Firstly, don't say low carb if you feel the Dr. would frown. Say that you are cutting out sugars and starches and processed foods and trying to eat lean meat and lots of vegetables and salad. And if you want dessert, you have some fruit.

Look in the Atkins or Eades books for their lists of pre-plan tests to have.
Here are some quick suggestions :
blood pressure (obvious)
Cholesterol: total, and preferably both HDL & LDL & ratio
Triglycerides
Thyroid: TSH but ask for T3 & T4 as well

She'll probably do a BUN & creatinin (kidney function) and possibly liver function, hemoglobin & others since you have no record or baseline.