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Do You Have To Fast For Thyroid Panel

What Does The Test Result Mean

Do you have to Fasting for Thyroid Blood Tests? |Thyroid Series| Dr.Ravi Sankar | Hi9

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

Whats The Difference Between The Standard Thyroid Panel And The Thyroid Panel With Tsh

The Thyroid Panel with TSH includes all the tests from our standard Thyroid Panel, along with a TSH test. Thyroid stimulating hormone is often used as an initial thyroid test because it is an indirect indicator of thyroid hormone levels. Generally, the pituitary gland releases more TSH to stimulate thyroid hormone production, and less TSH when there are too many thyroid hormones. However, sometimes TSH levels may not rise or fall appropriatelylike if there is a problem with the pituitary gland. By measuring thyroid hormones and TSH, this test panel can provide a doctor or endocrinologist with more information about a potential imbalance.

What Does The Test Measure

The TSH test measures thyroid-stimulating hormone, which is a hormone that prompts the thyroid to produce other hormones. The thyroid is a butterfly-shaped gland in your neck that makes the hormones triiodothyronine and thyroxine . T3 and T4 control your metabolism, or how your body uses and stores energy.

Although TSH acts upon the thyroid gland by binding to the TSH receptor, it is made in the pituitary gland. The pituitary gland is sometimes called the master gland, because it produces many hormones that control the functions of other glands in the body. The pituitary gland is able to sense when your T3 and T4 hormone levels are too low or too high. In response, it will produce more or less TSH to stimulate your thyroid gland to produce the right amount of hormones.

If your thyroid is underactive, you may have high levels of TSH as your pituitary gland tries to stimulate the thyroid to produce more T3 and T4. If your thyroid is overactive, your TSH may be abnormally low because your pituitary gland stops making TSH when your thyroid hormone levels are too high.

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When Do I Need A Thyroid Test

One may need a thyroid test if you think you have symptoms of underactive or overactive thyroid gland. Having excessive thyroid hormones in your blood is called hyperthyroidism and insufficient thyroid hormones is known as hypothyroidism.

Symptoms of hypothyroidism include following:

  • Weight gain
  • Diarrhea

Are There Other Uses For The Measurement Of Total T4

Which Thyroid Test Should You Get?

In addition to being used for the diagnosis of hypothyroidism, total T4 can be used to monitor therapeutic levels of thyroid hormone supplementation if your dog requires thyroid hormone replacement therapy.

Additionally, in the very rare cases of suspected thyroid gland cancer, total T4 can be monitored to determine whether the cancerous tissue is producing excessive amounts of thyroid hormone.

Contributors: Krista Williams, BSc, DVM Kristiina Ruotsalo, DVM, DVSc, Dip ACVP Margo S. Tant BSc, DVM, DVSc

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How Is The Test Used

A thyroid panel may be used to evaluate thyroid function and/or help diagnose thyroid disorders.

Typically, the preferred initial test for thyroid disorders is a TSH test. If the TSH level is abnormal, it will usually be followed up with a test for free T4. Sometimes a total T3 or free T3 will also be performed. Often, the laboratory will do this follow-up testing automatically. This is known as reflex testing and it saves the healthcare practitioner time from having to wait for the results of the initial test and then requesting additional testing to confirm or clarify a diagnosis. Reflex tests are typically performed on the original sample that was submitted when the initial test was requested.

As an alternative, a thyroid panel may be requested by your healthcare practitioner. This means that all three tests will be performed at the same time to get a more complete initial picture of thyroid function.

What Do The Results Mean

High TSH levels can mean your thyroid is not making enough thyroid hormones, a condition called hypothyroidism. Low TSH levels can mean your thyroid is making too much of the hormones, a condition called hyperthyroidism. A TSH test does not explain why TSH levels are too high or too low. If your test results are abnormal, your health care provider will probably order additional tests to determine the cause of your thyroid problem. These tests may include:

  • T4 thyroid hormone tests

Learn more about laboratory tests, reference ranges, and understanding results.

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How Do You Know If A Thyroid Test Kit Is Reputable

First, its important that the test kit itself is certified by Clinical Laboratory Improvement Amendments , which ensures quality laboratory testing. Youll also want to check if they are certified by the College of American Pathologists , which ensures best practices regarding obtaining accuracy of test results and meeting other important required standards. According to Dr. Shah, The lab Paloma Health uses is a CLIA and CAP-certified lab, government-certified at the gold standard of the lab industry. The labs are tested versus commercially available labs to be equivalent in their results.The same goes for other test kits made by other companies: Other services who use CLIA- and CAP-certified labs will also provide accurate readings, she says.Dr. Shapiro also recommends asking your endocrinologist or healthcare provider if they can recommend a reputable thyroid test kit.The good news is that at-home test kits, when bought by a reputable provider, are generally very reliable. According to a study in the Journal of Medical Screening, they offer accurate and inexpensive testing.

What Should Be Tested

When to Test Your Thyroid

A full thyroid panel is required to obtain the most comprehensive and accurate look at how youre doing, as TSH alone and even TSH and Free T4 test without the other components of the thyroid panel, dont give the full picture.

Free T3 and Thyroid Antibodies TpoAB and TgAB are important to monitor too. Many thyroid patients find that whilst their TSH is OK, their Free T3 and Free T4 are not optimal and so they still feel unwell. If your doctor wont order the full thyroid panel, do know that it is relatively inexpensive and simple to order these tests yourself. UK thyroid patients can order them from here and a worldwide link can be seen here.

TSH serves as an average read out over the previous four to six weeks of your thyroid levels but doesnt give the most comprehensive view.

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How Much Does The Test Cost

The cost of a TSH test will vary depending upon factors such as where it is performed and whether or not you have insurance coverage. Insurance will usually cover the cost of TSH testing if your doctor orders it to diagnose or treat a medical condition. You can check with your doctor, the lab, or your insurance company to learn more about the cost and what, if any, out-of-pocket costs you may be responsible for.

Recommendations For Those On T4

T4-only medication has a five- to nine-day half-life, which means that once you have become stable on the current dosage, it can take up to nine days for 50 percent of the dose to clear the body. T4 has a slow and steady release and wont produce many fluctuations that can make a person feel like theyre on a thyroid roller coaster.

Whether you take your T4 medication right before your lab tests or havent taken it for up to 48 hours, your TSH value should be the same. Thus, you will get an accurate representation of your TSH value whether or not you take your T4 medication before a lab test.

The same goes for free T3 levels when you take a T4 medication. The free T3 level will also be relatively constant.

Levels of free T4, however, will peak two hours after your T4 medication is taken.

So lets say you take your T4 medication at 8 am and have your blood test at 10 am your thyroid labs may show that your T4 is falsely elevated. This may result in your doctor lowering your medication, when in reality, your T4 levels may be within range for the rest of the day, with the exception of that two-hour, post-dose peak.

In most cases, taking a T4 medication the morning before your lab test will not be an issue, as most doctors adjust the dosages according to the TSH, which stays stable after T4 dosing.

However, to get a reading of your T4 levels that is reflective of most of the day, you would want to postpone your T4 medication until after the lab test.

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Does Being Ill Affect The Test

Being unwell could affect test results temporarily. Sometimes, infections or a bout of an inflammatory condition can alter results until the illness resolves, so if you receive an unexpected result when unwell, it is probably wise to retest after youve recovered to rule it out.

Also, as diarrhoea can interfere with the absorption of your thyroid medication, this could affect your thyroid hormone levels and any testing.

Thyroid Test Kit Fast Facts

  • At-home thyroid test kits are considered very accurate, but you should make sure you are purchasing a CLIA- and CAP-certified test through a reputable provider.
  • Popular thyroid kits offer testing for several biomarkers, including free thyroxine , free triiodothyronine , thyroid stimulating hormone , and thyroid peroxidase antibodies , in addition to others.
  • At-home test kits are an inexpensive and easy way to learn more about your thyroid health or monitor your thyroid health without going to see a doctor for regular testing.
  • Most test kits will provide your test results along with a basic analysis of results, but its important to see your healthcare provider for in-depth analysis, diagnosis, and proper treatment.
  • You should never self-medicate or change a prescription or medical plan based off of at-home test kit results without speaking with your doctor first.

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The Power Of Fasting And Thyroid Health

When it comes to battling many of todays health issues, the entire premise of modern medicine is incorrect. In the past, diseases like cholera and smallpox could be treated with medicines like penicillin and other antibiotics, but times have changed. Yellow fever has been replaced by heart disease, Type II Diabetes, thyroid issues and other diseases that are more dietary in nature. In other words, instead of looking for the latest drug, the best form of treatment is to fix cellular dysfunction and incorporate ancient healing strategies such as fasting.

While modern medicine hasnt embraced fasting as a viable health option , the practice has been around since the beginning of time. Fasting is known to rejuvenate and revitalize the body. Even animals will fast when they are stressed, ill or feel unease. The refusal to eat is a form of self-preservation to remove waste products and promote healing of the body. Fasting and thyroid health go hand in hand: fasting makes us more responsive to our hormones, thus improving thyroid function.

Today, the philosophy on eating is the polar opposite of the ancient practice of fasting: We are now in a constantly fed state. We have gone from an average of eating three meals a to eating five to six meals a day: breakfast, a snack, lunch, snack, dinner, and another snack. This change in eating habits has had a detrimental effect on our health.

Preparing For A Thyroid Blood Test Will Include The Following

Some researches, however, claim that T3, T4 and TSH levels did not show any significant difference in fasting and non-fasting conditions in the same patient. For this reason, fasting for 8-12 hours is advised. You will be asked to report to the laboratory in the morning.

If you go for a thyroid blood test routinely or if you have been on thyroid treatment, it is usually advisable to go for the test at the same time and in the same manner, that is, fasting or non-fasting.

Drawing blood takes less than 5 minutes. You can resume your regular work immediately.

There are no specific risks for a thyroid blood test. You may notice slight bruising at the site of the punctured vein. This goes away in a day or so without doing much to it. You can even apply ice packs if the bruise hurts too much. Contact your doctor immediately if the punctured vein site becomes red and swollen.

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How Does A Blood Test For Hypothyroidism Work

How to test for hypothyroidism?

Itâs important to note that there is no hypothyroidism test that can check thyroid hormones andâbased only on those test resultsâconclusively determine if someone has hypothyroidism. Thatâs because both thyroid hormone testing and a physicianâs evaluation of symptoms and medical history is required for a diagnosis.

A blood test for hypothyroidism is based on your levels of thyroid-stimulating hormone and the thyroid hormones T3 and T4. Because TSH signals the thyroid gland to produce more thyroid hormones, unusually high levels of TSH can mean that your thyroid isnât making enough hormones.

A thyroid lab test might also measure T3 and T4 to reveal just how low your thyroid hormone levels are, which can help your healthcare provider decide on a treatment strategy.

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Fasting And Thyroid Test Results

Fasting & Your Thyroid-Q & A

Studies have shown that time of day and fasting can affect your results. If you test in the early morning after overnight fasting, the results may show higher levels. This is compared to tests done later in the day with no fasting.

That can be a problem if you have subclinical hypothyroidism. This is when you have a mildly elevated TSH and normal free T4, but no symptoms. Free T4 is the active form of T4.

This condition is diagnosed and monitored based solely on TSH. T4 and T3 levels are usually normal.

If you get your blood test in the afternoon when you have not been fasting, your TSH levels will be lower. Because of this, your subclinical hypothyroidism may be missed.

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What Does Your Thyroid Gland Do

Your thyroid gland is a gland found at the front of your neck, just below your Adams apple. Your thyroid gland produces hormones that play a key role in regulating your metabolism and affects things like your heart rate, body temperature, and breathing. These hormones are:

  • thyroxine

The levels of these hormones are controlled by thyrotropin-releasing hormone and thyroid-stimulating hormone .

About Our Thyroid Panel With Tsh

Note: Fasting is not required for this test.

The Thyroid Panel with TSH is a group of blood tests that helps evaluate thyroid gland function and can help diagnose thyroid disorders. This group of tests measures the amount of thyroid hormones in the blood. Thyroid hormones are chemical substances that are important to regulating metabolism, or how the body uses energy.

The Thyroid Panel with TSH includes:

  • T4 The total amount of T4, a hormone produced by the thyroid, in the blood.
  • T3 uptakeTriiodothyronine, or T3, is another hormone produced by the thyroid. Thyroid hormones exist in two forms: either protein-bound or free . T3 uptake helps estimate the amount of TBG in the blood and is used along with Total T4 results to calculate T7.
  • T7 Used to estimate free T4.
  • TSH A hormone produced by the pituitary gland to regulate the release of thyroid hormones when T3 and T4 levels are too high or low.

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Where To Get A Thyroid Function Test

NHS thyroid function test The NHS offer blood tests which can be done at your GPs or a local hospital. A trained nurse or doctor will take your blood, usually a venous sample.

Home thyroid function test Its possible to order a home thyroid function test kit online and do it yourself. For this test, youll use a lancet to collect a finger-prick blood sample. Your results will be reviewed by a GP and are available for you to view online.

Symptoms That Might Require A Fasting Lab Test


You may have nonspecific symptoms that are hard to diagnose. Or, you may have the following symptoms that could prompt your doctor to order a fasting lab test:

  • Excessive urination and thirst could indicate diabetes.
  • Swollen feet and ankles could indicate kidney disease.
  • A high blood pressure reading could indicate high cholesterol.
  • A yellowish tint to your skin and eyes may indicate a liver condition.
  • Fatigue and an irregular heartbeat could indicate an electrolyte imbalance.
  • Pale skin and leg cramps could indicate anemia or a vitamin B12 deficiency.

Many other symptoms could make you need a fasting lab test. Your doctor might order a fasting lab test to rule out some of these conditions.

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