Abstract 26

We have demonstrated previously, using an specific immunofluorometric assay (IFMA) that elevated LH levels in adolescents with PCO can not be ascribed to increased pulse amplitude but to markedly raised baseline levels. In this study we have analyzed the nocturnal LH profile by deconvolution analysis in order to assess whether the increased plasma LH levels are the result of increased production rate or increased endogenous half life. Spontaneous LH secretion was assessed in 10 PCO patients (CA: X±SD: 16.6±2.2 years. BMI: 23.7±5.4) presenting amenorrhea or oligomenorrhea and 8 normal cycling controls (CA: 16.4±1.8 years. BMI: 22.6±3.3). Blood samples were obtained every 20 minutes from 7PM to 7AM. Serum LH levels were determined by IFMA (DELFIA). Intra and interassays Cvs were lower than 7%. Statistical significance was assessed by Student's or Mann Whitney's tests. Results: Plasma LH had a longer half live (104.7±28 vs 76.3±14 min. p<0.001) in PCO patients. These patients had also a 2-fold higher production rate (43.0±15 vs. 21.2±5.1 UI/I/day: p<0.001), higher mean LH concentration (9.1±4.4 vs. 3.2±0.76 UI/I: p<0.001) and greater approximate entropy score (Ap En: 1.1±0.10 vs. 0.86±0.23: p<0.001) than controls. The mean pulse amplitude was similar in both groups (0.60±0.38 vs. 0.53±0.34 UI/I). Conclusion: This study shows for the first time that at least during adolescence LH molecules with prolonged half life are released in PCO patients and that these patients have increased LH production rate. An increase in basal (non-pulsatility) LH release or a prolongation or asymmetry of the LH pulse shape could account for an apparently prolonged half-life explaining the current LH data in PCO. It remains to be determined whether this alteration is the cause of the consequence of the inadecuate steroid secretion in PCO syndrome.