I take synthroid for hypothyroidism, I also take ritalin, My question is will the ritalin speed up the metabolism of the synthroid. I lately have felt tired and it is getting hard to concentrate, symptoms I had that led to the hypo dx. Since then I have had my TSH checked a couple of times but always in the morning right after (hour or so) i take the synthroid. My TSH is normal at that time but this early in the day and I usually haven't taken ritalin at all yet that day. I'm wondering if the TSH is accurate at this time or should I take it in the morning go to school like normal (ritalin) and have it checked in the afternoon to see if there is an affect on TSH level?