The analysis of Probability Distribution Functions (PDF) for velocity and magnetic field fluctuations in solar wind reveals that fluctuations around the mean field occur in clusters and are stronger than expected from Gaussian statistics. This phenomenon is called intermittency and is related to the presence of coherent structures in the solar wind. Here we proposed a universal description of PDF in solar wind using a four-parameter function. We describe the evolution of this parameters with increasing frequencies as well as some implications of this empirical model. Finally we establish the connection with the power spectrum and we discuss possible links between the intermittency, coherent structures and the evolution of the turbulent spectrum at ion scales.