Thyroid Stimulating Hormone

Is a blood test used to check for thyroid gland problems.

TSH causes the thyroid gland to make two hormones: triiodothyronine (T3) and thyroxine (T4). T3 and T4 help control your body’s metabolism.

Why It Is Done

  • To determine if the thyroid gland is working properly. An underactive thyroid gland (hypothyroidism) can cause symptoms such as weight gain, tiredness, dry skin, constipation, a feeling of being too cold, or frequent menstrual periods. An overactive thyroid (hyperthyroidism) can cause symptoms such as weight loss, rapid heart rate, nervousness, diarrhea, a feeling of being too hot, or irregular menstrual periods.
  • Find the cause of an underactive thyroid gland (hypothyroidism). TSH levels can help determine whether hypothyroidism is due to a damaged thyroid gland or some other cause (such as a problem with the pituitary gland or the hypothalamus).
  • To keep track of treatment with thyroid replacement medicine for people who have hypothyroidism.
  • To monitor the thyroid gland function in people who are being treated for hyperthyroidism. This treatment may include antithyroid medicine, surgery, or radiation therapy.
  • Double-check the diagnosis of an underactive thyroid gland in a newborn (congenital hypothyroidism).
  • Diagnose and monitor female infertility problems.

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