This article is a study of the normal renal cortical thickness. It concluded that the mean thickness is 9.1 mm, being the left renal cortical thickness and the male renal cortical thickness slightly longer that the right and female.
Link to the article
To quote this article in bibliography:
Adibi A., A. Emami, H. Salehi, M. Martinpour. “Renal Cortical Thickness in Adults with Normal Renal Function Measured by Ultrasonography." Iran Journal of Radiology 5, no. 3 (2008): 163-166. doi: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.825.2018&rep=rep1&type=pdf