Determination of the frequency of pulsatile luteinizing hormone secretion by time series analysis.

Statistical methods of time series analysis, in particular, spectral analysis, have been used to determine the pulse frequency of LH secretion. This method can detect significant harmonic variation within the data. Six normal women in the early follicular phase of the menstrual cycle were studied at 5 and 15 min sampling intervals and significant dominant pulse frequencies were revealed in five subjects (51-120 min). In addition, a low frequency variation (greater than 6 h) was revealed in four subjects and more rapid frequencies (20 and 13.3 min) were seen clearly in one subject. Comparison of repeat studies on four individuals at the same stage of different menstrual cycles and on two individuals in the same cycle failed to demonstrate differences in five of the six subjects. This method of analysis offers a new approach to the analysis of LH pulse frequency. Realistic comparisons of this frequency between and within individuals can now be made. A new observation of superimposed harmonic components of LH pulsatility has also been recorded.