What Blood Tests Do Doctors Use To Check Thyroid Function
Doctors may order one or more blood tests to check your thyroid function. Tests may include thyroid stimulating hormone , T4, T3, and thyroid antibody tests.
For these tests, a health care professional will draw blood from your arm and send it to a lab for testing. Your doctor will talk to you about your test results.
Radioactive Iodine Uptake Test
A radioactive iodine uptake test, also called a thyroid uptake test, can help check thyroid function and find the cause of hyperthyroidism. The thyroid takes up iodine from the blood to make thyroid hormones, which is why this is called an uptake test. Your health care professional may ask you to avoid foods high in iodine, such as kelp, or medicines containing iodine for a week before the test.
For this test, you will swallow a small amount of radioactive iodine in liquid or capsule form. During the test, you will sit in a chair while a technician places a device called a gamma probe in front of your neck, near your thyroid gland. The probe measures how much radioactive iodine your thyroid takes up from your blood. Measurements are often taken 4 to 6 hours after you swallow the radioactive iodine and again at 24 hours. The test takes only a few minutes.
If your thyroid collects a large amount of radioactive iodine, you may have Graves disease, or one or more nodules that make too much thyroid hormone. You may have this test at the same time as a thyroid scan.
Even though the test uses a small amount of radiation and is thought to be safe, you should not have this test if you are pregnant or breastfeeding.
Your Thyroid Does Change As You Age
As with any organ, your thyroid may start to function differently as you get older.
Thyroid dysfunction generally occurs in either early adulthood or between the ages of 40 to 50, Lee said. As we get into our 70s, TSH naturally increases, meaning that your thyroid hormone levels may shift to be a little lower. This seems to happen to protect our bodies as we age, with less stress on our heart and metabolic system.
This is important to note, Lee said, because it gives physicians a greater threshold to treat someone who is older who may have higher TSH levels. Alternatively, low TSH levels can be more harmful the older we get.
This isnt to say that if youre young, you dont need to think about your thyroid at all. Thyroid disorders can happen at many different ages, as can lumps.
We do know that the younger population, those in their 20s, 30s and 40s, can develop thyroid nodules, Rao said. The vast majority of these nodules, especially if theyre below one centimeter, are 95% of the time completely benign. But its still important to be aware that they are there, and periodically monitor them.
Also Check: Apple Cider Vinegar And Thyroid
How To Check Your Thyroid
This article was medically reviewed by Ricardo Correa, MD. Dr. Correa is a board certified Endocrinologist. Dr. Correa is the Program Director of the Endocrinology, Diabetes and Metabolism Fellowship at the University of Arizona College of Medicine and was a previous Assistant Professor of Medicine at Brown University. He completed his MD at the University of Panama and completed an internal medicine residency at the Jackson Memorial Hospital – University of Miami. He has been voted one of the 40 Under 40 Leaders in Health by the National Minority Quality Forum in 2019.There are 12 references cited in this article, which can be found at the bottom of the page. This article has been viewed 40,747 times.
The thyroid gland is located at the base of your neck. It is a very important gland that produces a hormone that helps regulate your entire bodys metabolism, temperature, heart rate, growth, and development.XResearch source The thyroid gland can be functionally underactive or overactive. The thyroid can be enlarged, have benign nodules and, more rarely, malignant nodules.
The Importance Of Basal Body Temperature
Low body temperature is not only an indication of a possible thyroid or adrenal dysfunction, but it can also create an environment for worsening problems. Our body temperature is critical for optimal immune function, circulation, enzyme activity and more .
A lower than normal body temperature creates an environment that is ripe for pathogens like bacteria and viruses. The reason we create a high temperature fever when we have a bacterial infection or a flu is that the high temperature is inhospitable for the bacteria and viruses and it activates powerful immune activities within the body.
Additionally, enzymes are temperature dependent and wont function well at lower than optimal temperature ranges. A low-body temp will reduce overall enzyme activity which slows the bodies intracellular metabolism and causes an inability to buffer oxidative stress effectively. It also leads to poor digestion and sluggish gut and liver metabolism and an inability to deactivate and excrete toxins from the body.
Recommended Reading: Apple Cider Vinegar Thyroid Nodules
What Is A T3 Test
T3 TestsT3 tests measure triiodothyronine levels in the blood. A Total T3 test measures the bound and free fractions of triiodothyronine. Hyperthyroid patients typically have an elevated Total T3 level. T3 tests can be used to support a diagnosis of hyperthyroidism and can determine the severity hyperthyroidism.
In some thyroid diseases, the proportions of T3 and T4 in the blood change and can provide diagnostic information. A pattern of increased T3 vs T4 is characteristic of Graves disease. On the other hand, medications like steroids and amiodarone, and severe illness can decrease the amount of thyroid hormone the body converts from T4 to T3 resulting in a lower proportion of T3.
T3 levels fall late in the course of hypothyroidism and therefore are not routinely used to evaluate patients with underactive or surgically absent thyroid glands.
Measurement of Free T3 is possible, but is often not reliable and therefore may not be helpful.
What Is Reverse T3
Reverse T3 is a biologically inactive form of T3. Normally, when T4 is converted to T3 in the body, a certain percentage of the T3 is in the form of RT3. When the body is under stress, such as during a serious illness, thyroid hormone levels may be outside of normal ranges even though there is no thyroid disease present. RT3 may be elevated in non-thyroidal conditions, particularly the stress of illness. It is generally recommended that thyroid testing be avoided in hospitalized patients or deferred until after a person has recovered from an acute illness. Use of the RT3 test remains controversial, and it is not widely requested.
You May Like: Collagen For Thyroid
What Happens After A Fine Needle Aspiration Biopsy
Most people will be able to resume their normal activities right away. You can remove your bandage within a few hours.
The site of the biopsy might be sore for a day or two after the procedure. You can take over-the-counter pain medicines if you need to. Follow any other specific instructions that your healthcare provider gives you.
It may take several days to get your test results from the pathology lab. Ask your healthcare provider when you can expect to get your results back.
If your thyroid nodule is not cancer, you might not need any further treatment. Your provider may want to monitor your nodule, though, and you might need another biopsy in the future. In some cases, your healthcare provider may offer thyroid hormone pills. These can sometimes decrease the likelihood of nodules growing back.
You will probably need surgical treatment if your nodule appears cancerous. Luckily, most thyroid cancers are curable.
Sometimes, the pathologist cannot determine for sure whether your nodule is cancer. In this case, your healthcare provider might recommend a repeat biopsy or surgery. Whatever your test results, you can work with your healthcare provider to develop the best possible treatment plan for you.
Things That Can Affect Your Thyroid Function Results
Fasting Generally, you dont need to fast before doing a thyroid function test. However, not fasting is sometimes linked to a lower TSH level. This means your results might not pick up on mild hypothyroidism where your TSH levels are only mildly elevated.
Medications Some medications can interfere with your results so its important to tell your doctor about any drugs you take.
Pregnancy Being pregnant can also influence your results. So if youre pregnant make sure to discuss this with your doctor.
You May Like: Can You Take Collagen Supplements With Levothyroxine
What Are Thyroid Function Tests
If your doctor suspects you are having problems with your thyroid, he or she may recommend a thyroid function test.
These simple blood tests are used to determine how well your thyroid gland is working based on your hormone levels.
There are four different types of thyroid function tests: T3, T3RU, T4 and TSH.
If your doctor is concerned about the levels of your hormones, broad screening tests, like the T4 or the TSH test will be ordered.
Further tests may be needed to help determine whats going on if the results of these tests come back abnormal.
Dont Miss: Does Removing Thyroid Cure Hashimotos
What Does The Test Result Mean
If the feedback system involving the thyroid gland is not functioning properly due to one of a variety of disorders, then increased or decreased amounts of thyroid hormones may result.
- When TSH levels are increased, the thyroid will make and release inappropriate amounts of T4 and T3 and you may experience symptoms associated with hyperthyroidism.
- If there is decreased production of thyroid hormones, you may have symptoms of hypothyroidism.
The test results alone are not diagnostic but will prompt your healthcare practitioner to perform additional testing to investigate the cause of the excess or deficiency and thyroid disorder. As examples, the most common cause of hyperthyroidism is Graves disease and the most common cause of hypothyroidism is Hashimoto thyroiditis.
The following table summarizes some examples of typical test results and their potential meaning.
|Note: Laboratory results must always be correlated with the clinical findings of the patient.|
|Hypothyroidism resulting from a problem with the hypothalamus or pituitary signals that govern the thyroid gland|
You May Like: Is Apple Cider Vinegar Good For Your Thyroid
What To Consider In Your Personal And Family Medical Histories
Its important to give your physician as many details as possible about your personal medical history, as well as family history . Be sure to discuss:
- Your general state of healthparticularly any changes you have noticed in your general overall health.
- Your familys health historyespecially if a close relative has been diagnosed with hypothyroidism .
- Whether youve ever had thyroid surgery, or radiation to your neck to treat cancer.
- Any medicines you may be taking that could cause hypothyroidism .
Physical ExaminationLooking for Signs of HypothyroidismYour physician will perform a thorough examination and look for physical signs of hypothyroidism, including:
- Evidence of dry skin
- Swelling around the eyes and legs
- Slower reflexes
- Slower heart rate
Blood Tests: Hypothyroidism can be detected by different blood tests.
- TSH Test. A thyroid-stimulating hormone or TSH is a blood test that measures the amount of T4 that the thyroid is being signaled to make. If you have an abnormally high level of TSH, it could mean you have hypothyroidism.
- T4 Test. The thyroid gland produces T4 . The free T4 and the free T4 index are blood tests that, in combination with a TSH test, can let your physician know how your thyroid is functioning.
Normal and Abnormal TSH Ranges
An easy way to remember how the thyroid works–think about supply and demand. As the T4 level falls, the TSH rises. As the T4 level rises, the TSH falls. However, not everyone with hypothyroidism has elevated levels of TSH.
Other Things That Interfere With Absorption
While I believe that coffee interference was my top problem with my thyroid medication absorption, I believe I had others, too one in particular.
First, let me tell you what other medicines, supplements, and minerals can interfere with your thyroid medication.
Any of these can prevent proper absorption:
- Very high fiber diet
- Weight Changes
So, your morning cup of Joe may not be the only thing interfering with your thyroid medication.
So, my coffee want my only issue. I had one more absorption issue to worry about.
Read Also: Hypothyroidism Double Chin
When To See Your Gp
Symptoms of an underactive thyroid are often similar to those of other conditions, and they usually develop slowly, so you may not notice them for years.
You should see your GP and ask to be tested for an underactive thyroid if you have symptoms including:
- being sensitive to the cold
- dry skin and hair
- muscle aches
The only accurate way of finding out whether you have a thyroid problem is to have a thyroid function test, where a sample of blood is tested to measure your hormone levels.
Read more about testing for an underactive thyroid
What Medications Can Affect The Thyroid Panel Tests
Many multivitamins, supplements , and over-the-counter and prescription medications may affect thyroid test results and their use should be discussed with your healthcare practitioner prior to testing. For example, biotin can interfere with some lab tests, so your healthcare practitioner may advise you to refrain from taking biotin or supplements that contain biotin for a few days before having blood drawn for a thyroid panel.
Read Also: Can You Take Collagen With Thyroid Medicine
Instructions For The Basal Body Temp
*If you are using an oral thermometer in the mouth for this, you must realize that the oral temp is typically about a ½ degree higher. So be sure to subtract ½ degree from your result to make it closer to your underarm temperature. If using the Galinstan or mercury thermometer in your mouthleave it in for 5 minutes.
What Other Tests May Be Ordered In Addition To A Thyroid Panel
Blood tests that may be performed in addition to a thyroid panel may include:
- Thyroid antibodies – to help diagnose autoimmune thyroid disease and distinguish it from other thyroid conditions
- Calcitonin – to help diagnose C-cell hyperplasia and medullary thyroid cancer
- Thyroglobulin – primarily to monitor treatment and recurrence of thyroid cancer
- Thyroxine-binding globulin – to evaluate patients with abnormal T4 and T3 levels
Don’t Miss: Does Apple Cider Vinegar Help Thyroid Problems
What Are Thyroid Hormones
The thyroid is a small gland that sits at the front of your neck. Itâs responsible for controlling many of the bodyâs key activities â such as metabolism. It does this by releasing specific hormones into the bloodstream.
A hormone is small chemical messenger that allows different parts of your body to âtalkâ with each other. The thyroid makes two kinds of hormones: thyroxine and triiodothyronine . These hormones circulate in your blood, allowing the thyroid gland to regulate many of the bodyâs important functions, such as:
- Metabolism â Thyroid hormones tell the body when to burn fat, which gives you more energy. Thyroid hormones can also trigger the production of glucose â a sugar formed from carbohydrates â to provide your body with more energy.
- Heart rate â Thyroid hormones can affect your resting heart rate .
- Internal body temperature â Thyroid hormones are involved in regulating your bodyâs internal temperature â so the thyroid gland acts a bit like a thermostat that helps make sure your body doesnât get too cool or too hot.
Whatâs more, thyroid hormones can contribute to more wakefulness and alertness because of how they affect the nervous system.
In short, your body requires the right balance of thyroid hormone levels in order to effectively carry out many of its functions.
Remember Certain Foods And Supplements Can Interfere With Synthroid
Foods containing soy and cottonseed meal can make Synthroid less effective. Walnuts, grapefruit juice, and dietary fiber can also make Synthroid less effective. If you eat any of these on a regular basis, check with your doctor. He or she may need to adjust your dose of Synthroid.
Some supplements and medications can also interfere with the way Synthroid works. To avoid this, you should take Synthroid 4 hours before or after taking:
- Iron supplements and multivitamins with iron
- Calcium supplements or multivitamins with calcium
You May Like: Is Apple Cider Vinegar Good For Your Thyroid
Is There Anything Else I Should Know
In the past, panels of tests were more common. More recently, however, the practice has been to order, where possible, one initial or screening test and then follow up with additional testing, if needed, to reduce the number of unnecessary tests. With thyroid testing, one strategy is to screen with a TSH test and then order additional tests if the results are abnormal or if clinical suspicions warrant.
Your thyroid hormone test results can be affected by:
- Increases, decreases, and changes in the proteins that bind T4 and T3
What Do My Thyroid Test Results Mean
The two most common types of thyroid function tests are the T4 and TSH test. Typically, these two tests are ordered together.
The T4 testmore commonly known as the thyroxine testis used to determine if your thyroid is overactive. If this is the case, you will be diagnosed with hyperthyroidism.
Symptoms of hyperthyroidism include unplanned weight loss, tremors, diarrhea and anxiety.
The TSH test will reveal how much thyroid-stimulating hormone is in your blood. Normal levels range from 0.4 to 4.0 milli-international units of hormone per liter of blood.
If youve been diagnosed with hyperthyroidism and your TSH levels are above 2.0 mIU/L, you are at a heightened risk of developing hypothyroidism, which can result in weight gain, fatigue, depression and weak hair and nails.
If your doctor believes you have hyperthyroidism, he or she may order a T3 test to check for levels of the hormone triiodothyronine.
This hormone level should be within 100-200 nanograms of hormone per deciliter of blood. If your levels are abnormally high, it is possible that you are suffering from an autoimmune disorder called Graves disease.
The final thyroid function test your doctor may order is the T3 resin uptake test. Also known as a T3RU, this blood test will measure the binding capacity of a hormone called thyroxin-binding globulin.
Your doctors office should reach out to you within a matter of days to walk you through the results of your thyroid test.
Don’t Miss: Is Apple Cider Vinegar Good For Your Thyroid