When my levels are off, my feet get insanely cold and often turn blue. It's a pretty reliable marker for me to get tested. The tiredness and weight stagnation come on more slowly, so for me they're subtle symptoms until it's pretty bad. The inhumanly freezing feet, though, super obvious!

My endocrinologist has me tested every 3–4 months. I've found that taking my Synthroid w/ a full glass of water first thing in the morning, then waiting a full hour before eating or drinking anything but water has increased my energy & reduced the brain fog. Previously, I took a few sips of water & waited 35 mins. I've always waited 4 hours before taking any vitamin or mineral supplements.

It may be placebo effect, but you've nothing to lose by trying it.

in general every 3-6 months, though when i start a different dose it's 6 weeks later for a retest. I've only been on meds for a little over a year and a half, and I don't think I've had my blood tested this many times in the rest of my life.

I see the endocrinologist once a year unless there is a blip in the testing. Sometimes I have a cyst on the thyroid that needs monitoring more frequently. My blood work has been steady and so no need to come in but once a year.

I will say that I highly recommend those that are not seeing an endocrinologist and just seeing a GP to make an appt. with the specialist. Several years ago our area lost the one endocrinologist in the area. (he passed away) I moved my files to my GP. The GP had me all over the place, changing dosage to often. I was hypo then hyper(due to over medication) . . . just back and forth. Finally the area hospital got a new endocrinologist in the area and I made an appt. with him. I've been going to him for 10 years and he stabilized my dosage almost immediately.

I must admit I was excited to think that having hypothyroidism was the cause of my weight gain and had visions of loosing weight with proper medication. But the truth is my being overweight had more to do with what I ate and the lack of exercise.
So here I am on MFP fixing that problem.

Happy to find this site!

I'd also add look for an endo that looks beyond the blood tests. I saw a few doctors and two endos before I found one that looked beyond TSH (not kidding!). It wasn't until I found the last endo, that I even had antibodies checked -- which confirmed the Hashi's diagnosis. I couldn't believe that I'd literally seen 4 doctors before I even had such things tested. My TSH has been all over the map in the past few years, and is really totally unreliable for those of us with Hashi's. I had one endo look at my TSH and say he couldn't help me -- he didn't even look at free T3 and T4, let alone antibodies or other vitamin/mineral deficiencies.

So, all endos or GPs are not created equal and I found GPs (at least with my various insurance) to know little to nothing about thyroid issues. It wasn't until I got more educated myself and starting asking questions, that things got moved along. I finally have an endo that is interested in the blood tests, but also looks for other deficiencies (vitamin D, magnesium, iodine, etc.) and listens to the my symptoms and treats based upon all these factors. I personally use natural dessicated thyroid (Nature-throid) now and prefer it to synthroid. I think this is in part because the natural dessicated thyroid has both T4 and T3, both of which numbers were low in my tests.