The results of study of possible deviation of plasma irregularities caused by the action of neutral air turbulence in the lower ionosphere from isotropy are presented in this report. The consideration was based on an analytic expression for the three-dimensional (3D) spectrum of such irregularities. By integrating the 3D spectrum, ID spectra were derived for two different directions of its possible measurements. It was shown that the spectra of the irregularities are quite close to an isotropic one, although there are some their deviations from isotropy on the edges of the considered wave-number range. These deviations result from changes in a relative role of the geomagnetic field (more important for larger wave numbers) and the gradient of mean plasma density (more important for smaller ones) in creating the plasma irregularities of different scales. Estimations of slope of the irregularity spectra and of the root-mean-square level of plasma fluctuations were made too. There is good agreement between the obtained results and the data gathered during a rocket-radar simultaneous experiment in the lower ionosphere at high latitudes.