Pituitary LH reserve suggests high risk of bulimia in amenorrheic women.

The present study was aimed at investigating a) the risk of having bulimia in a heterogeneous population of secondary amenorrhea; b) the LH and FSH secretion under basal and stimulated conditions (GnRH challenge) according to the presence of bulimic risk in our study population; c) the clinical and endocrine factors predictive of the bulimic risk in amenorrheic women. Amenorrheic women (n=73; age: 23.1+/-4.8 yrs; BMI:20.2+/-2.2 kg/m2) filled in a self rating scale for bulimia (BITE) and were classified accordingly, as being at low risk (score <10), at medium risk (score between 10 and 24), and at high risk (score > or =25) of having bulimia. In each subject basal mean plasma LH levels were calculated over one hour, sampling every 10 minutes, while in a subgroup of 45 patients the area under the curve (AUC) of plasma LH and FSH levels following a challenge with two doses of GnRH (10+10 microg, every two hours), sampling every 15 minutes, was also evaluated. High risk of bulimia was present in 12.3\% of the population whereas 45.2\% showed a low risk and 42.5\% were at medium risk of developing the disorder. Mann-Whitney U test revealed that basal LH values were differently distributed with significantly lower levels (P<0.046) in amenorrheic women at high risk of bulimia in comparison with amenorrheic women at low risk. The AUC of LH secretion following the first challenge of GnRH was significantly higher in amenorrheic women with a high risk of bulimia in respect with both groups of women at low (P<0.034) and medium (P<0.009) risk. A similar result was found with FSH AUC following the first GnRH challenge (P<0.04 high risk vs low risk and P<0.014 high risk vs medium risk). In a multiple regression analysis, the best model predicting the risk of bulimia (BITE total score) included both the LH response to GnRH challenge and BMI. In conclusion, when facing secondary amenorrhea at first consultation, long before a precise pathophysiologic diagnosis of the disease, low basal plasma LH levels and LH response to GnRH challenge may allow one to suspect the presence of abnormal eating pattern of bulimic type.