T3 t4 tsh normal range in pregnancy

WHAT ARE THE NORMAL CHANGES IN THYROID FUNCTION ASSOCIATED WITH PREGNANCY? HORMONE CHANGES. A normal pregnancy results in a number of important physiological and hormonal changes that alter thyroid function. These changes mean that laboratory tests of thyroid function must be interpreted with caution during pregnancy. Thyroid function tests change during pregnancy due to the influence of two main hormones: human chorionic gonadotropin (hCG), the hormone that is measured in the pregnancy test and estrogen, the main female hormone. HCG can weakly turn on the thyroid and the high circulating hCG levels in the first trimester may result in a slightly low TSH. When this occurs, the TSH will be slightly decreased in the first trimester and then return to normal throughout the duration of pregnancy. Estrogen increases the amount of thyroid hormone binding proteins in the serum which increases the total thyroid hormone levels in the blood since >99% of the thyroid hormones in the blood are bound to these proteins. However, measurements of “Free” hormone (that are not bound to protein, representing the active form of the hormone) usually remain normal. The thyroid is functioning normally if the TSH and Free T4 remain in the trimester-specific normal ranges throughout pregnancy. SIZE CHANGES. The thyroid gland can increase in size during pregnancy (enlarged thyroid = goiter). However, pregnancy-associated goiters occur much more frequently in iodine-deficient areas of the world. It ...

Hello. I'm Dr. Sandra Fryhofer. Welcome to Medicine Matters. The topic is the new guidelines on Thyroid. [ Being pregnant can be a stress test for the thyroid. The size of the gland increases by 10%. Production of thyroid hormones T3 and T4 increases by about 50%. As a result, the normal Recommendations for Testing for Thyroid Disease During Pregnancy The new recommendations for TSH levels during pregnancy are the following: • First trimester: less than 2.5 with a range of 0.1-2.5 • Second trimester: 0.2-3.0 • Third trimester: 0.3-3.0. If the TSH is greater than 2.5 at any time during pregnancy, T4 levels should be checked to determine whether the hypothyroidism is overt or subclinical. If T4 is low, the diagnosis is overt hypothyroidism, which can impair the infant's neurocognitive development. There are also increased risks for If TSH is high and the T4 is normal, the diagnosis is subclinical hypothyroidism. In this case, the next step is to check for antithyroid peroxidase antibodies. Women who are antibody positive should be treated. The effect of subclinical hypothyroidism on fetal neurocognitive development is not clear. But one large study showed lower IQ tests in the children of untreated women. Treatment is necessary when TSH is 10 or more, regardless of the T4 level. In addition, TSH should be monitored every 4 weeks during the first 20 weeks of gestation, then once again between 26 and 32 weeks. Conception in Women With Hypothyroidism What about women with hypot...

Thyroid disease is the second most common endocrine disorder affecting women of reproductive age, and when untreated during pregnancy is associated with an increased risk of miscarriage, placental abruption, hypertensive disorders, and growth restriction. Current guidelines recommend targeted screening of women at high risk, including those with a history of thyroid disease, type 1 diabetes mellitus, or other autoimmune disease; current or past use of thyroid therapy; or a family history of autoimmune thyroid disease. Appropriate management results in improved outcomes, demonstrating the importance of proper diagnosis and treatment. In women with hypothyroidism, levothyroxine is titrated to achieve a goal serum thyroid-stimulating hormone level less than 2.5 mIU per L. The preferred treatment for hyperthyroidism is antithyroid medications, with a goal of maintaining a serum free thyroxine level in the upper one-third of the normal range. Postpartum thyroiditis is the most common form of postpartum thyroid dysfunction and may present as hyper- or hypothyroidism. Symptomatic treatment is recommended for the former; levothyroxine is indicated for the latter in women who are symptomatic, breastfeeding, or who wish to become pregnant. Thyroid disease is second only to diabetes mellitus as the most common endocrinopathy that occurs in women during their reproductive years. Symptoms of thyroid disease often mimic common symptoms of pregnancy, making it challenging to identify. Po...

WHAT ARE THE NORMAL CHANGES IN THYROID FUNCTION ASSOCIATED WITH PREGNANCY? HORMONE CHANGES. Thyroid function tests change during normal pregnancy due to the influence of two main hormones: human chorionic gonadotropin (hCG) and estrogen. Because hCG can weakly stimulate the thyroid, the high circulating hCG levels in the first trimester may result in a low TSH that returns to normal throughout the duration of pregnancy. Estrogen increases the amount of thyroid hormone binding proteins, and this increases the total thyroid hormone levels but the “Free” hormone (the amount that is not bound and can be active for use) usually remains normal. The thyroid is functioning normally if the TSH and Free T4 remain in the trimester-specific normal ranges throughout pregnancy. THYROID SIZE CHANGES. The thyroid gland can increase in size during pregnancy (enlarged thyroid = goiter). However, pregnancy-associated goiters occur much more frequently in iodine-deficient areas of the world. It is relatively uncommon in the United States. If very sensitive imaging techniques (ultrasound) are used, it is possible to detect an increase in thyroid volume in some women. This is usually only a 10-15% increase in size and is not typically apparent on physical examination by the physician. However, sometimes a significant goiter may develop and prompt the doctor to measure tests of thyroid function (see The thyroid gland is a butterfly-shaped endocrine gland that is normally located in the lower fro...

Physiological changes necessitate the use of pregnancy-specific reference ranges for TSH and FT4 to diagnose thyroid dysfunction during pregnancy. Although many centers use fixed upper limits for TSH of 2.5 or 3.0 mU/L, this comment describeds new data which indicate that such cut-offs are too low and may lead to overdiagnosis or even overtreatment. The new guidelines of the American Thyroid Association have considerably changed recommendations regarding thyroid function reference ranges in pregnancy accordingly. Also a stepwise approach to interpreting these guidelines is discussed as well as the relevant role of FT4 in diagnosis. Various studies have demonstrated that with the use of fixed TSH upper limits, 8–28% of pregnant women have a TSH concentration that is considered too high [ The 2017 ATA guidelines [ • 1) Calculate pregnancy-specific and lab-specific references ranges for TSH and FT4 • 2) If 1 is not possible, adopt a reference range from the literature that is derived using a similar assay and preferably also in a population with similar characteristics (i.e. ethnicity, BMI, iodine status) • 3) If 1 and 2 are not possible, deduct 0.5 mU/l from the non-pregnancy reference range (which in most centers would results in a cut-off of roughly 4.0 mU/l) My interpretation of these recommendations is probably more strict than that of most endocrinologists or gynecologists. Lab-specific reference ranges better identify women with gestational thyroid dysfunction tha...