Objective: To evaluate beta-endorphin secretion in euprolactinemic cases of luteal phase defect (LPD).
Design: Serial blood samples from the 18th to the 26th day of the menstrual cycle were assayed for beta-endorphin, progesterone (P), estradiol (E2), and prolactin (PRL) in cases of LPD and controls. Diagnosis of LPD was based on determinations of serum P and premenstrual endometrial biopsy.
Setting: From Cairo University Hospitals. PATIENT, PARTICIPANTS: Twenty-six women with LPD and 8 normal fertile women (controls) were chosen.
Interventions: None.
Main outcome measures: beta-Endorphin, P, E2, and PRL concentrations were determined by the corresponding 125I radioimmunoassay.
Results: Plasma beta-endorphin level in cases of LPD varied from 2.58 to 9.14 pmol/L, whereas the level of controls varied from 2.41 to 5.57 pmol/L. The mean value of plasma beta-endorphin in cases of LPD was significantly higher than that of controls by 146% (P less than 0.0005). In spite of the significant decrease of serum P in cases of LPD, serum E2 level did not differ significantly from that of controls.
Conclusion: The possible sources of beta-endorphin rise and its implication in the etiology of LPD are explained.