PubMed Central
pmc.ncbi.nlm.nih.gov › articles › PMC5922674
How to interpret thyroid function tests - PMC
However, the population reference ranges for TH are relatively wide (especially for T4) and changes in TH levels sufficient to render a patient hypo- or hyperthyroid might not necessarily be associated with numerically abnormal T4 or T3 levels (as occurs in so-called ‘subclinical’ hypo- or hyperthyroidism). Therefore, TSH has traditionally been recommended as a frontline screening test for thyroid dysfunction, because relatively modest changes in TH levels are associated with marked excursions in TSH.
Cleveland Clinic
my.clevelandclinic.org › health › diagnostics › 24235-thyroxine-t4-test
T4 (Thyroxine) Test: What It Is, Function, Purpose & Levels
July 21, 2025 - This is a lack of T4 production due to an issue with your thyroid that’s causing your pituitary gland to release excess TSH to try to stimulate your thyroid into making more T4. Having high TSH and high T4 levels may indicate that you have an issue with your pituitary gland that’s causing it to release too much TSH, and thus triggering your thyroid to make excess T4.
High TSH and high T4
For almost one year I’m having results come back at varying times with both high TSH and T4 which contradict one another. High TSH Hypothyroidism (which I’ve been for 26 years) and high T4 indicates hyperthyroidism. My endocrinologist and her team act like they’ve never seen this. More on connect.mayoclinic.org
What causes high TSH but normal T4?
The day before my blood test I didn't eat breakfast until 530 am More on reddit.com
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August 26, 2022What does this mean? Slightly high T4 and high TSH.
You had over range or near TSH all of last year. High TSH indicates some type of thyroid disease. What time of day were all of these blood draws? High TSH with high in range FT4 could be due to Hashimoto's and/or, possibly low FT3. T4 is converted into T3. Hashimoto's can cause problems with this conversion. You'll have to retest, since TSH, FT4, and FT3 all need to be tested as a group. Blood draw needs to be first thing in the morning. Both thyroid antibodies (TPO/ab and TG/ab) need to be tested to rule out Hashimoto's. It's very important to know if you have an autoimmune disease and if your hypothyroidism is caused by autoimmune Hashimoto's. Which type of thyroid replacement hormones and doses did you try when you experienced intolerance? What sort of symptoms did you experience, and what were your TSH and FT4 when you tried thyroid replacement hormone? More on reddit.com
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October 8, 2021High TSH, but normal T3 and T4
Absolutely we can have hypo symptoms when TSH is High, but T4 and T3 are normal! The time to begin treating hypo is when TSH is High. If we wait until T4 and T3 are Low, then we may develop very unpleasant symptoms and possibly even other health conditions. I briefly went clinically hypo (Low T4 and Low T3) and had awful digestive symptoms and heart burn. I had never had heart burn before! I also felt depressed and unmotivated. I was surprised by how long it took my mental health to get back to normal. When you are being diagnosed with hypo, they often want to re-check your thyroid hormone levels to confirm that TSH is staying Abnormally High. Once they confirm this, then they are likely to prescribe thyroid medication. They know that the High TSH wasn’t just a fluke, that it’s here to stay, and that you can benefit from medication. If you are pregnant or trying to conceive, TSH needs to be below 2.5. If you are pregnant then Dr should likely prescribe thyroid medication immediately instead of waiting to re-test. The fetus uses our thyroid hormone to grow and develop normally during 1st trimester. Sometime after first trimester you still need normal range TSH to be as healthy as you can be, but baby’s thyroid gland will likely be producing thyroid hormone for baby. More on reddit.com
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February 28, 2023Videos
01:43
TSH and T3/T4 - Whats the difference? Lab Values/ABG - Shorts | ...
04:48
Hyperthyroidism (Overactive Thyroid): Symptoms, Causes & Diagnosis ...
16:10
19 Signs of HYPERTHYROIDISM (Graves Disease) You Can See: Doctor ...
02:11
TSH and Thyroid Function Tests | UCLA Endocrine Center - YouTube
02:36
Thyroid Stimulating Hormone | UCLA Endocrine Center - YouTube
03:27
I Have Symptoms of Hypothyroidism but My TSH Is Normal | UCLA ...
American Thyroid Association
thyroid.org › home › thyroid function tests
Thyroid Function Tests | American Thyroid Association
June 8, 2020 - The amount of TSH that the pituitary sends into the bloodstream depends on the amount of T4 that the pituitary sees. If the pituitary sees very little T4, then it produces more TSH to tell the thyroid gland to produce more T4. Once the T4 in the bloodstream goes above a certain level, the pituitary’s production of TSH is shut off.
Mayo Clinic
mayoclinic.org › diseases-conditions › hypothyroidism › diagnosis-treatment › drc-20350289
Hypothyroidism (underactive thyroid) - Diagnosis and treatment - Mayo Clinic
December 10, 2022 - Understand what happens when your thyroid is underactive and learn about treatment for this condition.
NHS
nhs.uk › conditions › overactive-thyroid-hyperthyroidism › diagnosis
Overactive thyroid (hyperthyroidism) - Diagnosis - NHS
thyroxine (T4) – another of the ... person of your age. A low level of TSH and high levels of T3 and/or T4 usually means you have an overactive thyroid....
University of Michigan Health
uofmhealth.org › home › our care › specialties & services › hyperthyroidism & graves’ disease
Hyperthyroidism & Graves’ Disease | University of Michigan Health
A high TSH level indicates that the body does not have enough thyroid hormone. A TSH level lower than normal indicates there is usually more than enough thyroid hormone in the body and may indicate hyperthyroidism.
Advocate Health
adscresources.advocatehealth.com › does-tsh-tell-the-whole-story
Does TSH tell the whole story? | Adult Down Syndrome Center
This page shares information on thyroid testing for individuals with Down syndrome.
Mayo Clinic Connect
connect.mayoclinic.org › discussion › high-tsh-and-high-t4
High TSH and high T4 | Mayo Clinic Connect
September 9, 2023 - High TSH means your thyroid is slow. That with a high T4 is odd but it’s possible you are not absorbing it or you might have an allergy to it like my sister and I. Additionally make sure you are not on Biotin when your thyroid is checked again. My sister and I just take T3 because T4 either ...
American Academy of Family Physicians
aafp.org › pubs › afp › issues › 1998 › 0215 › p776.html
Subclinical Hypothyroidism: Deciding When to Treat | AAFP
February 15, 1998 - In another study11 of 69 female patients with subclinical hypothyroidism, a clinical index based on symptoms and physical signs was shown to be more abnormal in patients with higher TSH levels, even though all patients had normal serum levels of T4 and free T4.
UCLA Health
uclahealth.org › medical-services › surgery › endocrine-surgery › conditions-treated › thyroid › normal-thyroid-hormone-levels
Normal Thyroid Hormone Levels - Endocrine Surgery | UCLA Health
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. Primary Hypothyroidism A high TSH and low thyroid hormone level (e.g.
Oxford Academic
academic.oup.com › jcem › article › 109 › 4 › 1094 › 7439666
Approach to the Patient With Raised Thyroid Hormones and Nonsuppressed TSH | The Journal of Clinical Endocrinology & Metabolism | Oxford Academic
March 15, 2024 - It is well recognized that in some thyroxine-treated patients with goitrous or dysgenetic CH, but without any additional defect in genes mediating TH action, circulating TSH remains raised despite FT4 concentrations being within the normal range, such that a higher dosage of T4 (with resultant elevated FT4 concentrations) is required to normalize TSH (67, 68).
Children's Mercy Kansas City
childrensmercy.org › health-care-providers › pediatrician-guides › endocrinology › abnormal-thyroid
Abnormal Thyroid - Children's Mercy
TSH is the single most sensitive test used to diagnose primary hypothyroidism (high TSH) or hyperthyroidism (low TSH). In these situations, free T4 (FT4) is low or high respectively; when this occurs, the diagnosis of an overt thyroid illness ...
British Thyroid Foundation
btf-thyroid.org › subclinical-thyroid-disease
Subclinical thyroid disease
Learn about subclinical (borderline) thyroid conditions
American Thyroid Association
thyroid.org › home › patients portal › clinical thyroidology for the public › january 2024 › vol 17 issue 1 p.13-14
Increased FT4 and incompletely suppressed TSH levels are mainly related to levothyroxine use
January 8, 2024 - TSH levels are opposite to FT4 levels. When the thyroid is underactive and FT4 levels are low, TSH levels go up. When the thyroid is overactive and FT4 levels are high, TSH levels go down.
University of Michigan Health
uofmhealth.org › home › our care › specialties & services › hyperthyroidism & graves’ disease
Hyperthyroidism and Graves' Disease
A high TSH level indicates that the body does not have enough thyroid hormone. A TSH level lower than normal indicates there is usually more than enough thyroid hormone in the body and may indicate hyperthyroidism.
British Thyroid Foundation
btf-thyroid.org › thyroid-function-tests
Thyroid function tests
BTF patient leaflet on thyroid function tests
NHS
nhs.uk › conditions › underactive-thyroid-hypothyroidism
Underactive thyroid (hypothyroidism) - NHS
You may have blood tests to check how much thyroid-stimulating hormone (TSH) and thyroxine (T4) is in your blood.
MedlinePlus
medlineplus.gov › home › medical tests
Thyroxine (T4) Test: MedlinePlus Medical Test
TSH tells your thyroid how much hormone to make. Normally, if your T4 levels are too low, your pituitary makes more TSH to make your thyroid work harder. If your T4 levels are too high, your pituitary stops making TSH.
Mayo Clinic
mayoclinic.org › diseases-conditions › hyperthyroidism › diagnosis-treatment › drc-20373665
Hyperthyroidism - Diagnosis and treatment - Mayo Clinic
November 30, 2022 - Understand what happens when your thyroid is overactive and learn about treatment for this condition.
Mount Sinai
mountsinai.org › health-library › report › hypothyroidism
Hypothyroidism Information | Mount Sinai - New York
When thyroxine (T4) levels drop ... T4 is the key hormone produced in the thyroid gland. Low levels of T4 produce hypothyroidism, and high levels produce hyperthyroidism....