Think of your thyroid gland as a clearing house where information flows in and out, to ensure that your whole body achieves homeostasis balance.
Thyroid Stimulating Hormone (TSH) is produced by the pituitary gland in your brain and sent to your thyroid, to ensure a state of balance known as homeostasis, which is maintained by a process of self-regulation, occurs.
TSH tells your thyroid to produce more or less hormones, specifically triiodothyronine (T3) and thyroxine (T4), to make sure you’re functioning optimally. These two hormones regulate many important aspects of your body, including metabolic rate, body temperature, and brain development.
Since the right amounts of T3 and T4 are responsible for maintaining a well-functioning body in many ways, understanding high, low, and normal TSH levels is essential.
What is homeostasis?
Homeostasis and the endocrine system are based on a negative feedback system. When an end organ produces a hormone, these hormones then return to the hypothalamus and pituitary so that the brain and pituitary know that an adequate amount of hormone is being produced.
If any of these organs are damaged, as in autoimmune thyroid disease, and the thyroid gland no longer produces sufficient amounts of thyroid hormone, then this lower level is sensed by the hypothalamus in the brain. Therefore, a large amount of TSH is released in an attempt to produce more thyroid hormones from the thyroid gland.
What could high TSH mean?
According to Joseph Winchell, MD, a family physician at Mount Carmel Medical Group in Pickerington, Ohio, having high TSH usually means one of two things.
The most common is an underactive thyroid gland, or hypothyroidism. If your thyroid isn’t producing enough thyroid-stimulating hormone, your pituitary gland will release more TSH to try to get more T3 and T4 from the thyroid gland. It’s a bit difficult to understand, but having high levels of TSH indicates low levels of T3 and T4.
When a patient reports symptoms such as sudden weight gain, fatigue, low energy, irregular periods or sleep problems, it is possible that it is due to high TSH. Since symptoms of high TSH are also common symptoms of other conditions, the only way to find out is to have a doctor provide you with a blood test to check your TSH levels.
Examining cumulative symptoms over time is also helpful in helping to make a diagnosis.
Euthyroid disease syndrome
Another common diagnosis of elevated TSH comes from non-thyroid conditions, otherwise known as euthyroid syndrome. In this case, sick people, often those hospitalized in intensive care, produce less T3 or T4 because of the disease they have.
What could low TSH mean?
Unlike high TSH, in which only a few conditions present themselves for relatively simple diagnoses, there are many reasons for low TSH. Low TSH means higher levels of T3 and T4 produced by the thyroid gland.
The most common diagnosis is Graves’ disease, which triggers hyperthyroidism. In simple terms, this means an overactive thyroid. In this autoimmune disease, the thyroid becomes overactive as it is attacked by the body’s immune system.
Another example is a syndrome called central hypothyroidism. In this case, your TSH may be low, but you are considered to have hypothyroidism due to damage to the pituitary gland. In this example, the gland does not produce enough TSH to adequately stimulate the thyroid gland to produce T3 and T4. It’s a bit difficult to diagnose, and there’s more work to figure it out.
Exogenous use of the thyroid could also lead to a diagnosis of low TSH. This can happen either by taking too many thyroid hormone replacement medications or by overusing thyroid hormone medications, which could lead to TSH suppression.
The most important things to know about TSH levels
Most often, providers use TSH levels to guide treatment to ensure a person is producing the correct levels of thyroid hormone. It’s important to look at not only TSH test results, but also free T4 and total T3, which could provide more accurate numbers and present a more complete picture of what’s going on and allow your doctor to determine the good treatment plan.
In addition to blood tests, it is important that your doctor knows the full picture of your presenting symptoms and when they occur, as well as any medications or supplements you are taking. To get to the bottom of your problem, your doctor may order further tests, including a thyroid ultrasound.
Since TSH is responsible for creating the hormones T3 and T4, which help regulate much of your body, and because there are so many factors at play in creating or suppressing these hormones, the he use of TSH data serves as a starting point for any in-depth diagnosis. and treatment plan. This can be confusing, especially considering that what is really a normal range for one person is not for another, and levels will change for many reasons.
For example, Dr. Winchell refers to a situation in which TSH suppression is revealed by testing. The doctor’s first reaction would be to reduce the treatment. However, after checking for free T4 or total T3, the full image shows levels within the normal range.
It is an ongoing debate. Ultimately, the standard of care is to treat within the target range for TSH, which is usually between 0.5 and 4.5.
If you go to your doctor complaining of thyroid problems, worrying about symptoms such as fatigue and inability to lose weight, it’s important to remember that while thyroid function plays a role in both in your energy level and in your ability to gain or lose weight, there are many other factors that need to be taken into consideration.
Being tired all the time doesn’t necessarily mean you have a thyroid problem, just like being cold doesn’t automatically mean you have hypothyroidism. An inability to lose weight or gain excessive weight does not mean that your thyroid is abnormal. So while it is appropriate to check in these situations, patients should realize that there are many other factors that could be at play and a wider differential should be considered when you have these concerns.