[Detection methods of diurnal changes in plasma leptin concentrations].

Objectives: The authors evaluated the usefulness of the three mathematical methods used to identify pulses in the diurnal rhythm of leptin concentration variations in blood serum.

Design: In order to perform the evaluation 160 cases of computer-aided pulse simulation were used. Also the evaluation of leptin concentration variations in 2 healthy women (lean and obese) was made.

Materials And Methods: The following were the parameters used as the basis for defining the simulated courses: the average concentration of leptin in 24 hours, the amplitude of the diurnal cycle, the number and amplitude of pulses, the error of leptin concentration in one sample. In 2 healthy women blood samples (0.5 ml) from cubital vein were taken every 10 minutes in 24 hour period. The pulse detection was carried out by means of three methods: threshold with auto-correlation, cluster method and spectral analysis using the Fourier transform.

Results And Conclusions: According to the results of the simulation it can be suggested that the threshold with auto-correlation method is the least sensitive to measurement error of leptin concentration. Threshold and cluster method confirmed the pulse way of leptin release to circulation in clinical study, but the number of pulse occurrences, observed in 24 hour period by means of these methods, was different in the same patients (in obese ranged from 8 to 22 and in lean from 12 to 20). It was observed that after a meal there was a well-marked pulse of insulin release, however, the leptin release pulses were marked in both lean and overweight women at random (had no correspondence with insulin pulses).