Your Ferritin is way too low, at 49; it should be 70-80 and could be as high as 100. Low ferritin means that you have no iron stored... that all the iron you have is what's in your blood. Iron is necessary for conversion of Free T4 to the usable Free T3 thyroid hormone, but it's also necessary for other body processes. We need to have adequate supplies in store.
Did they tell you to supplement your vitamin B-12? At 274, it too is way too low. That's what I meant when I said just being in range isn't good enough. Vitamin B-12 is also necessary for thyroid hormone metabolism, but more important, it's necessary for energy production and proper nerve function. I have permanent nerve damage in my feet because I had low B-12 for a long time and they didn't bother testing it. They kept telling me there was nothing wrong and no reason for my fatigue/lack of energy. I didn't get tested until the damage was done... The older we get, the more likely we are to be deficient in B-12 because we don't absorb it as well.
At only 26, your vitamin D was definitely too low, so it's good that they prescribed pills for you. Taking the medication may not have a direct effect on symptoms, but it will help your overall well-being... Did they give you a dosage that you're to continue taking indefinitely or was it a mega dose that you will take for a short period, then drop down to a lower maintenance dose? You should continue taking vitamin D long term to keep your level up...
The antibody tests would be considered negative since they aren't over the upper reference range... this would go along with the thoughts of Secondary hypothyroidism...
The thing is that it's been long enough now, that you need to have all these things retested again because once the tests are several months old, they're no longer valid. If your current doctor won't retest, you should find a different doctor, because this one will keep you ill due to his unwillingness to test and/or provide treatment...
Well, if you had good doctors, they'd realize that your thyroid hormone levels are too low, whether you have high heart rate or not. When I was very hypo, I had to be put on a beta blocker to slow my heart rate down... that didn't mean I wasn't hypo. Some symptoms can apply to either hyper or hypo and high heart rate is one of them.
A pituitary issue can affect one or more endocrine system... the first thing they need to do is an ACTH stimulation test and check your adrenals (cortisol and GH levels). They need to test LH and FSH which will help determine what's going on with reproductive organs and of course, there's the TSH, that's already been tested, but it needs to be tested again, along with the Free T4 and Free T3 thyroid hormones.
If your current doctor isn't willing to do the proper tests, you should find a new doctor that is willing. Your symptoms definitely indicate hypo and their mentality that you can't be hypo because of high heart rate is simply wrong...
You said you had the other tests done and they're fine... Could you please post the actual results and reference ranges? Sometimes, even if something is within the range, it's not fine. There's a difference between being in range and being functional and optimal.
Different labs do have different ranges; that's very common.
Yes, you should be worried that your levels have dropped.
I'm wondering why you got TSH (Thyroid Stimulating Hormone) tested in October 2017, though and Free T4 (Thyroxine, Free) tested in November. Why weren't they tested at the same time? Or was the blood draw done at the same time and you just didn't get the results together?
In November, your Free T4 was barely in the range; it's too bad there was no Free T3 tested. I'd imagine that would have been quite low as well.
The thing is, with Free T4 as low as it was, we'd expect to see TSH much higher than it was since they work opposite each other... i.e. when thyroid hormones are low, TSH goes high and when thyroid hormones are high, TSH goes low. Since both your thyroid hormone (Free T4) and TSH are low, we'd suspect Secondary hypothyroidism, which is a pituitary problem instead of a thyroid problem. With secondary hypothyroidism, there's a problem with the pituitary/hypothalamus axis so there's not enough TSH to stimulate the thyroid to produce thyroid hormones.
What symptoms are you having? Please post a list, though I can almost imagine what they are... :-(
If I were you, I'd call the doctor and request another set of tests, this time insist that it includes Free T3 because Free T3 is the hormone that's used by almost every cell in your body it's much more important than, either Free T4 or TSH. If your doctor refuses to order another set of tests or refuses to order Free T3, don't hesitate to find a different doctor.
While you're requesting tests, ask to be tested for vitamin B-12, vitamin D, and ferritin. All of these are necessary for the proper production and/or metabolism of thyroid hormones.