtained in the possibly peri-ovulatory phase were excluded. Within individuals LH concentrations were significantly higher during the SOP than during all other phases of the oligomenorrhoeic cycle (paired t-test, P = 0.0001-0.03). In contrast to the other phases of the oligomenorrhoeic cycle, no significant differences in gonadotrophins, androgen or oestradiol concentrations were found between the SOP and normogonadotrophic amenorrhoea. In oligomenorrhoea timing of blood sampling influences the measurement of LH and androgen concentrations, and the accurate interpretation of these measurements requires that the dates of menstruation both before and after the sample is taken should be known. In patients with oligomenorrhoea blood samples should be obtained during the SOP, when the endocrinology is comparable with that of normogonadotrophic amenorrhoea.