What are Normal Thyroid Hormone Levels?
Affiliated : TSH Test | T4 Test | T3 Test
What is thyroid hormone?
Thyroid hormone is made by the thyroid gland gland, a butterfly-shaped endocrine gland gland normally located in the lower front of the neck. Thyroid hormone is released into the blood where it is carried to all the tissues in the body. It helps the consistency use energy, stay warm and keeps the genius, kernel, muscles, and early organs working as they should. Thyroid hormone exists in two main forms : thyroxine ( T4 ) and triiodothyronine ( T3 ). T4 is the primary coil human body of thyroid hormone go around in the blood ( about 95 % ). To exert its effects, T4 is converted to T3 by the removal of an iodine atom ; this occurs chiefly in the liver and in certain tissues where T3 acts, such as in the brain. T3 normally accounts for about 5 % of thyroid gland hormone circulate in the lineage.
Most thyroid gland hormone in the blood is bound by protein, while only a minor fraction is “ free ” to enter tissues and have a biological effect. Thyroid tests may measure sum ( protein bind and rid ) or unblock hormone levels. production of thyroid hormone by the thyroid gland gland is controlled by the pituitary, another endocrine gland gland in the brain. The pituitary releases Thyroid Stimulating Hormone ( abbreviated TSH ) into the blood to stimulate the thyroid to make more thyroid hormone. The amount of TSH that the pituitary sends into the bloodstream depends on the total of thyroid hormone in the consistency. Like a thermostat, if the pituitary sense broken thyroid hormone, then it produces more TSH to tell the thyroid gland to produce more. Once the T4 in the bloodstream goes above a certain grade, the pituitary ’ mho production of TSH is shut off. In this means, the pituitary senses and controls thyroid gland production of thyroid hormone. Endocrinologists use a combination of thyroid gland hormone and TSH testing to understand thyroid hormone levels in the body.
What is a TSH test?
Blood tests to measure thyroid gland hormones are readily available and widely used. not all thyroid tests are utilitarian in all situations. TSH Test
The best room to initially test thyroid function is to measure the TSH ( Thyroid Stimulating Hormone ) horizontal surface in a blood sample distribution. Changes in TSH can serve as an “ early admonition arrangement ” – frequently occurring before the actual level of thyroid gland hormones in the soundbox becomes excessively high or excessively moo. A high TSH level indicates that the thyroid gland is not making enough thyroid hormone ( primary hypothyroidism ). On the other hand, a broken TSH horizontal surface normally indicates that the thyroid gland is producing excessively much thyroid hormone ( hyperthyroidism ). occasionally, a abject TSH may result from an abnormality in the pituitary gland, which prevents it from making enough TSH to stimulate the thyroid gland ( central hypothyroidism ). In most healthy individuals, a normal TSH value means that the thyroid is functioning by rights.
What is a T4 test?
A Total T4 trial measures the bound and unblock thyroxine ( T4 ) 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 increase thyroid gland hormone ski binding proteins and will result in a high entire T4. Testosterone or androgens and anabolic steroids are coarse causes of decreased thyroid gland hormone binding proteins and will result in a low Total T4. In some circumstances, like pregnancy, a person may have normal thyroid officiate but Total T4 levels outside of the convention citation range. Tests measuring absolve T4 – either a free T4 ( FT4 ) or free T4 index ( FTI ) – may more accurately reflect how the thyroid gland is functioning in these circumstances. An endocrinologist can determine when thyroid disease is portray in the context of abnormal thyroid binding proteins.
What is a T3 test?
T3 tests standard triiodothyronine ( T3 ) levels in the blood. A total T3 screen measures the bind and free fractions of triiodothyronine. Hyperthyroid patients typically have an elevated sum T3 level. T3 tests can be used to support a diagnosis of hyperthyroidism and can determine the asperity hyperthyroidism. In some thyroid diseases, the proportions of T3 and T4 in the blood deepen and can provide diagnostic information. A model of increased T3 volt T4 is characteristic of Graves ’ disease. On the other hand, medications like steroids and amiodarone, and severe illness can decrease the come of thyroid gland hormone the body converts from T4 to T3 ( active shape ) resulting in a lower proportion of T3. T3 levels fall late in the course of hypothyroidism and consequently are not routinely used to evaluate patients with hypoactive or surgically absent thyroid gland glands. measurement of Free T3 is possible, but is frequently not reliable and therefore may not be helpful.
What is a normal thyroid (hormone) level?
Tests often used to assess thyroid hormone status include TSH and FT4 tests. The normal value for a lab trial is determined by measuring the hormone in a big population of healthy individuals and finding the normal reference point stove. Normal ranges for thyroid tests may vary slenderly 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 convention values are 0.7 to 1.9ng/dL. Individuals taking medications that modify thyroid hormone metamorphosis and those with a history of thyroid cancer or pituitary disease may be optimally managed with a different convention FT4 range. sum T4 and Total T3 levels measure boundary and free thyroid hormone in the blood. These levels are influenced by many factors that affect protein levels in the soundbox, including medications, sex hormones, and liver-colored disease.
A normal Total T4 level in adults ranges from 5.0 to 12.0μg/dL.
A convention Total T3 tied in adults ranges from 80-220 ng/dL. rid T3 assays are frequently unreliable and not routinely used to assess thyroid routine.
What does it mean if my thyroid levels are abnormal?
Lab results Consider… High TSH, low thyroid hormone level Primary hypothyroidism High TSH, normal thyroid hormone level Subclinical hypothyroidism Low TSH, high thyroid hormone level Primary hyperthyroidism Low TSH, normal thyroid hormone level Early or mild hyperthyroidism Low TSH, high thyroid hormone level
High TSH, low thyroid hormone level Thyroiditis (Thyroid Inflammation) Low TSH, low thyroid hormone level Pituitary disease
Patterns of thyroid tests associated with thyroid disease
A high TSH and abject thyroid hormone horizontal surface ( e.g. low FT4 ) can indicate primary coil hypothyroidism. primary hypothyroidism occurs when the thyroid gland makes excessively little thyroid gland hormone. Symptoms of hypothyroidism can include feel cold, constipation, weight gain, slowed think, and decreased energy.
Causes of chief hypo thyroidism include :
- Autoimmune thyroid disease, including Hashimoto’s thyroiditis
- Thyroid gland dysfunction due to a medication (e.g. amiodarone, tyrosine kinase inhibitors, or cancer immunotherapy)
- Removal of all or part of the thyroid gland
- Radiation injury to the thyroid (e.g. external beam radiation, radioactive iodine ablation treatment)
- Excess treatment with anti-thyroid medications (e.g. methimazole, propylthiouracil)
early or mild hypothyroidism may present as a persistently elevated TSH and a normal FT4 hormone level. This blueprint is called subclinical hypothyroidism and your repair may recommend treatment. Over clock, untreated subclinical hypothyroidism can contribute to heart disease. It is important to remember that normal TSH levels in older individuals ( ages 70 and above ) are higher than the normal ranges for younger individuals. Primary Hyperthyroidism
A low TSH and a high thyroid hormone level ( e.g. high FT4 ) can indicate primary hyperthyroidism. elementary hyper thyroidism occurs when the thyroid gland makes or releases besides much thyroid hormone. Symptoms of hyperthyroidism can include tremors, palpitations, restlessness, feeling excessively ardent, frequent intestine movements, disrupted sleep, and unintentional weight unit loss.
Causes of elementary hyper thyroidism include :
- Graves’ disease
- Toxic or autonomously functioning thyroid nodule
- Multinodular goiter
- Thyroid inflammation (called thyroiditis) early in the course of disease
- Thyroid gland dysfunction due to a medication (e.g. amiodarone or cancer immunotherapy)
- Excess thyroid hormone therapy
early on or mild hyperthyroidism may present as a persistently low TSH and a normal FT4 hormone horizontal surface. This design is called subclinical hyperthyroidism and your repair may recommend treatment. Over time, untreated subclinical hyperthyroidism can worsen osteoporosis and put up to abnormal kernel rhythm.
Thyroid excitement, besides called thyroiditis, causes wound to the thyroid gland and spill of thyroid gland hormone. Individuals with thyroiditis normally have a brief time period of hyperthyroidism ( low TSH and high FT4 or Total T4 ) followed by development of hypothyroidism ( high TSH and low FT4 or Total T4 ) or resolution. Some forms of thyroiditis are transeunt, like post-partum thyroiditis or thyroiditis following an infection, and much resolve on their own without need for medicine. other forms of thyroiditis, like thyroiditis resulting from cancer immunotherapy, interferon alpha, or tyrosine kinase inhibitors, normally result in permanent hypothyroidism and require hanker term discussion with thyroid hormone substitution. Your endocrinologist will monitor your thyroid tests during thyroiditis and can help determine if you need short and hanker condition medications to balance your thyroid function and control any symptoms. Central Hypothyroidism
A depleted TSH and a abject FT4 may indicate pituitary disease. signal detection of central hypothyroidism should prompt your repair to check for problems in other pituitary hormones, an implicit in lawsuit, and you may need imaging tests to look at the pituitary gland. central hypothyroidism is treated with thyroid hormone replacement. importantly, sufficiency of thyroid substitute in central hyperthyroidism is assessed with FT4 and Total T4 tests not TSH as in primary hyperthyroidism, and insufficiency in stress hormone hydrocortisone should be assessed before starting thyroid gland discussion to prevent an adrenal gland crisis. Causes of central hypothyroidism include pituitary gland disease, such as a pituitary mass or tumor, history of pituitary operation or radiation sickness, pituitary inflammation ( called hypophysitis ) resulting from autoimmune disease or cancer immunotherapy, and infiltrative diseases. Rare causes of abnormal thyroid function
Thyroid hormone resistor
Iodine induced hyperthyroidism
TSH-secreting tumor ( TSH-oma )
Germ cellular telephone tumors
Infiltrative diseases, such as systemic scleroderma, hemochromatosis, or amyloidosis
When abnormal thyroid function tests are not due to thyroid disease
While rake tests to measure thyroid hormones and thyroid stimulating hormone ( TSH ) are wide available, it is important to remember that no all tests are utilitarian in all circumstances and many factors including medications, supplements, and non-thyroid checkup conditions can affect thyroid gland trial results. An endocrinologist can help you make common sense of thyroid gland test results when there is a discrepancy between your results and how you feel. A full first footstep is often to repeat the examination and ensure there are no medications that might interfere with the test results. Below are some coarse 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 besides cause a humble TSH. An endocrinologist can help to interpret changes in thyroid affair tests in these circumstances to distinguish non-thyroid illness from true thyroid dysfunction. Test interference
Biotin, a common accessory 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 lineage test for thyroid gland function. Individuals who have exposure to mice, like lab researchers and veterinarians, may develop antibodies against shiner proteins in their rake. These antibodies cross react with reagents in multiple thyroid serve tests and cause irregular results. A speciate try can accurately measure thyroid hormone levels and TSH in this circumstance.
I don’t feel well, but my thyroid tests are normal
Thyroid blood tests are broadly accurate and reliable. If your thyroid tests are normal, your symptoms may not be related to thyroid disease and you may want to seek extra evaluation with your primary care doctor.
How is hypothyroidism treated?
What is thyroid medication?
Thyroid Hormone Treatment
Levothyroxine is the standard of wish in thyroid hormone successor therapy and treatment of hypothyroidism. Levothyroxine ( besides called LT4 ) is equivalent to the T4 shape of naturally occurring thyroid hormone and is available in generic and brand name forms. How do I take levothyroxine?
To optimize assimilation of your thyroid medication, it should be taken with water system at a regular time each day. multiple medications and supplements decrease absorption of thyroid hormone and should be taken 3-4 hours apart, including calcium and cast-iron supplements, proton pump inhibitors, soy, and multivitamins with minerals. Because of the way levothyroxine is metabolized by the body, your doctor of the church may ask you to take an extra pill or skip a pill on some days of the workweek. This helps us to fine tune your medicine drug for your consistency and should be guided by an endocrinologist. For patients with celiac disease ( autoimmune disease against gluten ) or gluten sensitivity, a gluten release formulation of levothyroxine is available. Some individuals may have familial version that affects how the body converts T4 to T3 and these individuals may benefit from the addition of a modest drug of triiodothyronine. Liothyronine is surrogate T3 ( triiodothyronine ) thyroid hormone. This medication has a short half life and is taken doubly per day or in combination with levothyroxine. Liothyronine alone is not used for treatment of hypothyroidism long term. early formulations of thyroid gland hormone surrogate include natural or desiccated thyroid hormone extracts from animal sources. Natural or desiccated thyroid extract preparations have greater variability in the dose of thyroid hormone between batches and unbalanced ratios if T4 vs T3. Natural or animal sources of thyroid hormone typically contain 75 % T4 and 25 % T3, compared to the normal human remainder of 95 % T4 and 5 % T3. treatment with a correct balance of T4 and T3 is significant to replicate normal thyroid function and prevent adverse effects of overindulgence T3, including osteoporosis, heart problems, and mood and sleep disturbance. An endocrinologist can evaluate symptoms and thyroid tests to help balance thyroid hormone medications.
How do I know if my thyroid dose is correct?
Monitoring thyroid levels on medication
Correct dose of thyroid gland hormone is normally assessed using the lapp tests for diagnosis of thyroid disease, including TSH and FT4. thyroid tests are typically see every 4-6 weeks initially and then every 6 to 12 months once stable. In limited circumstances, such as pregnancy, a history of thyroid gland cancer, central hypothyroidism, amiodarone therapy, or use of combination T4 and T3 thyroid hormone substitute, your endocrinologist may check different thyroid tests. additionally, your endocrinologist will evaluate for symptoms of hyperthyroidism and hypothyroidism and peform a physicial examination. Women who are pregnant and women who may become pregnant should only be treated with levothyroxine ( T4 ). entirely T4 efficiently crosses the placenta to provide thyroid hormone to the developing fetus. Thyroid hormone is critical in early pregnancy for brain exploitation. normal ranges for thyroid tests in pregnancy are different and change by shipshape. Women with thyroid gland disease in pregnancy or who are considering pregnancy should be under the care of an endocrinologist to guide therapy.
Individuals with a history of thyroid cancer, even if only a parcel of the thyroid gland was removed, besides have different target ranges for TSH and FT4 tests. Thyroid hormone substitution in these individuals is closely tied to ongoing thyroid cancer surveillance, monitor of thyroid cancer tumor markers, and active assessment of recurrence gamble. These patients are optimally managed by a multidisciplinary team including an endocrinologist and endocrine surgeon. Got Questions About Normal Thyroid Hormone Levels? Please Contact Us >