Convert negative statistic value to positive bits?

Using Perl/iControl 10.2.0, I am trying to reconstruct the same Statistics output that is shown in the LTM GUI. I have successfully obtained the statistics with the get_statistics method. But some of the statistics return a negative value for some reason I can't figure out. For example, the

 

STATISTIC_CLIENT_SIDE_BYTES_OUT statistic has a Low value of -60548310. Yet in the LTM GUI, the value if Bits (Out) is 102594828624.

 

 

In practice, I have found that multiplying the Low value by 8 is a reliable conversion method when the statistic is not negative. Can someone provide some insight into how I can reliably convert a negative STATISTIC_CLIENT_SIDE_BYTES_OUT statistic value into a positive Bits value?