Thyroid Disease Diagnosis What Is Thyroid Stimulating Hormone? A Message to Your Thyroid Gland to Step up Production By Adrienne Dellwo linkedin Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic. Learn about our editorial process Adrienne Dellwo Medically reviewed by Medically reviewed by Ana Maria Kausel, MD on September 22, 2020 facebook twitter Ana Maria Kausel, MD, is a double board-certified endocrinologist affiliated with Mount Sinai St. Luke's/Mount Sinai West in New York City. Learn about our Medical Review Board Ana Maria Kausel, MD on September 22, 2020 Print Table of Contents View All Table of Contents Functions Causes of Abnormal Levels Associated Conditions TSH Test Thyroid stimulating hormone (TSH) is a hormone that’s produced by the pituitary gland in your brain for the single purpose of sending a message to the thyroid gland. The pituitary gland constantly monitors your blood for levels of thyroid hormones, and if it detects too little, it releases TSH. That tells your thyroid gland to produce more of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). If the pituitary detects too much T3 or T4, it slows down the production of TSH, which signals to your thyroid that it should produce less T3 and T4. When both glands are functioning properly, this system of communication keeps your hormone levels within the optimal range. Lars Neumann / iStock / Getty Images Thyroid Hormone Functions The thyroid gland is front and center at the base of your neck, just below your larynx (voice box) and above your sternum. It’s shaped much like a butterfly, with two lobes that are joined in the center by a narrow strip of tissue. The thyroid gland's job is to make hormones that are essential to your metabolism, growth, and development. T3 and T4 work together to regulate an array of vital functions, including: Metabolic rateWeight loss or gainHeart rateBody temperatureDigestionMuscle controlRespiratory rateBone healthBrain developmentCellular production of energyMenstrual cycleGrowth and development in children Thyroid hormones literally have an impact on every cell in your body, so when their levels are outside of normal parameters, it can have a major impact on your health. How Your Thyroid Works Causes of Abnormal TSH Levels Several different things can cause your TSH levels to be abnormal. Often, it’s due to a medical condition that impairs the thyroid gland. Some conditions that are known to do this include: Pernicious anemiaType 1 diabetesPrimary adrenal insufficiency (Addison's disease)Turner syndromeAutoimmune disease that affects the thyroid gland (Hashimoto’s disease, Graves’ disease, and some cases of lupus, rheumatoid arthritis, and Sjogren’s syndrome) Other known causes of TSH abnormalities include: AgingRadiation treatments for cancer of or near the thyroid glandThyroidectomy (removal of all or part of the thyroid gland)Non-functioning thyroid gland at birthIodine deficiencyTaking medication that’s high in iodine Iodine is essential for the proper production and function of the thyroid hormones. Your body cannot produce iodine, though, so you have to get it through your diet or nutritional supplements. Some natural sources of iodine are:Fish and other seafoodDairy productsGrainsIodized salt Associated Conditions Because it’s produced when your body is low on T3 and/or T4, high TSH test results are associated with low levels of thyroid hormone and activity. Conversely, low TSH levels are associated with high levels of thyroid hormone and activity. When levels are abnormal but only by a small amount and no symptoms are present, it’s classified as a subclinical thyroid disorder. Some people diagnosed with a subclinical thyroid disorder eventually go on to develop full-blown thyroid disease. A condition called thyroiditis, which features inflammation of the gland that interferes with hormone production, can be associated with either high levels or low levels of TSH. Diseases associated with low levels of TSH/high thyroid function are hyperthyroidism and Graves' disease. Hyperthyroidism Also called overactive thyroid, this condition accelerates your metabolism. Symptoms include: Unintended weight lossIncreased sweatingRapid heart rateIrregular heart rhythmsHigh blood pressureShortness of breathMalabsorption of nutrientsFrequent urinationInfrequent periods or no periods at allErectile dysfunctionTremorAnxiety Treating Hyperthyroidism Graves’ Disease In this autoimmune condition, the immune system’s attack on the thyroid gland causes it to malfunction and produce excess hormones. The symptoms are generally the same as those of hyperthyroidism. In addition, Graves’ is often associated with: Goiter (enlarged thyroid gland)Graves’ ophthalmopathySkin lesions Graves’ ophthalmopathy can give your eyes a bulging appearance because it causes increased pressure around the eyes. It can also cause eye sensitivity and decreased vision. This is all due to the autoimmune process. An Overview of Graves' Disease Diseases associated with high levels of TSH/low thyroid function are hypothyroidism and Hashimoto's disease. Hypothyroidism Also called underactive thyroid, this condition slows the metabolism and can lead to: Weight gainFatigueLow energy levelsMental fogFrequently being coldHair lossIrregular menstrual cycles and fertility problemsMuscle pain and crampsSlow pulseLow blood pressure Treating Hypothyroidism Hashimoto's Disease Sometimes called Hashimoto's thyroiditis, this is an autoimmune disease in which the immune system misidentifies healthy thyroid tissues as a pathogen, such as a virus or bacteria, and tries to destroy it. Symptoms are similar to those of hypothyroidism but may be more severe. Diagnosing Hashimoto's Disease Some women experience a drop in thyroid function after giving birth, which is called postpartum thyroiditis. This is typically a temporary condition, with the function returning to normal over time. TSH Testing Interpretations TSH is an important marker for determining whether someone has thyroid disease. TSH Test Result Interpretations mU/L DIAGNOSIS 4.7-10 Subclinical hypothyroidism Over 10 Hypothyroidism 0.1-0.5 Subclinical hyperthyroidism Below 0.1 Hyperthyroidism Sometimes, a doctor will order tests for TSH, free T3, and free T4 together, possibly with other tests as well. This presents a much more complete picture of how well your thyroid is functioning than just a TSH test. Understanding Thyroid Test Results A Word From Verywell Having thyroid stimulating hormone in the proper amounts is crucial to your health. If you have symptoms that may be suggestive of a thyroid disorder, it's important for you to get an appointment with your doctor. These disorders are common and treatable, so there’s no reason for you to continue dealing with unpleasant—and potentially dangerous—symptoms. Was this page helpful? Thanks for your feedback! Losing weight with thyroid disease can be a struggle. Our thyroid-friendly meal plan can help. Sign up and get yours free! Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. University of Michigan: Michigan Medicine. Thyroid hormone production and function. Updated July 28, 2019. Cleveland Clinic. Thyroid disease. Updated April 19, 2020. National Institutes of Health, Office of Dietary Supplements. Iodine: Fact sheet for consumers. Updated May 1, 2020. Sheehan MT. Biochemical testing of the thyroid: TSH is the best and, oftentimes, only test needed - A review for primary care. Clin Med Res. 2016;14(2):83-92. doi:10.3121/cmr.2016.1309 National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Hyperthyroidism. Updated May 20, 2020. Bahn RS. Graves' ophthalmopathy. N Engl J Med. 2010;362(8):726–738. doi:10.1056/NEJMra0905750 National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Hypothyroidism. Updated September 2, 2020. Additional Reading Bahn RA, Burch HB, Cooper DS, Garber JR, Greenlee MC, et al. Hyperthyroidism management guidelines. Endocr Pract. 2011;17(No.3)457. Garber JR, Cobin RH, Gharib H, Hennessey JV, Klein I, et al. ATA/AACE guidelines for hypothyroidism in adults. Endocr Pract. 2012;18(No.6)989. National Center for Biotechnology Information, U.S. National Library of Medicine. How does the thyroid gland work? Updated April 19, 2018.