When Abnormal Thyroid Function Tests Are Not Due To Thyroid Disease
While blood tests to measure thyroid hormones and thyroid stimulating hormone are widely available, it is important to remember that no all tests are useful in all circumstances and many factors including medications, supplements, and non-thyroid medical conditions can affect thyroid test results. An endocrinologist can help you make sense of thyroid test results when there is a discrepancy between your results and how you feel. A good first step is often to repeat the test and ensure there are no medications that might interfere with the test results. Below are some common reasons for mismatch between thyroid tests and thyroid disease.
Non-thyroidal illness Significant illness, such as an infection, cancer, heart failure, or kidney disease, or recent recovery from an illness can cause changes transient changes in the TSH. Fasting or starvation can also cause a low TSH. An endocrinologist can help to interpret changes in thyroid function tests in these circumstances to distinguish non-thyroid illness from true thyroid dysfunction.
Test interference Biotin, a common supplement for hair and nail growth, interferes with many thyroid function tests and can lead to inaccurate results. Endocrinologists recommend stopping biotin supplements for 3 days before having a blood test for thyroid function.
What More Should I Know About Thyroid Tests
Thyroid hormone levels change during pregnancy and due to certain medical conditions. They also differ concerning the age and gender of an individual. Your healthcare provider will help monitor and assess thyroid levels. They will guide you on ways to balance these hormones and help maintain normal ranges.
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What Is A Normal Thyroid Level
Tests often used to assess thyroid hormone status include TSH and FT4 tests. The normal value for a laboratory test is determined by measuring the hormone in a large population of healthy individuals and finding the normal reference range. Normal ranges for thyroid tests may vary slightly among different laboratories, and typical ranges for common tests are given below.
TSH normal values are 0.5 to 5.0 mIU/L. Pregnancy, a history of thyroid cancer, history of pituitary gland disease, and older age are some situations when TSH is optimally maintained in different range as guided by an endocrinologist.
FT4 normal values are 0.7 to 1.9ng/dL. Individuals taking medications that modify thyroid hormone metabolism and those with a history of thyroid cancer or pituitary disease may be optimally managed with a different normal FT4 range.
Total T4 and Total T3 levels measure bound and free thyroid hormone in the blood. These levels are influenced by many factors that affect protein levels in the body, including medications, sex hormones, and liver disease. A normal Total T4 level in adults ranges from 5.0 to 12.0g/dL. A normal Total T3 level in adults ranges from 80-220 ng/dL.
Free T3 assays are often unreliable and not routinely used to assess thyroid function.
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Thyroid Questions Let Us Answer Them
Now you know all about normal thyroid hormone levels and when you need to seek treatment.
PrimeHealth is devoted to answering peoples questions about medical conditions and autoimmune diseases, like Hashimotos thyroiditis. We believe its important to make patients feel heard and educate them on what is going on in their bodies.
Did you know? A lot of peoples hypothyroidism can be permanently cured. Even what conventional doctors might call permanent hypothyroidism may be treatable. Our patients prove it.
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What Do The Results Mean
Your TSH test results can tell you if your thyroid is making too much or too little thyroid. But the test can’t explain why your TSH levels may be too high or too low.
If your test results aren’t normal, your provider will probably order other thyroid blood tests to find out what’s causing your thyroid problem. These blood tests may include:
- Thyroid antibodies test to help diagnose an autoimmune thyroid disorder, such as:
- Graves’ disease, the most common cause of hyperthyroidism
- Hashimoto’s disease, that the most common cause of hypothyroidism
In certain cases, an abnormal TSH result may be a sign of a pituitary gland problem, but this doesn’t happen often.
Learn more about laboratory tests, reference ranges, and understanding results.
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Connection To Thyroid Peroxidase Antibody
Thyroid peroxidase antibody is very similar to TgAb: it is also an antibody that mistakenly attacks the thyroid gland. While TgAb targets thyroglobulin, TPOAb targets an important thyroid enzyme called thyroid peroxidase. TPOAb can increase oxidative stress and may damage the thyroid .
The TBOAb test is also sometimes called the Antithyroid Microsomal Antibody Test .
The same conditions that cause TgAb to increase usually also raise TPOAb. In fact, TPOAb may be a better indicator of autoimmune thyroid disorders than TgAb .
About 90-95% of people with autoimmune thyroid disorders have detectable TPO antibodies, while only 70-80% of them have detectable thyroglobulin antibodies. Therefore, your test results may come back as normal TgAb and detectable TPOAb even if you have autoimmune thyroid issues .
TPOAb assays vary in sensitivity. Older assays may not detect TPO antibody levels more sensitive assays would. If your TPOAb came back normal and your TgAb high, you should probably repeat the TPO test with a more sensitive assay .
People without thyroid problems may also test positive for TPOAb. According to some estimates, about 10 to 15% of the general population produce TPOAb .
Another big difference between these two types of antibodies is that TPOAb does not interfere with thyroglobulin tests like TgAb does. This means a TPOAb test would not be helpful for determining thyroglobulin levels .
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What Is It Used For
If you take prescription thyroid hormone medicine because of hypothyroidism or because you had your thyroid removed, you’ll have regular TSH tests to check your thyroid hormone levels. TSH tests are also used to monitor your thyroid hormone levels after treatment for hyperthyroidism.
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What Is Thyroid Stimulating Hormone
Thyroid-stimulating hormone is a hormone that stimulates the thyroid gland to produce thyroid hormones. The pituitary gland secretes more TSH when blood levels of T4 and T3 fall below normal, and reduces the TSH secretion when T4 and T3 levels rise. The hypothalamus region of the brain regulates pituitary gland activity.
Other Types Of Thyroid Tests
Your provider may also perform a physical exam of the thyroid by feeling your next. According to Dr. Kanji, this might be looking at the front of your neck and from behind you to see if there are any concerns such as an enlarged thyroid gland or nodules. If there is swelling, your provider will want to determine if its present on one or both sides of the neck.
If a physical exam shows concerning symptoms, a thyroid ultrasound can confirm if nodules or goiter is present. Goiter can also be the result of thyroid tumors, which are typically benign. It uses high-frequency sound waves to make an image of the thyroid, and can help diagnose signs of thyroid cancer.
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Testing For T3 T4 And Tsh Levels
Here at PrimeHealth, we administer a more robust set of thyroid function tests than most of the medical community. Many conventional primary care doctors and endocrinologists tend to only focus on TSH levels.
Additionally, its important to take into account optimal levels versus reference range levels. Thats why we administer a more thorough panel of tests.
Also, keep in mind that if youre taking thyroid medications, the time from your last dose will change the way we interpret your lab values. Your provider may have you test your thyroid panel before or after taking your medication in the morning to assess your thyroid levels at various times during the day.
We believe the most accurate and thorough way to test for thyroid function is to measure:
- Anti-thyroglobulin and anti-TPO antibodies
- Thyroid-binding globulin
Important: Make sure youre not taking biotin when testing for thyroid hormone levels. This popular supplement for hair and nail growth can interfere with test results.
What are normal TSH test results? The normal range of thyroid test results is 0.5-5.0 mIU/L, but we recommend TSH levels stay under 2.5 mIU/L. If your TSH level sits outside this reference range, you probably suffer from a thyroid disorder that needs to be treated.
Tsh Normal Levels Chart By Age
Normal TSH levels for childrenFor premature birth is 0.7 27 mIU/LNormal TSH level for age 1 day 1 week is 1.0 40.0 mIU/mLNormal TSH level for age 2 weeks 1 month is 1.7 9.1 mIU/mLNormal TSH level for age 2 months 1 year is 0.8 6.4 mIU/mLNormal TSH level for age 2 years 5 years is 0.7 5.4 mIU/mLNormal TSH level for age 6 years 10 years is 0.53 5.3 mIU/mLNormal TSH level for age 11 years 18 years is 0.5 5.0 mIU/mLChart of normal TSH levels for adult man and adult non-pregnant womanAge 21 54 years is 0.4 4.2 mIU/LAge 55 87 years is 0.5 8.9 mIU/LChart of TSH normal levels during pregnancyFirst trimester normal TSH is 0.1 2.5 mIU/LSecond trimester normal TSH is 0.2 3.0 mIU/LThird trimester normal level of TSH is 0.3 3.0 mIU/LTSH is the most well-studied marker for thyroid function evaluation.TSH is considered the most sensitive and accurate indicator of thyroid function by most endocrinologists and other doctors.TSH normal reference ranges are from the American Thyroid Association and published in the journal Thyroid.Also, some thyroid testing kits may recommend another normal reference.After presenting what is the normal range for TSH blood test, a new publication about TSH results comes soon. SUBSCRIBE to get free explanation of your results,
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Testing Your Thyroid Levels
According to the American Thyroid Association, there isnt one test for every situation in fact, there are several kinds of thyroid tests. But if you are concerned about thyroid issues, or if your hormones are imbalanced, your doctor may provide an initial TSH level blood test. This is because the TSH level can serve as a tip-off to other, more specific issues.
Whats a normal TSH level? Most lab companies have a wide reference as it relates to TSH levels , Dr. Rice says. So, if your results are somewhere between 0.4-4.0, youd be in the normal range. However, there is research that suggests that the reference range for TSH should be narrowed to 0.4 to 2.5, says Dr. Rice, which means that the normal range could be even smaller than some healthcare providers might think.
Generally, healthy TSH levels are an indicator the whole system is working well, but thats an oversimplification at best. A normal T3 level might be somewhere between 100 to 200 nanograms per deciliter , while a normal T4 level falls between 5.0 to 12.0 micrograms per deciliter . Free T4, which tests for the amount of T4 that is available in the body, should range between 0.8 to 1.8 nanograms per deciliter .
Understanding The Two Main Thyroid Hormones: T3 & T4
The thyroid gland takes its direction from both the hypothalamus and the pituitary gland, a pea-sized gland at the base of your skull. In a complex dance, the hypothalamus releases something called thyrotropin-releasing hormone, which then triggers the pituitary gland to produce something called the thyroid stimulating hormone . The TSH is then what helps your thyroid gland release T4 and T3. Without TSH, the system would fail.
Thyroxine is responsible for your metabolism, mood, and body temperature, among other things. T3, too, is made in the thyroid gland, and it can also be made in other tissues within the body by converting T4 into T3. This hormone is at the center of your digestive and metabolic function, and it also oversees bone health.
So, if your T3 and T4 levels are too low, the pituitary gland will release more TSH. If theyre too high, the gland will release less TSHbut this give and take system only works if everything is functioning properly.
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What Is The Reason For High Tsh Levels
High levels typically indicates an underactive thyroid gland, which produces too little thyroid hormone. This is known medically as hypothyroidism.
Common causes of hypothyroidism include an autoimmune disease , radiation treatment, or surgical removal of the thyroid gland.
Replacing thyroid hormone and altering your diet are crucial for the safe and effective treatment of an underactive thyroid.
Summary: High TSH levels for the average adult are 4.2 mIU/L and over. This reading typically indicates an underactive thyroid.
Symptoms Of A Thyroid Problem
The TSH test helps doctors diagnose common thyroid disorders, such as hyperthyroidism and hypothyroidism.
The signs and symptoms of hyperthyroidism, in which the thyroid overproduces hormones, include:
- rapid or irregular heart rate
A TSH test may also help indicate other types of thyroid problem, such as:
- Gravesâ disease, which causes greater activity of the thyroid
- Hashimotoâs thyroiditis, an autoimmune condition where the body attacks the thyroid
- thyroid nodules, which are lumps on the thyroid that contribute to an overactive thyroid
- inflammation of the thyroid gland, called thyroiditis
- postpartum thyroiditis, which is temporary thyroiditis following pregnancy
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How Do You Test Tsh Levels
Healthcare providers test TSH levels using a blood test. They take a sample of blood from a vein in your arm and send the sample to a laboratory for testing. You usually dont need to do anything special to prepare for a TSH blood test.
A TSH blood test is usually the first test providers order if youre experiencing symptoms related to thyroid issues.
What Is A T4 Test
T4 Tests A Total T4 test measures the bound and free thyroxine hormone in the blood. A Free T4 measures what is not bound and able to freely enter and affect the body tissues.
What does it mean if T4 levels are abnormal? Importantly, Total T4 levels are affected by medications and medical conditions that change thyroid hormone binding proteins. Estrogen, oral contraceptive pills, pregnancy, liver disease, and hepatitis C virus infection are common causes of increased thyroid hormone binding proteins and will result in a high Total T4. Testosterone or androgens and anabolic steroids are common causes of thyroid hormone binding proteins and will result in a low Total T4.
In some circumstances, like pregnancy, a person may have normal thyroid function but Total T4 levels outside of the normal reference range. Tests measuring free T4 either a free T4 or free T4 index may more accurately reflect how the thyroid gland is functioning in these circumstances. An endocrinologist can determine when thyroid disease is present in the context of abnormal thyroid binding proteins.
What Are Normal Tsh Levels
Normal levels of TSH vary based on your age. In general, normal ranges of TSH for healthy people who arent pregnant include:
- Infants up to 5 days old: 0.7 15.2 micro-international units per milliliter .
- Infants 6 to 90 days old: 0.72 11.0 uIU/mL.
- Babies 4 to 12 months old: 0.73 8.35 uIU/mL.
- Children 1 to 6 years old: 0.7 5.97 uIU/mL.
- Children 7 to 11 years old: 0.6 4.84 uIU/mL.
- People 12 to 20 years old: 0.51 4.3 uIU/mL.
- Adults 21 to 99 years old: 0.27 4.2 uIU/mL.
Normal value ranges for TSH may vary slightly among different laboratories. Be sure to check your lab reports reference range on your results. If you have any questions about your results, ask your healthcare provider.
Supporting A Healthy Thyroid
Now that you have a basic overview of thyroid function, you may be wondering if there are ways to support your thyroid healthin addition to medication. This is important because sometimes it can take a while before medication can correct hormone imbalance. In this case, the next best thing you can do is adjust your lifestyle habits.
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How Important Is It For Women To Maintain Normal Thyroid Levels
Women should aim to maintain normal thyroid levels due to number of reasons, and these include:
- Stabilizing the bodys metabolism
- Improving the utilization of carbohydrates, fats, proteins and cholesterol
- Stimulating the brain, nerves and heart muscles
- Optimum fetal growth during pregnancy
Normal thyroid levels in women during pregnancy are especially important to avoid complications both to the mother and child due to thyroid problems.
When Normal Tsh Does Not Reflect Euthyroidism
As mentioned earlier, while there may be some controversy about where the normal range for TSH should lie,2,3 current clinical guidelines are clear that a TSH in the upper normal range does not reflect hypothyroidism.4,5 The potential unreliability of a normal TSH to accurately reflect true thyroid status is an ever-increasing question raised by patients who suffer from a myriad of non-specific complaints. As mentioned previously, many times these complaints are extremely prevalent: overweight , obesity , depression , hair loss , and fatigue . The quest for a reason and eventual relief of these burdensome symptoms is understandable and, as such, a normal TSH result may lead to patient dissatisfaction and mistrust of their physician, whom they see as relying more on a biochemical test than their symptoms. Indeed, much of the print and internet-based literature fosters this mistrust of standard biochemical testing and provider reliance on such tests. An understanding of the actual prevalence for a truly unreliable TSH is, therefore, extremely helpful for primary providers as they discuss a normal TSH value with a sometimes skeptical patient.
Hypothalamic and/or Pituitary Disease
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