That frequent question, “Could it be my thyroid?” in answer to your tiredness, weight gain and thinning hair inevitably is closely followed by this question, “Isn’t there extra testing that you can do for my thyroid? I heard it doesn’t always show up with the first testing.” What about those extra thyroid tests?
“What a great question,” I reply. “Let’s talk a little bit about that extra testing.”
This “extra testing” seems to be the rage these days. Everyone knows about it but few really know what it is and what it means for their health. It’s kind of like going to a fancy dinner. You know those extra utensils have a purpose but have no idea what they are for or when to use them.
So, what is the extra testing?
By extra thyroid testing, you are asking to test for antithyroid antibody testing. When testing your thyroid for abnormalities, we start by checking the hormone levels themselves. That makes sense – if you think something is wrong with the thyroid, you would want to know how well it is functioning. These tests include TSH (thyroid stimulating hormone), T4 (thyroid hormone) and T3 (thyroid hormone). These are values for the thyroid HORMONE levels in your blood stream.
Antithyroid antibodies are an additional levels l of thyroid testing. They do NOT test the hormone levels but rather test for antibodies in your blood stream to the thyroid itself. Antibodies are our body’s defense system. Antibodies to your thyroid tell us if your body’s immune system is working against your thyroid.
Why do Antithyroid Antibody levels matter?
As stated above, your thyroid hormone levels are initially checked through blood work to determine the amount your thyroid is producing. If your T4 and T3 are LOW, this is considered HYPOthyroid, or low thyroid. If your T4 and T3 are HIGH, this is considered HYPERthyroid, or high thyroid. There are multiple causes for these diseases, one of which is caused by your body’s immune system attacking your thyroid.
Antibodies are elevated in diseases such as Hashimoto’s Hypothyroid (low thyroid levels) or Graves Disease (high thyroid levels). These antithyroid antibodies PREDICT the likelihood of progression into thyroid disease in patients who have unclear thyroid hormone results. Abnormally high antibody levels mean that it is more likely your thyroid will not be able to function properly in the future.
What tests are ordered?
- Thyroglobulin Antibody – positive in Hashimoto’s thyroiditis (Autoimmune disease showing low thyroid levels)
- Thyroid peroxidase Antibody – positive in Hashimoto’s thyroiditis
- TSH Receptor Antibody – positive in Graves Disease (Autoimmune disease showing high thyroid levels)
Does that affect your thyroid treatment?
Yes, likely in the LONG term. If your thyroid levels are already significantly off, you are going to need treatment regardless of your antibody levels. If your labs are mixed (Ex: TSH is mildly high and T4 is normal), antithyroid antibody levels will help predict your risk of progression into overt disease state in the FUTURE. They help Doctors with predicting what will happen to your thyroid.
Let me provide two examples for comparison: Let’s start with me for obvious reasons. I have Hashimoto’s thyroiditis. When I was initially diagnosed, I was the example above. My TSH was mildly elevated but T4 and T3 levels were normal. This is called subclinical hypothyroid and is the grey zone of thyroid replacement. I was tired and gaining weight but I was also a medical student with a child. My antithyroid antibody levels were drawn and were elevated.
What did that mean? Well, that is a good question. My primary Doctor sent me to the endocrine specialist who said just that. Good question. He actually gave me two option: I could start a low-dose treatment or wait and recheck in a few months. Being a medical student, I opted to start a low-dose replacement. And guess what happened? Nothing, nothing happened. I felt the same and lost no weight.
So, after a few months I quit taking it. My thyroid levels continued to bounce back and forth for years after that. Until about a year ago, when they took a steady downward spiral. My antibodies had stepped it up a notch and I now really needed thyroid replacement. I started that and guess what happened? I actually felt less tired but still didn’t lose weight. Just my luck.
Two Thyroids, Two Different Stories
Another example – my sister. We share this lovely thyroid disease, as is not uncommon. She was initially diagnosed when my Dad, a surgeon, looked across the table and said, “You have a goiter, your neck is huge. You should get that checked out.” Thanks, Dad. Her lab work showed an elevated TSH, low T4 and T3 and elevated antithyroid antibodies. This is your typical Hashimoto’s thyroiditis picture.
My sister started replacement with medication. She needed more with time but has never gone back. She is on a much higher replacement level than I am and definitely feels a difference if she misses a day of her medication. You could say her thyroid is more needy than mine, not that I’m saying that.
These two cases of “positive extra testing” had two different courses. Both showed positive antithyroid antibodies but that effect on the thyroid itself differed. And the thyroid function IS the most important aspect in treatment.
So, how do you know if you need the extra testing?
Really, this isn’t something you need to worry about. Your Doctor can handle this. If you have your thyroid levels drawn and they come back with mixed results, your Doctor will likely direct the extra testing or recommend rechecking in a few months.
The time when this may be helpful from a patient standpoint comes in family history. If you have 2 sisters and a Mom with Hashimoto’s thyroiditis, that information will be helpful to your Doctor in formulating a plan in terms of testing.
Simple Solution: The infamous “extra thyroid” testing does exist, it’s not just a myth. It is testing for your body’s immune response to your thyroid and predicts FUTURE thyroid disease in patients with borderline thyroid hormone results. You can trust your Doctor to know when this test will be helpful.
For more on guidelines for Thyroid Disease testing, check out:
American Academy of Family Physicians: https://www.aafp.org/afp/2015/0601/od1.html
US Preventative Task Force:
For more Blog Posts on Thyroid testing, Tiredness, and Weight Gain: