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Do You Need To Fast For A Thyroid Blood Test

What You Need To Know About Doing Thyroid Blood Tests

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

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Originally published on 30th May 2017

Common questions about thyroid blood tests for those with medical conditions such as a thyroid disorder include:

  • Do I take my thyroid medication as normal before the blood draw?
  • Do you need to fast for thyroid blood work?
  • How often should it be done?
  • Does it need to be in the morning?
  • Can it be done in the afternoon?
  • Is fasting required for a TSH test?
  • What should be tested?

Probably the most important thing to be aware of as someone with a thyroid condition, is whether you should take your thyroid medication before or after having any testing done.

Thoughts On What You Need To Know About Doing Thyroid Blood Tests

  • Solsays:

    Sad stories. Really, does the medical industry stand to gain by actually healing and curing people-by treating them appropriately so they function well? No. And so few people see this. They stand to lose immense amounts of money and power if we get well, so talk about a conflict of interest! Im still researching, but my mind really just wont work any longer to absorb the information. Ive been fighting the thyroid battle for decades. I had to pitch a fit in a doctors office just to get her to consider my thyroid when all she wanted to do was get me to exercise and see a counselor. They love referring you to counselors when you have thyroid related depression. Finally my doc found a lump on my thyroid that was precancerous. Over half my thyroid was removed and Ive had ups and downs since, but now its just going downhill and I dont have the presence of mind to fight it anymore. You shouldnt have to do all your own research, work to get a doctor to even listen to you, and still go around undertreated, ignored and mistreated while these quacks still get paid. What profession can completely fail you or make you worse, and still get paid? The medical profession, of course! Hoping all the best for you out there. God bless.

  • When To Take Thyroid Medications To Get Accurate Lab Results

    • TSH– This is a pituitary hormone that responds to low/high amounts of circulating thyroid hormone. In advanced cases of Hashimoto’s and primary hypothyroidism, this lab test will be elevated. In the case of Graves’ disease the TSH will be low. People with Hashimoto’s and central hypothyroidism may have a normal reading on this test.
    • Free T3 & Free T4-These tests measure the levels of active thyroid hormone circulating in the body. When these levels are low, but your TSH tests in the normal range, this may lead your physician to suspect a rare type of hypothyroidism, known as central hypothyroidism.

    Also Check: Subacute Lymphocytic Thyroiditis

    Why Do Some Blood Tests Require Fasting

    Certain blood tests require you to fast for 8-12 hours. The reason for asking you to fast is because when eat or drink beverages, certain nutrients, substances or vitamins enter into the bloodstream and can be responsible for giving a wrong result. Fasting before these advised blood tests ensures more accurate results.

    Certain blood tests require you to not even drink water. Otherwise, drinking normal water will keep you hydrated and prevent your veins from collapsing, so drawing blood becomes easier since your veins are visible.

    Avoid food, alcohol, soda or aerated drinks, tea, coffee, chewing gums and even exercising while fasting.

    You need to consult your physician if you can take your regular dose of medications during fasting or adjust the dose timings for the purpose of fasting. This is because certain drugs can alter test results.

    Are There Any Specific Tests For Hypothyroidism

    How to Properly Test Thyroid Function with Labs ...

    Thyroxine is the primary hormone produced by the thyroid gland in response to stimulation by the pituitary gland.

    A ‘feedback system’ exists between the thyroid gland and the pituitary gland. When T4 concentrations in the blood are low, the pituitary sends a signal to the thyroid gland using thyroid stimulating hormone , prompting the thyroid gland to produce more T4. When T4 levels in the circulation are adequate, the pituitary decreases its production of TSH, thereby reducing the production of T4.

    “If the total T4 concentration is well within the normal range, then your dog is not hypothyroid.”

    Total T4 . T4 circulates in the blood in two forms one form of the hormone is bound, or attached to proteins in the blood, while the other form circulates freely within the blood stream. Total T4 measures both forms of the hormone in a blood sample. If the total T4 concentration is well within the normal range, then your dog is not hypothyroid. If the total T4 concentration is at the low end or below the normal range, and your dog has supportive clinical signs, then hypothyroidism is likely. Unfortunately, there are conditions other than hypothyroidism that may cause the total T4 value to be reduced. These conditions include the presence of another illness or the administration of some drugs, such as anti-inflammatory medications. Your veterinarian may be able to measure total T4 levels in the veterinary office.

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    When Should I Get A Tsh Test

    TSH is often the first test doctors order when they suspect a patient has a thyroid disorder. Both hypothyroidism and hyperthyroidism are common disorders. All patients with symptoms of these thyroid disorders should have their TSH checked.

    If you are having symptoms of these disorders, your doctor may order a TSH or a thyroid panel test. Symptoms of hypothyroidism include:

    • Fatigue
    • Rapid or irregular heartbeat
    • Loose, frequent bowel movements

    TSH is also used to evaluate patients who are suspected to have other thyroid disorders, such as goiter, thyroid nodule, thyroid cancer, Graves disease, or Hashimotos thyroiditis. These disorders can cause hypothyroidism or hyperthyroidism.

    Screening with TSH for hypothyroidism in adults is controversial. Screening means testing in the absence of symptoms. It is most beneficial when early detection and treatment of disease helps people avoid subsequent medical problems. Some organizations, such as the American Association of Clinical Endocrinology, the American Thyroid Association, and the Endocrine Society, favor routine screening for thyroid problems in adults without symptoms.

    Because thyroid disorders can complicate pregnancy, screening with a TSH test during pregnancy is recommended for some women. Pregnant women without symptoms of thyroid problems may be screened if they:

    Best For Specialized Care

    Paloma Health

    Paloma Health is a telemedicine company with providers who specialize in thyroid disorders. The company only does thyroid testing. Their main goal is to be a one-stop-shop for all aspects of thyroid health.

    In this way, Paloma stands out from their competitors with a more holistic approach to care. They offer nutritional consults and health coaching, and one doctor is assigned to you throughout all your testing. This whole-body approach offers more than just the usual thyroid testing. Their additional antibody tests can detect Hashimotos thyroiditis and other thyroid disorders.

    You have the options to have TSH and free T4 levels tested, but the thyroid panel also includes testing of anti-TPO antibodies and free T3 levels.

    Youre provided a lancet to take a finger prick. This sample will be sent back in the provided biohazard bag, which is placed in the original box. A return envelope is provided for this. While results are read by healthcare professionals, for a separate fee, they can provide information about your results, as well as a treatment plan. Results are returned in 7 days.

    Cost: $99 for the thyroid test kit, additional costs for medications, and coaching and treatment plans

    Coverage: Consultations are covered by insurance. If Paloma isnt in-network, you can submit for reimbursement. Check with your insurance company to find out if they will cover at-home test kits.

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    Do You Follow These Tips When You Have Blood Drawn

    See also:

    The book Be Your Own Thyroid Advocate: When Youre Sick and Tired of Being Sick and Tired, which builds on this article in detail and explains how to thrive with thyroid disease.

    You can click on the hyperlinks in the above article to learn more and see references to information given, as well as the below links.

    Adult Hypothyroidism

    If you found this article beneficial, please take a moment to share it so we can help others get better with hypothyroidism and Hashimoto’s, whilst also raising awareness.

    Does Menstruation Affect Testing

    Can Keto & Fasting Heal Your Thyroid Condition?

    Generally, being on your period when having a thyroid test conducted isnt known to cause any issues or affect results, but if youre feeling particularly unwell from your period then you may wish to have blood drawn when you feel better. Especially if you already lose a lot of blood with menstruation. Heavy periods can be a symptom of hypothyroidism.

    Read Also: Starting Thyroid Medication

    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

    What Happens If You Dont Fast Before Blood Test

    Not fasting for a blood test will yield inaccurate results. As mentioned above, as the food is digested and metabolized, the nutrients which enter the bloodstream can interfere with test results.

    If you happen to accidentally eat or drink something before a blood test, make sure to inform your clinician about it. In this case, both the clinician makes a note of it and test results are analyzed accordingly or you for better results, an appointment for the blood tests may need to be rescheduled.

    Also Check: Is Fasting Required For T3 T4 Tsh Test

    What Are Thyroid Blood Tests And Why Are They Taken

    Thyroid blood tests are used to tell if your thyroid gland is functioning properly by measuring the amount of thyroid hormones in your blood. They are done by withdrawing blood from a vein in your arm. These blood tests help to diagnose thyroid diseases.

    The thyroid is a butterfly-shaped gland located in the front part of your neck. Its job is to produce thyroid hormones, which travel through your bloodstream and regulate many aspects of your bodys metabolism, including temperature, weight, and energy.

    Thyroid blood tests show if you have:

    • Hyperthyroidism: Overactive thyroid producing more thyroid hormones than your body needs. Hyperthyroidism speeds up your metabolism, which can cause weight loss, rapid heartbeat, insomnia, puffiness around the eyes, anxiety and other symptoms. The most common cause of hyperthyroidism is Graves disease.
    • Hypothyroidism: Underactive thyroid producing too few thyroid hormones. Hypothyroidism slows down your metabolism, which can cause weight gain, menstrual irregularity, dry and puffy skin, fatigue and other symptoms. The most common cause of hypothyroidism is Hashimotos disease.

    Thyroid blood tests are used to diagnose thyroid disorders associated with hyper- or hypothyroidism. These include:

    Can I Take Thyroid Tests During Pregnancy

    Do you really need to fast before a blood test?

    Yes, you can if need be.In fact,it is not uncommon to have thyroid changes during pregnancy. While overactive thyroid affects about one in every 500 pregnancies, underactive thyroid happens in around one in every 250 pregnancies. If you have a pre-existing thyroid condition or develop a thyroid condition during pregnancy, your doctor will monitor your condition and ask for blood tests too. Most likely, your thyroid hormone levels will be checked every 4 to 6 weeks during the first half of your conception, and at least once after 30 weeks.

    A thyroid panel test can help identify various conditions including hypothyroidism, hyperthyroidism, Graves disease, and thyroid cancer. For all your lab test related needs, visit Metropolis.


    Recommended Reading: Levothyroxine Dosage Guidelines

    Like Armour Naturthroid Westhroid Wp Thyroid Compounded T4 And T3

    This is where we see the hugest difference in the timing of your tests for accurate results. If you were to take your thyroid medication within 5 hours of getting your thyroid function tests done, your lab results may show that you are overdosed, even when you may be accurately dosed, or they may show your labs to be within normal limits, when you may actually be under-dosed.

    What happens is that the TSH is immediately affected by the T3 in the medication. It starts to drop immediately, and drops for 5 hours after taking the dose of medication. Then, it begins to rise, and reaches a stable point about 13 hours after taking the medication. This can vary in people, but the cited research study found that this is what can be expected in most people.

    T3, being the active form of the thyroid hormone, acts differently than T4 in that it has a relatively short half-life. Within 18 hours to 3 days, depending on the person, half of the T3 hormone is left compared to 9 days for T4. Therefore, levels of T3 can fluctuate during the day, in some rapidly declining within the day.

    When you take T3 in a medication, the free T3 levels on a blood test are affected immediately by increasing. The peak is about 4 hours after taking the medication. Then it starts the decline.

    Thus, it is usually best to postpone your combination medication until after you get your lab test done.

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    Are There Other Uses For The Measurement Of Total T4

    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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    Fasting And Thyroid Health: Vary The Diet

    Insulin is needed for this conversion to take place. Therefore, if insulin is low too long the lack of active T3 can become a problem. Those on a low carb diet for long periods can develop very low insulin. This impacts not only fat loss and muscle loss but can affect other hormones as well. People that already have hormone challenges are even more sensitive to this potential problem, and respond the best to the what I refer to as monthly diet variation.

    Feasting for one week a month not only helps the conversion of T4 to T3, but other hormones like estrogen and testosterone as well. The week before a womans period is what we have discovered is the best time to drive the insulin up to assist in the many hormonal needs that take place at that time.

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    What Should I Do To Prepare For A Thyroid Function Test

    How to Prevent Low Thyroid From Fasting

    Thyroid function tests usually require very little preparation.

    You dont need to fast before the blood test. And it doesnt matter if you have taken your thyroid medicine just before the blood test.

    Tell your doctor if you are taking any medication, as some medicines can alter the test results and how they are interpreted.

    It is also important to mention if you have had any X-ray tests that have used a special contrast dye, as this may contain iodine which can affect the results. Levels of thyroid chemicals also change in pregnancy, so tell your doctor if you are pregnant when the test is taken.

    Note: all newborn children have their thyroid function tested as part of the heel prick test which is offered to all babies and undertaken when they are 5 days old. See the separate leaflet called Newborn Baby Screening Tests for more information.

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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.

    T3 Resin Uptake Results

    A T3 resin uptake, also known as a T3RU, is a blood test that measures the binding capacity of a hormone called thyroxin-binding globulin . If your T3 level is elevated, your TBG binding capacity should be low.

    Abnormally low levels of TBG often indicate a problem with the kidneys or with the body not getting enough protein. Abnormally high levels of TBG suggest high levels of estrogen in the body. High estrogen levels may be caused by pregnancy, eating estrogen-rich foods, obesity, or hormone replacement therapy.

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