I just got my annual blood test results back and my TSH was flagged as low at 4.0. I pulled up last year’s level (July 2023) and it was 4.7. Everything else tested was WNL (as always).
Given that this TSH isn’t far below the cut-off for the normal range, should I pursue any preventative action right now?
Did you have a full thyroid panel? With antibodies? Have you ever had a thyroid ultrasound? Do you have any symptoms of being hyperthyroid, like a racing heart beat, anxiety, being overly warm?
Low TSH means your brain isn’t calling for thyroid hormone production, because something else is producing thyroid hormone. Common causes are thyroid tumors or an autoimmune disease called Graves. Not sure that there are really any preventive measure to keep those things from progressing, but you should definitely discuss screening with your doctor, especially if you have any symptoms.
Thanks! I don’t have any symptoms and this wasn’t a full thyroid panel, just the regular annual wellness blood panel.
I’d just prefer to do something before those symptoms appear, if it was possible. Dr. Google suggested beta blockers or, apparently the same thyroid med that my cat is taking. 
I would expect a full thyroid panel, including antibodies, as a next step. Thyroid ultrasound is a strong possibility, and at the very least, good to have a baseline.
Jumping to treatment without understanding if your thyroid hormones are actually high would be premature. TSH value isn’t really something you treat. It’s an indication that the brain thinks the thyroid is either under or over producing. It’s like a volume knob. Figure out what the thyroid is actually doing, and why, and go from there.
That you have no symptoms of excess thyroid hormones is a good sign!
That’s great advice. I’m currently wrangling with my doctor because she wants to change my levothyroxine amount based on TSH, with all the other thyroid measures being in normal range. I thought I’d try just ignoring the suggestion and see if she keeps chasing me for it.
Rebecca
Yeah, dependence on TSH for making treatment decisions in hypothyroidism is sucky for a lot of people 
I’m sorry your doctor is pushing for a change despite you (hopefully!) feeling good and a normal thyroid panel otherwise.
I feel awful, but there are so many possible culprits for that: over 25 years of RA, fibromyalgia, failed kidneys (on dialysis). So I go by the rest of the thyroid panel.
Rebecca
I’m confused about your TSH result. Is it 4.0 or 0.4? The reference range for TSH is about 0.5-5.0 mIU/mL, so 4.0 would be a normal result. But, 0.4 is a little low.
Do you take levothyroxine for thyroid replacement? If so, then probably all you need to do is lower your dose and then recheck in a couple of months. If you’re not on levothyroxine then a full thyroid panel would be a good idea.
You’re right, it’s 0.40 now, down from 0.47 a year ago. So not far below the low baseline, but dropping.
Not taking any meds.
Insist that your doctor order a full thyroid panel, which looks at the levels of (some of) the actual hormones in your blood. And keep in mind that ‘reference range’ is only valid at the population level, it doesn’t tell you what’s normal or optimal for your individual body.
Although it’s focused on hypothyroid, this site will give you more information than you ever wanted to know about thryoid hormones, tests, etc. And the problems in how too many doctors manage thyroid. https://stopthethyroidmadness.com/
Something important for antibodies test. Make sure it’s for graves (TraB) is the test results. What most doctors order for antibodies test is the one for hashimotos. Regular doctors should not be treating Graves’ disease because it is more complex than hypothyroidism which still personally either a very knowledgeable physician is okay but really you need a referral for endocrinologist. The thyroid controls so much so it can make a lot of things way worse and affect you much earlier than most people realize. I thought I had been symptomatic for roughly a year. Really we’re realizing it’s probably closer to 2-3 years. We just thought it was other stuff going on.
this just popped up in my email and thought it might be helpful to you.
I have hyperthyroidism. I do not drink coffee nor eat anything before a blood test and absolutely no biotin supplements for 4 days before a test as all of these things will effect your test. I found this information through a group on facebook.
Is it the caffeine in the coffee or something else and for how long do you avoid it before the bloodwork ?
It’s suggested that it’s the caffeine. I just avoid it the day of the test. I hope this helps you.
It does thanks!!
I have been taking synthroid for years since my thyroid was damaged by chemo. My doctor told me I also needed to take a vitamin D supplement. So every morning I would take both. Forward about 15 years, and I read an article about vitamin supplements interfering with the absorption of synthroid. Switch to Synthroid am and D3 pm. Lost 42 lbs and had to adjust doseage.
Synthroid made me feel like crap in a few ways. I stopped taking it because I’m a bad patient and started taking vitamin d and b12. Several months later, all of my thyroid tests are in the normal range (for years they were borderline or low even on Synthroid). So I found that interesting. I also lost 20lbs.
I’m not saying I recommend that approach, but the results were interesting to me. I have a full thyroid panel done every 6 months but if this next one is also normal we’ll push it out to yearly if there are no symptoms/other reasons to test.
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