Thyroid Coding - Isthmus Biopsy

Best answers
I'm new in the world of Endocrinology and I'm reaching out to those experts in this area; I have two question regarding thryroid biopsies and isthmus biopsies:

1. Is it necessary to use modifiers LT, RT to identify which side of the thyroid a biopsy is being taken from? Would it be better to use modifier -59 instead to identify separate site?

2. An endocrinologist is taking a biopsy from the isthmus, the center of the thyroid gland, is there a specific CPT I should use? I could not find one. Or should I use 60100 since it is part of the thyroid?:confused:

Thanks in advance for your help.