Whether or not you have a diagnosed thyroid condition, you’ve had this lab value checked at one time or another.
On so many lab panels, maybe even yours, TSH is the only thyroid lab value that’s checked to evaluate how your thyroid gland is functioning. It’s been the gold standard test for decades and is considered the most sensitive and accurate indicator by many endocrinologists and other practitioners. While it gives information about your thyroid, TSH doesn’t tell you exactly how your thyroid is working. It’s more of a secondary marker that tells you how much help your thyroid needs.
Let’s look deeper into what that means and why it should never be the only marker tested to evaluate your thyroid health.
TSH stands for Thyroid Stimulating Hormone.
Just like its name implies, TSH stimulates your thyroid to produce more thyroid hormone. TSH is produced and secreted by your pituitary gland in your brain and works as a signal to “wake up” your thyroid gland so it can get to work.
When your cells demand more thyroid hormone, they send a message to your pituitary, your pituitary sends out TSH, and your thyroid gets stimulated to produce more of your T4 and T3 hormones (about 90% of what your thyroid produces is T4 and most of the remaining 10% is T3).
You can see already how TSH is a secondary marker of your thyroid health. It doesn’t tell you how your thyroid gland is actually working. Rather, it gives information about how much stimulation your thyroid needs so it can work. The more thyroid hormone your cells need, the higher your TSH level rises. Conversely, the less hormone your cells need, the lower your TSH level.
Have you ever used an alarm clock? Let’s pretend for a moment that you are your thyroid gland, your alarm clock is your pituitary, and the alarm’s buzzer is your TSH.
Every morning, you need to wake up so you can send your amazingness out into the world! Your alarm clock sends out its signal, you hear it, you silence the ring, and you get up to start your day. Great! You have a “normal” TSH (the buzzer sounded) so your thyroid gland (you) must be normal too.
But what if your alarm clock needs to keep buzzing to get you up and moving? Did you choose to stay up too late…or have you come down with a horrible head cold and you’re too sluggish…or was it your restless dog who woke you during the night and caused your multiple snooze sessions?
Your alarm clock buzzes over and over again (that’s like your TSH going up), but the real reason you can’t get out of bed can be rooted in anything from self-inflicted lack of sleep, to internal illness, to someone else in the house who’s impacting your wellbeing. It wouldn’t be right to assume that because your alarm clock had to increase its signal to get you up, the underlying problem is because you’re not working well from the inside.
We can take this example even further because the root of the problem could be your alarm clock. Maybe the batteries are dying, the sound isn’t as loud, and the buzzer has to go on buzzing for twice as long until you hear it. Perhaps it’s losing time, and although you get your signal, it’s eight minutes late. Or maybe you forgot to set it, so it doesn’t even know to buzz you out of bed! You (like your thyroid) are working as you should be, but the signaling you’re receiving (your TSH) is out of range because of a problem within the messaging system. This can be caused by a number of things from stress to infection to autoimmune disease and more.
Suffice it to say that a rising TSH level does not necessarily mean that something is “wrong” with your thyroid gland. The problem can be within your thyroid gland, but a number of secondary factors can also be preventing your well-functioning thyroid’s work from appearing “normal.”
Many times a high TSH is seen as the reason to start or increase your thyroid medication. This can never be assumed without checking for deeper contributing factors.
The “normal” range for TSH is quite broad.
Many lab panels will show a normal range from 0.5 to 5.0 mIU/L (milli-international units per liter).
Going back to the alarm clock example…whether you jumped out of bed before your alarm went off (a TSH below zero) or you needed four to five rounds of snooze before your feet hit the floor (a TSH between four and five), both would be considered normal. But is needing your alarm to buzz for five rounds really optimal?
First, you must compare your lab values with your own personal history. If your TSH is 2.5 today, but it was 2.2 six months ago and 1.4 a year ago, things are moving in the wrong direction. Although normal, your values are increasing and that demands a deeper look.
Your TSH can remain normal in many situations when there is actually a problem with your thyroid function.
Some of these can be:
Some root causes of these factors can be:
To fully asses your thyroid function, you need to have a comprehensive panel checked. Each lab value should be evaluated in relation to each other and in regard to your personal history.
A complete panel should include:
Whether you’re talking about TSH or any other lab value, numbers on paper should never be the only indicator of your health! If you feel poorly despite having a “normal” TSH, request a comprehensive evaluation of your thyroid that includes the lab values above. Keep asking questions and advocating for yourself as you seek out a practitioner who will listen to you and provide the whole-body care that you deserve.
If you want to talk more about getting to the root cause of your hypothyroidism or fertility challenges, you can schedule a time for us to talk here.
Aktaş Ş. Vitamin B12 and Vitamin D levels in patients with autoimmune hypothyroidism and their correlation with the antithyroid peroxidase antibodies. Med Princ Pract. 2019 Nov 29. doi: 10.1159/000505094.