Learn more about Hypothyroid Testing with this guide by Aviva Romm.
Just recently a patient came into my practice feeling fatigued, moody, was having heavy periods, no libido, and was bothered by constipation. She also wasn’t sleeping well – waking up too early in the morning and unable to fall back to sleep, and she’d gained 7 pounds in just a couple of months even though she hadn’t changed her eating habits.
All are signs of hypothyroidism.
We talked. She really didn’t feel that stress was causing her symptoms – nothing in her life was really that troublesome. She had no outlier symptoms that suggested another diagnosis. She was pretty sure something was wrong with her thyroid so she’d asked her primary doctor to check her thyroid labs before scheduling to come see me for an more integrative medicine consult. He’d checked her thyroid stimulating hormone (TSH) test only, and told her that since it was still in the normal range, even though it was at the upper end of normal, she did not have a thyroid problem. He sent her on her way suggesting that maybe an antidepressant would be good to consider.
But her labs weren’t normal. One step over a very thin line and she’d have had a slam dunk diagnosis of the most common thyroid problem: hypothyroidism. And in fact, this is what I diagnosed. She started appropriate treatment and her energy and symptoms quickly began to improve! This is a typical story.
Getting to The Bottom of Thyroid Testing
While not all hypothyroid-like symptoms turn out to be a problem with the thyroid or thyroid hormones, we do know that statistically, hypothyroidism is an under-diagnosed condition. In fact, only about half of Americans with a thyroid problem know they have one, and it is estimated that this can be as many as 4-10% of Americans
Hypothyroidism is the most common thyroid problem, and Hashimoto’s disease, an autoimmune form of hypothyroidism, is the most common form of all. Women are much more likely than men to have thyroid problems. Hypothyroidism can appear at anytime but is especially common after childbirth and is prevalent in woman in their 40s and 50s.
Yet so many doctors seem reluctant to do an adequate work-up of thyroid function. Some even refuse! This seems strange given how common thyroid problems are, and yet they are quite willing to freely prescribe antidepressants. My patient’s doctor was doing just what we were all told to do in medical school – check the TSH and if that’s within what we were told is the normal range, there’s no problem. But there’s much more complexity to thyroid testing than that! Sadly, so many women are left believing that their symptoms of depression, fatigue, joint aches, weakness, weight gain and more are all in their head! Perhaps this has even happened to you. In reality, your symptoms could be due to hypothyroidism.
What is the Thyroid?
The thyroid is a butterfly-shaped gland that sits at front of your neck and sets your entire metabolic rate. Thus it controls your weight, whether you feel sluggish or energetic, mentally crisp or foggy, cheerful or blue, and is involved in the control of everything from your cholesterol to your female hormones.
When your thyroid is not functioning optimally, you can feel dull, tired, constipated, gain weight, your skin gets dry, your hair can become dry and even fall out, your muscles and joints might ache, your periods become irregular, you might have fertility problems, brain fog, sugar and carb cravings (because your body is desperate for energy!), high cholesterol even if your diet is amazing, and a host of other large and small symptoms.
What is Hypothyroidism?
Hypopthyroidism is a term used to describe a decreased metabolic state that is due to inadequate amounts of – or functioning of – thyroid hormone. Ninety-five percent of all cases are due to what is called “primary hypothyroidism.” This means that the thyroid gland is acting sluggish – or sometimes barely responding at all. This can be due to a number of reasons ranging from leaky gut to autoimmune disease.
Alternatively, we can be producing thyroid hormones effectively, but we can have “thyroid hormone resistance” similar to the way we can have insulin resistance. Our cells are not picking up and effectively using the active thyroid hormone we are making. We can also be making enough of the inactive form of thyroid hormone but not be effectively converting it to the active form.
While hypothyroidism can also be due to more serious problems in the hypothalamus and pituitary, this is rare. However, chronic or substantial stress can suppress the pituitary gland enough to interfere with thyroid hormone production.
Symptoms of hypothyroidism include:
- Increased sensitivity to cold
- Dry skin
- Unexplained weight gain
- Cravings for sugar and carbohydrates
- Puffy face
- Muscle weakness
- Elevated blood cholesterol level
- Muscle aches, tenderness and stiffness
- Pain, stiffness or swelling in your joints
- Heavier than normal or irregular menstrual periods
- Thinning hair
- Slowed heart rate
- Impaired memory (“Brain fog”)
Because these symptoms are so common to so many women, hypothyroidism is often dismissed as “just normal symptoms” or depression! One patient of mine was accused of overeating by her primary doctor as the cause of her weight problem when she actually had a thyroid problem!
The 6 Key Thyroid Tests
There are 6 key tests that can unlock the mystery of your thyroid function and are what your doctor should be looking at. Thyroid testing should be simple to obtain from your primary doctor or local lab. However, the nuances may take some skill to interpret, depending on the results, and your doctor might be resistant to ordering more than the TSH test. That’s where an open-minded endocrinologist or a skilled Functional Medicine doctor can be of help!
In this blog I will discuss key thyroid testing. In a subsequent blog I will discuss interpreting the results to understand your situation, the variations that can point to whether you have an underfunctioning thyroid gland, thyroid hormone conversion problems, or thyroid hormone resistance. In yet another blog I will address the causes, prevention, and treatment of thyroid autoimmunity.
In my practice, if my patient’s symptoms are highly suggestive of hypothyroidism, I will run the entire thyroid panel described below right up front. If there are other diagnoses that are equally likely, I will run just the first 3 tests (Panel 1), and if these come back borderline or positive for thyroid or thyroid hormone problems, I will then add in the remainder of the test panel (Panel 2). I will also sometimes recheck test results for TSH, FT3, and FT4, if normal in a newly symptomatic patient, in 6-12 weeks, because I’ve occasionally seen initial testing be normal then a short time later, voila – the tests come back confirming the problem.
Thyroid Stimulating Hormone (TSH)
Thyroid Stimulating Hormone (TSH) is produced in a part of your brain called the pituitary gland. The job of TSH is to tell the thyroid gland that it’s time to get busy producing more thyroid hormone. When the healthy thyroid gets this chemical message, it produces two hormones: triiodothyronine (T3) and thyroxine (T4),
The normal range for TSH is somewhat controversial. Most labs consider the upper range to be between 4 and 5 mU/L. However, many experts – even in conventional endocrinology – believe that the upper end of normal is actually more like 2.5-3 mU/L. This is based on the fact that when Americans without any hypothyroid symptoms have this test done, that is the most usual upper range.
Many integrative and functional medicine doctors find that their patients feel their best at an upper limit of 1.5-2 mU/L.
My patient was one of these people. At a TSH of 4 she was really at the upper limit of normal, over the preferred upper limit according to some docs, and well over the 1-2 mU/L upper range! This controversy and discrepancy of opinion over the normal upper range for TSH is one of the most common reasons that women get under-diagnosed for hypothyroidism and suffer with unnecessary symptoms that can seriously interfere with health and quality of life.
In most cases hypothyroidism occurs because the thyroid gland is sluggish – that is, it is having trouble producing T3 and T4. This can be due to a variety of reasons ranging from nutritional deficiencies to autoimmunity. So TSH gets pumped out in a higher amount to try harder to stimulate the thyroid gland into action. Think of it like this: You are TSH. Your best friend’s house is the thyroid gland. When you go to visit your friend you knock on her front door. If she doesn’t answer, what do you do? You knock louder to get a response. In just the same way, the TSH amps up to knock louder, hoping to get an answer. That’s why an under-functioning thyroid shows up as high TSH on lab tests. However, TSH can be normal in the presence of hypothyroidism in some cases, and you can still be having the symptoms of low thyroid when TSH is normal because of poor conversion of T4 to T3 (see below) or because of thyroid hormone resistance at the level of your cells.
When stress is suppressing the pituitary gland enough to interfere with producing TSH, you might see low or normal TSH levels in the presence of low thyroid hormone production (T3 or T4), and hypothyroid symptoms.
Thyroid Hormones (T3 and T4)
Triiodothyronine (T3) and thyroxine (T4) are the hormones produced by your thyroid gland. T4 is produced in a much larger amount and is then converted to T3, the active form of the hormone, as needed to up-regulate metabolic functions. T3 and T4 are sent out into your bloodstream where they are responsible for the thyroid’s actual work of controlling your metabolism. Free T3 (FT3) and Free T4 (FT4) are called this because they are not bound to proteins in your blood, making them free to perform their work in your cells – keeping your metabolism appropriately revved up for your optimal health.
Measuring FT3 and FT4 is important because they are the indicators of thyroxine and triiodothyronine activities in the body. A high TSH and low FT4 and FT3 indicate hypothyroidism. A normal TSH, normal FT4, and low FT3 can indicate T4 to T3 conversion problems, and a normal or high TSH, normal FT4 and high FT3 can indicate cellular resistance to FT3 which can still lead to hypothyroid symptoms because the active hormone can’t get to the cell to do its job.
Thyroid antibody testing is ordered to diagnose autoimmune thyroid disease and distinguish it from other forms of thyroid dysfunction.
The two thyroid antibody tests that I order are Thyroid peroxidase antibody (TPOAb) and Thyroglobulin antibody (TgAb). Some people do have an autoimmune thyroid condition but don’t initially test positive. If positive, antibody testing can be repeated every six months to trend improvement while you are working with an integrative physician to address possible underlying causes.
Reverse T3 (rT3)
Reverse T3 is the third most abundant form of thyroid hormone. When your body wants to conserve – rather than “burn” – energy, it will divert the active T3 into an inactive “reserve” form. This might happen when you are sick, under stress, or undernourished. If TSH and FT4 look ok, but FT3 is low this can be because it is being diverted into rT3 – which will be elevated. It is worth checking rT3 if there are obvious symptoms suggesting hypothyroidism, but the typical tests aren’t demonstrating low TSH or low FT4. There is some controversy amongst conventional doctors about the utility of this test – I personally find it very useful.
If labs return showing that there is hypothyroidism, then I also test for deficiencies of selenium, iron, and zinc and make sure there is adequate dietary intake or supplementation if needed, and look for environmental factors that can interfere with iodine utilization, for example, fluoride and bromide exposures from water and flame-retardant products, respectively. I will then also start to look more closely for other underlying causes, for example, gluten intolerance, heavy metal exposure, and other environmental triggers.
Talking with Your Doctor About Thyroid Testing (or Switching Doctors)
As a doctor, I can tell you that in medical school we are taught that doctors know best. But this is often not the case. You are your body’s best expert. After all, you live with you all the time! And you have a right to ask for basic testing and receive it. We’re not talking about tens of thousands of dollars in MRI’s and CT scans here – we’re talking about modest amounts of blood work.
That said, do discuss your symptoms with your doctor because there’s a lot of hype in the natural medicine and natural products world, and your doctor is possibly just trying to protect your from the opposite problem – getting OVER-diagnosed or misdiagnosed with a thyroid problem – and believe me, I’ve also had many patients who were put on thyroid medications by integrative practitioners when these meds were not needed.
If you are unable, however, to have an honest conversation with your doctor, if you feel your doctor is not listening or is condescending, then that’s another issue. You should be able to have mutually respectful conversations with your care provider, to get the answers you are seeking, and to be able to explore your concerns. If you can’t, then figure out whether the obstacle is in your being unable to speak up because of a perceived power differential (many of us become weak in the knees when we face our doctors, especially if we feel vulnerable about our health) or whether your doctor is just not communicating respectfully. And make the change!