Rubbish! Even NICE don't recommend doctors looking at total cholesterol any more. They look at the components - HDL, LDL, Triglycerides, and the ratios. Your doctor is way out of date, and possibly ticking boxes somewhere instead of doing a bit of research. .... 5.1????? 0.1 above the standard? Ridiculous.
Just for your benefit
HDL is all good cholesterol and yours is brilliant
Triglycerides are the baddies and yours are brilliant
Try completing this
http://www.hughcalc.org/chol-si.php