Several factors can affect the results of thyroid tests, blood tests used to measure thyroid stimulating hormone (TSH),Trijoodthyronine (T3)AndThyroxine (T4)and levels critical to thyroid health.
some may be short-livedFluctuations in thyroid hormone levelsThis disappears when you change the dose of the drug, or there is a slight difference in the results when you change the time of the test. other influencing factorsThyroid test resultsIt could be long term (like pregnancy) or lifestyle factors (like smoking) could change the levels recorded on your test.
This article discusses 10 factors that can affect thyroid blood test results. It explains why they can change your results and, in some cases, how to limit the effects of thyroid tests.
Results of fasting and thyroid tests
Research shows that time of day and fasting can affect your results. Your results may be higher if you take the test early in the morning after an overnight fast.(thyroid stimulating hormone) levelsIf you take your blood test at night when you are not fasting, your TSH level will be low.
If you have that could be a problemsubclinical hypothyroidismThis happens when your TSH is slightly elevated but normalFree T4, but no symptoms. Free T4 is the active form of T4.
Subclinical hypothyroidism can be missed if you check at night and are not fasting. Ask your healthcare provider if you should fast for TSH and related thyroid tests.
Stress and thyroid test results
Factors that can affect thyroid test results include mental stress and general stress on the body, such as not getting enough sleep or eating enough.
The evidence for the effects of these things is unclear. Still, it's a good idea to check your thyroid levels under the same conditions every time. This helps prevent false fluctuations in test results.
If you are on thyroid hormone replacement, it is best to test under the same conditions each time. Schedule your TSH test at the same time of day. If you fast for one test, fast for all tests.
Your weight and weight can affect thyroid function and affect thyroid tests. For example, TSH and thyroid hormone levels increase as the hormones are released.Leptin, which also increases with obesity.
However, many factors can affect how your thyroid function interacts with your weight and weight. In general, there arehyperthyroidismtend to be lighter in weight, and those with lower functioning tend to beThyroid-related weight gain.
Body Mass Index and Thyroid Function
Recognizing the limitations of body mass index (BMI) in assessing thyroid health, researchers are exploring new tests such as waist-to-hip ratio (WHR) and body shape index (ABSI). They found more nuance in how weight and weight affect thyroid function.
The relationship between thyroid hormones, metabolism and body weight
The effects of smoking on thyroid function have been known for decades, and most of themtriiodothyronine(free T3) and lowers TSH levels in smokers. A recent study of more than 5,700 people in the Netherlands also found slightly higher free T4 levels when comparing smokers, former smokers, and never smokers.
Thyroid tests in former smokers show elevated TSH and low T4. The reason why smoking affects thyroid function is still under investigation.
Smoking and thyroid disease
Some studies show lower free T4 levels than alcohol drinkers. Free T3 and Free T4 levels are also lowstop drinking.
The reasons for changes in thyroid levels in alcohol drinkers are unknown, but there is some evidence that alcohol affects other hormone-producing structures that affect thyroid function, includinghypothalamus(MARKET) jpituitaryGland (thyroid stimulating hormone).
It can also be part of the drink itself, such asResveratrolThe polyphenols in red wine act on the thyroid gland and thus influence the results of the thyroid test.
What are Polyphenols?
Diet and thyroid test results
Iodine deficiency has long been known to cause hypothyroidism, but many other foods also affect TSH and thyroid hormone levels. Those being studied include:
- soy products
- olive oil
- Broccoli and other Brassicas
- tea and coffee
Several studies have shown that a diet high in processed foods can affect TSH and thyroid hormone levels. A 2021 study of 4,585 people found thyroid-related changes in people whose diets included protein and fats (such as bacon and sausage), sources of sugar (such as juice), and grains (such as white bread).
Iodine and thyroid tests
About a week before the thyroid scan test, you may be asked to avoid iodine in foods such as seaweed or in medications. Iodine is one of the factors that can affect the results of thyroid tests because a small amount of radioactive iodine is used during the scan.
Nutrition tips for thyroid patients
Drug use and thyroid test results
Certain medications can cause thyroid dysfunction. These medications can interfere with your thyroid hormone levels or how it works. This causes your TSH to go off as your body tries to compensate for high or low thyroid hormones.
Thyroid hormone function
Some medicines can change how thyroid hormones work and test results.These include:
- Petrochemie (lithium)
- Paxilon (amiodarone)
- iodineKelp supplements
- Immunomodulatory drugs such asalfa interferonin interleukin-2
- Tyrosinekinaseremmers, zoals Nexavar (sorafenib) of Sutent (sunitinib)
Thyroid tests and birth control
Estrogen, like the estrogen in birth control pills, can lead to high levels of T3 and T4. If you are on estrogen, make sure you get TSH and free T4 testing as part of your thyroid evaluation, as they are usually unaffected.
Thyroid hormone absorption
Certain supplements and medications can interfere with your body's ability to absorb thyroid medication. These include:
- calcium carbonate
- Iron sulfate
- Proton pump inhibitors, such as Prilosec (omeprazole) and Prevacid (lansoprazole)
These can prevent you from getting enough of the drug in your system. Therefore, it is generally recommended not to take any supplements or medications within three to four hours of taking your thyroid medication.
How to take thyroid medication
Thyroid hormone measurements
Other drugs can interfere with laboratory measurements of the thyroid gland. These drugs do not affect the actual function of the thyroid gland.
Some examples are:
- Certain non-steroidal anti-inflammatory drugs (NSAIDs)
- certain anticonvulsants
- heparin(an anticoagulant)
- Lasix (furosemide)
- Glucocorticoïden(steroids such as cortisone)
Studies have shown that supplementsBiotinIt may interfere with the results of thyroid blood tests.If you are taking biotin, stop taking it two days before your thyroid blood test.
Certain medications and supplements can interfere with your test results. Some change the way your thyroid works or interfere with your body's ability to absorb thyroid medications. Others may interfere with the test itself.
Thyroid levels during pregnancy
Changes in thyroid hormone levels during pregnancyIn fact, the range that is considered normal also changes during pregnancy. What is considered normal may vary slightly depending on the lab that performed the blood test.
Thyroid values are measured in milliunits per liter (mIU/L) and picomoles per liter (pmol/L). A mole is a measure of a large number of very small things such as atoms and molecules. A picomole is one billionth of a mole.
Normal ranges for non-pregnant people are as follows:
- TSH: 0,5-4,7 mUI/L
- T4 Free (FT4): 8.0-18 pmol/L
- T3 Vrij (FT3): 2.30-4.2 pmol/L
Pregnant women have different normal ranges. The American Thyroid Association (ATA) recommends that health care providers use these trimester ranges when evaluating thyroid tests in pregnant women.
|the first season||second season||third semester|
|TSH||0.1 - 2.5mIU/L||0.2 - 3.0mIU/L||0.3 - 3.0mIU/L|
|FT4||10,30-18,11 pmol/l||10,30-18,15 pmol/l||10,30-17,89 pmol/l|
|FT3||3,80-5,81 pmol/l||3,69-5,90 pmol/L||3,67-5,81 picomol/liter|
Disease and thyroid test results
Certain medical conditions can temporarily affect thyroid hormone results. Diarrhea can interfere with the absorption of medications and may affect your test results. episodes of infection or inflammation, such aslupusIt can also affect.
a syndrome called nonthyroid disease ornormal thyroid functionThe syndrome can also affect thyroid function and test results. This is a serious illness requiring hospitalization.
People with this condition have normal TSH levels and low T4 and T3 levels.These changes in thyroid levels are thought to be protective. Therefore, people with this condition will not receive treatment to correct thyroid levels.
exposure to toxic substances
Some heavy metals and other toxins can interfere with thyroid function, which can affect thyroid hormone levels and test results. These environmental exposures include:
- nitrate fertilizer
- Perfluoroalkyl Substances (PFAS) "Forever" chemicals
These toxins can change the way thyroid hormones are produced and metabolized (used in the body). However, studies of these compounds have had mixed results, and scientists continue to work to understand how these toxins affect short- and long-term thyroid function.
Different labs and test types
Keep in mind that different types of tests, or even the same test performed in different laboratories, may produce inconsistent results or use different ranges.Talk to your healthcare provider about the types of blood tests or imaging tests you will have and howpathologyA (laboratory) or radiological examination is performed.
External factors can affect the results of your thyroid test. This may include whether you ate before the test, what time of day you took the test, and factors such as stress, diet, and sleep.
Some medications and supplements can also affect your results. This may be because they alter thyroid function. It may also be because they decrease the body's ability to absorb thyroid hormones. Other medications and supplements can interfere with the test itself.
Normal thyroid levels are different in pregnant women than in non-pregnant people. Certain medical conditions can also interfere with your results.
Verywell Health uses only high-quality sources, including peer-reviewed research, to back up the facts in our articles. read ourpublishing processLearn more about how we fact-check and ensure our content is accurate, trustworthy and reliable.
Nair R、Mahadevan S、Muralidharan RS、Madhavan S.Do fasting or fed states affect thyroid function tests? Indian Journal of Endocrinology and Metabolism2014;18(5):705-7. Department of the Interior: 10.4103/2230-8210.139237
Mahadevan S、Sadacharan D、Kannan S、Suryanarayanan A.Does timing of sample collection or food intake change thyroid function tests? Indian Journal of Endocrinology and Metabolism. 2017；21(3):369-372。 doi:10.4103/ijem.IJEM_15_17
Demir S, Kara Y, Melikoğlu M, Aydın K, Özderya A, Subaşı HE,and others.New anthropometric measurements: relationship with euthyroid obese subjects.Curious15 dec 2021;13(12):e20435. doi: 10.7759/cureus.20435.
Gruppen EG、Kootstra-Ros J、Kobold AM、Connelly MA、Rope D、Bos JHJ、and others.Smoking Linked to Higher Thyroid Hormone Levels and Lower TSH Levels: PREVEND Study.endocrienMarch 2020;67(3):613-622. doi: 10.1007/s12020-019-02125-2.
Babić Leko M、Gunjača I、Pleić N、Zemunik T.Environmental factors that affect TSH and thyroid hormone levels.International journal of molecular sciences2021. 17;22(12):6521.doi:10.3390/ijms22126521.
Oliveira KJ、Chiamolera MI、Giannocco G、Pazos-Moura CC、Ortiga-Carvalho TM。Thyroid dysfunction: from nature to chemistry.J Mol Endocrinology13 July 2018: JME-18-0081. doi: 10.1530/JME-18-0081.
Sathyapalan T、Rigby AS、Bhasin S、Thatcher NJ、Kilpatrick ES、Atkin SL。Effects of soy on men with type 2 diabetes and subclinical hypogonadism: a randomized controlled trial.Journal of Clinical Endocrinology and Metabolism... 1 February 2017: 102(2): 425–4 doi:10.1210/jc.2016-2875.
Brdar D, Gunjača I, Pleić N, Torlak V, Knežević P, Punda A,and others.Effects of food and nutrition groups on thyroid hormone levels in healthy individuals.Power supply2021 nov-dec;91-92:111394. doi: 10.1016/j.nut.2021.111394.
National Institute of Diabetes and Digestive and Kidney Diseases.Thyroid control.
Koulouri O, Moran C, Halsall D, Chatterjee K, Gurnell M.Difficulty measuring and interpreting thyroid function tests.Best Practice Res Clin endocrien metabolisme. 2013;27(6):745-62. doi:10.1016/j.beem.2013.10.003
Ahmadieh H, Salti I.Thyroid dysfunction caused by tyrosine kinase inhibitors: a review of the incidence, pathophysiology, clinical relevance and treatment..Biomedical Research Center. 2013；2013：725410。 doi:10.1155/2013/725410
American Thyroid Association.Testing thyroid function.
Guzman-Prado Y, Vita R, Samson O.Concomitant use of levothyroxine and proton pump inhibitors in patients with primary hypothyroidism: a systematic review.J Gen Intern Med2021；36：1726–1733。 doi:10.1007/s11606-020-06403-y
This article adds S, Ruggieri RM, Trimarchi F.30 Thyroid and medicines.exist:Thyroid diseaseBoca Raton, Florida: CRC Press.
Barbecino G.Misdiagnosis of Graves' disease with apparently severe hyperthyroidism in a patient taking a high dose of biotin. thyroid2016;26(6):860-3. doi:10.1089/thy.2015.0664
Lewandowski K.Reference ranges for TSH and thyroid hormones.Not related to thyroid2015;8(supplement 1):A17. doi: 10.1186/1756-6614-8-S1-A17
Alexander EK, Pearce EN, Brent GA etc.American Thyroid Association 2017 Guidelines for the Diagnosis and Treatment of Thyroid Disorders in Pregnancy and Postpartum.thyroid. 2017；27(3):315-389。 doi:10.1089/thy.2016.0457
Vandenberg G.Non-thyroid disease in the ICU: a syndrome with different faces.thyroid. 2014;24(10):1456-65。 doi:10.1089/thy.2014.0201
Razvi S, Bhana S, Mrabeti S.Interpretation of thyroid stimulating hormone causes challenges in diagnosing thyroid dysfunction.Journal of thyroid researchSeptember 22, 2019; 2019:4106816. two: 10.1155/2019/4106816.
Akarsu S、Akbiyik F、Karaismailoglu E、Dikmen ZG。Pregnancy-specific reference intervals for thyroid function tests during pregnancy.clinical chemistry laboratory genetics.2016;54(8):1377-83。 DOS:10.1515/cclm-2015-0569
Yildirim N, Dogan S, Atakan N.Evaluation of thyroid function in patients with acne vulgaris treated with systemic isotretinoin.Dermatological treatment J.2017;28(2):141-144. Home Office: 10.1080/09546634.2016.1214232.
run throughMaria Chaumont
Mary Shomon is a writer and advocate for thyroid health and hormones. She is the author of The Thyroid Diet Revolution.
View our editorial process
Meet our Board of Medical Experts
Was this page helpful
Thank you for your opinion!
Do you have an opinion?
The thyroid gland needs the mineral iodine to make thyroid hormones. Iodine is found mainly in seafood, seaweed, plants grown in iodine-rich soil and iodized salt. Too little iodine can lead to hypothyroidism. Too much iodine can make hypothyroidism worse in people who already have the condition.What can throw off thyroid test results? ›
- Certain medications and supplements.
- The time between the last time you took your thyroid medication and when a provider draws your blood. ...
- Whether you ate before your test (only a factor with thyroid scans).
- Stress, including the effects on a non-thyroidal illness.
The thyroid gland needs the mineral iodine to make thyroid hormones. Iodine is found mainly in seafood, seaweed, plants grown in iodine-rich soil and iodized salt. Too little iodine can lead to hypothyroidism. Too much iodine can make hypothyroidism worse in people who already have the condition.What is the most sensitive marker of thyroid status? ›
This supports the role of TSH, in the absence of hypothalamic/pituitary disease, as the most sensitive marker of thyroid function.What should you not do before thyroid test? ›
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.Does caffeine affect thyroid blood test? ›
Scientific studies that assessed the effects of caffeine consumption on TSH (a hormone that affects thyroid function) concentrations, observed reduced TSH concentrations as a result of consuming an amount of caffeine equivalent to three cups of coffee.What messes with TSH levels? ›
Smoking mainly led to a decrease in TSH levels and an increase in triiodothyronine (T3) and thyroxine (T4) levels, while BMI levels were positively correlated with TSH and free T3 levels. Excess iodine led to an increase in TSH levels and a decrease in thyroid hormone levels.What can falsely elevate TSH? ›
Medication Use and Thyroid Test Results. Certain medications can cause thyroid dysfunction. These drugs can interfere with your thyroid hormone levels or with their action. This may alter TSH because your body may try to compensate for the high or low thyroid hormones.Can dehydration cause high TSH? ›
Dehydration can cause an increase in cortisol production stressing the adrenals and further initiate production of TSH, which again has a negative impact on thyroid.What are inflammatory markers for thyroid? ›
Available studies confirmed a link between thyroid function and inflammatory markers, such as ferritin, fibrinogen, erythrocyte sedimentation rate, interleukin-8, interleukin-15, or LYMPH (14, 20, 24).
- Feeling tired or lacking energy even after getting enough sleep.
- Sudden weight loss or weight gain that cannot be explained by changes in diet or exercise.
- Mood swings, irritability, anxiety, or depression.
- Sleep disturbances, insomnia, or excessive sleepiness.
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 a different range as guided by an endocrinologist.What vitamins should I avoid before thyroid test? ›
The ATA has recommended that patients stop taking biotin for at least 2 days before thyroid testing to avoid the risk of having a misleading test.What time of day is best for thyroid test? ›
It is best to have the test early in the morning. Experts do not fully agree on what the upper number should be when diagnosing thyroid disorders. Some labs will use a higher normal range limit for older people (even as high as 7 µU/mL). Normal value ranges may vary slightly among different laboratories.
So again, with this medication type, I recommend getting your thyroid function tests done first thing in the morning before taking your medications, bringing your medications with you, and taking them right after you complete your thyroid tests, to ensure that you get the most accurate lab results.Does sleep affect thyroid test? ›
Sleep deviation can alter the function of the human hypothalamic-pituitary-thyroid axis; and is associated with altered levels of TSH, T4, and T315. There is also a correlation between poor sleep quality and subclinical hypothyroidism16.What medications affect thyroid blood test? ›
- Amiodarone. Amiodarone can cause transient alterations of thyroid function tests, as well as overt hypothyroidism or hyperthyroidism. ...
- Lithium. ...
- Interferons (IFN) ...
- Tyrosine Kinase Inhibitors (TKIs) ...
- Alemtuzumab. ...
- Iodine-containing medications and agents.
Sleep loss can also affect the function of the human hypothalamo-pituitary-thyroid axis. In contrast to the effects of sleep deprivation in rodents, acute sleep loss in humans is associated with increased TSH, T4, and T3,6,7 and human sleep is believed to have an acute inhibitory effect on overnight TSH secretion.How quickly can thyroid levels change? ›
Daily circadian rhythms cause TSH to fluctuate by as much as 0.95 mIU/mL to 2.0 mIU/mL throughout the day. TSH levels are highest in the early morning and decrease late afternoon to mid-evening. TSH levels even fluctuate on average 0.75 mIU/mL on a monthly basis in healthy adults.What organ does TSH affect? ›
TSH tells your thyroid how much thyroid hormone it needs to make. If the thyroid hormone levels in your blood are too low, your pituitary gland makes larger amounts of TSH to tell your thyroid to work harder. If your thyroid hormone levels are too high, the pituitary gland makes little or no TSH.
Experts have suggested that the standard TSH range could be missing as many as 75% of people with low thyroid. So if your TSH is 2.5 or higher, and you have symptoms of low thyroid, ask your doctor for some additional thyroid tests, like Free T3 and Free T4.Can vitamins cause thyroid problems? ›
For example, many thyroid supplements contain high amounts of iodine and may contain thyroid hormones. Taking these supplements can lead to dangerous side effects and create thyroid issues in people with healthy thyroid function ( 11 ).Can TSH be high temporarily? ›
Slightly elevated TSH levels are usually detected by accident during a routine examination. But taken on their own they don't pose any health risk. It's also possible that TSH levels are high only temporarily, for example after intense physical activity.What are the 4 common household substances attacking your thyroid? ›
While heavy metals are abundant in the environment, four specific heavy metals damage the thyroid the most. Those heavy metals are aluminum, cadmium, lead, and mercury.Can stress cause TSH to rise? ›
Therefore, even under the same stress conditions, TSH levels may vary from person to person. In addition, stress exacerbates autoimmune thyroid diseases, such as Graves' disease and Hashimoto's thyroiditis, leading to elevated thyroid hormone and decreased TSH levels .What is the most common inflammatory disease of the thyroid? ›
Thyroiditis represents a group of conditions that cause inflammation of your thyroid gland. Hashimoto's thyroiditis is the most common type.What triggers thyroid inflammation? ›
An inflamed thyroid may occur in response to a viral infection (viral thyroiditis) or a bacterial infection (bacterial thyroiditis), after radiation, or in response to certain medications. Your doctor will determine the cause of your thyroiditis and will then treat the condition as needed.Where do you feel thyroid inflammation? ›
The most obvious symptom of subacute thyroiditis is pain in the neck caused by a swollen and inflamed thyroid gland. Sometimes, the pain can spread (radiate) to the jaw or ears. The thyroid gland may be painful and swollen for weeks or, in rare cases, months.What are the red flags for thyroid problems? ›
The lack of thyroid hormones can cause disturbances in your metabolism, including your heart rate and body temperature. Fatigue, sensitivity to the cold, constipation, dry skin, and unexpected weight gain are among the main symptoms.What food should be avoided in thyroid? ›
Cruciferous vegetables – Vegetables such as broccoli, cabbage, kale and Brussels sprouts can inhibit the production of thyroid hormone. This is especially common in those who have an iodine deficiency. Digesting these vegetables can block the ability to absorb iodine, which is needed for normal thyroid function.
A swollen fingertip, curved nail, and thickening skin above a nail are often signs of thyroid disease.What is an alarming TSH level? ›
If your TSH level is higher than 10 mIU/L, you should start treatment, because you will very likely develop symptoms of an underactive thyroid, even if you don't have them now.What should my TSH be for my age? ›
|18–30 years||0.5–4.1 mU/L||> 4.1 mU/L|
|31–50 years||0.5–4.1 mU/L||> 4.1 mU/L|
|51–70 years||0.5–4.5 mU/L||> 4.5 mU/L|
|71–90 years||0.4–5.2 mU/L||> 5.2 mU/L|
The best way to control your thyroid is to incorporate Vitamin A in your daily life routine. All you need to do is to consume food products that are high in Vitamin A. The most common Vitamin A rich foods are; yellow and green veggies, carrots, eggs, apricots, spinach, carrots, etc.Can thyroid levels change suddenly? ›
If you do not take your thyroid medications consistently or correctly, the therapeutic drug level—meaning the concentration of medication in your body needed for the drug to work—can quickly drop. Without a consistent therapeutic drug level, your thyroid hormone levels can fluctuate, sometimes precipitously.What can cause falsely low TSH? ›
The presence of human anti-animal antibodies in patient serum may interfere with TSH measurement . If the antibodies block TSH binding to capture or detection antibodies in the assays, negative interference will occur, leading to falsely low TSH levels.Can stress affect TSH levels? ›
In addition, stress exacerbates autoimmune thyroid diseases, such as Graves' disease and Hashimoto's thyroiditis, leading to elevated thyroid hormone and decreased TSH levels .What causes fluctuation in TSH levels? ›
TSH levels fluctuate over time within a person, in euthyroid individuals as well as in most (un)treated patients with thyroid disorders, ranging from minutes, hours, months, to years. These within-person variations in TSH levels are mainly caused by pulsatile secretion, circadian rhythm, seasons, and ageing.What is the best time of day to have a thyroid test? ›
TSH levels measured in blood samples drawn in the afternoon should be viewed with caution, as they may be falsely low and appear normal. Samples for all thyroid tests should be collected first thing in the morning.Which vitamin is not good for thyroid? ›
According to the Mayo Clinic, supplements such as calcium, iron, multivitamins containing iron, and antacids containing magnesium or aluminum can potentially have interactions with thyroid medications.
Circulating TSH shows a normal circadian rhythm with a peak between 11 pm and 5 am and a nadir between 5 pm and 8 pm.Can thyroid tests be wrong? ›
Well I'm going to tell you why, in too many cases, the TSH test is unreliable — in which case you could indeed be hypothyroid, but it's going undetected. As a brief reminder, your pituitary pumps out TSH when your thyroid hormones are too low.Can lack of sleep affect TSH levels? ›
Jauch-Chara et al. indicated that an up-regulation of pituitary-thyroid activity, after short-term total sleep deprivation, led to an increase in TSH levels. Kuetting et al. found that sleep deprivation significantly increases cardiac contractility, blood pressure, and stress hormone secretion.What does thyroid anxiety feel like? ›
Anxiety Symptoms to Watch For
If you've been diagnosed with hypothyroidism, anxiety symptoms to monitor yourself for include: Insomnia. Feeling “on edge” a lot. Muscle tension.
They also measured their levels of T4 and T3. The researchers found that the thyroids of people with anxiety disorders exhibited signs of inflammation. They also detected thyroid antibodies in these individuals. Even though the participants' thyroid glands were inflamed, they were not significantly malfunctioning.What medications can affect TSH levels? ›
- Glucocorticoids. Glucocorticoids have long been known to affect serum TSH levels in humans (3;4). ...
- Dopamine/bromocryptine. ...
- Somatostatin analogs. ...
- Rexinoids. ...
- Other medications that may affect TSH levels.
Daily circadian rhythms cause TSH to fluctuate by as much as 0.95 mIU/mL to 2.0 mIU/mL throughout the day. TSH levels are highest in the early morning and decrease late afternoon to mid-evening. TSH levels even fluctuate on average 0.75 mIU/mL on a monthly basis in healthy adults.Can diet affect TSH levels? ›
Generally, there's no hypothyroidism diet. Although claims about hypothyroidism diets abound, there's no evidence that eating or avoiding certain foods will improve thyroid function in people with hypothyroidism. However, adequate dietary iodine is essential for normal thyroid function.