I'm late to this party, but still wanted to answer. I take a split dose - one in the early a.m. and one mid-afternoon. When I know I am having blood work for my thyroid I schedule it for as early as possible and I skip my morning dose and take it directly after my blood work. This is based on the STTM website and questions from the STTM facebook feeds. It has worked in my favor and allowed me to up my dosage when needed. I would never stop it a day (or several days) before, though. We NEED these meds as regularly as possible!