T3 normal range by age

This question comes up a lot online: "What are the optimal reference ranges for thyroid hormone labs in children?" I hope this post serves to help parents and physicians understand optimal reference ranges for children versus reference ranges reported on actual lab results. This is an important topic as thyroid hormone is crucial for brain and global development of infants and children. Unfortunately, there are no national or international standards for reference ranges that labs use. This has resulted in sometimes huge variations in reference ranges used by different labs. Ultimately, a well-studied physician should have their own reference ranges that they use when evaluating labs. The six most important labs to obtain when assessing thyroid function, regardless of the age of the patient, are: • TSH • free T4 • free T3 • reverse T3 • TPO • TgAb There are others but these are values that assess direct thyroid hormone status. The other labs that are pertinent to thyroid hormone function are CBC, ferritin, zinc, copper and vitamin D. I'll start by reviewing in very simple terms the thyroid hormone cascade. TSH (thyroid stimulating hormone) is secreted from the pituitary gland. It's released into the blood stream where it travels to the thyroid gland. TSH docks with receptors on the thyroid gland, triggering the gland to secrete T4 (thyroxine) hormone. It also secretes some T3 (triiodothyronine) hormone. T4 and T3 are secreted in an 11:1 ratio ( every cell of the body is dep...

Like many of the glands in your endocrine system, the Throughout the day, your body may need different levels of thyroid hormones. The thyroid gland itself cannot detect these requirements but instead relies on your Doctors can determine the health of your thyroid by performing a T3 test. If you have received an abnormal What Is T3 Exactly? T3 represents only 5% of all hormones released by the thyroid. The remaining 95% consists of T4, which is then converted to T3 in the pituitary gland and the ‌Most of the T3 in your blood is attached — or bound — to proteins, and only a small percentage of it is free. A total T3 test measures both bound and free T3, whereas a free T3 test measures just free T3. Either of these tests is usually ordered after a TSH test comes back abnormal. Preparing for the T3 Test A T3 test doesn’t usually require a lot of preparation such as overnight fasting. It’s actually recommended that you continue eating as normal in the days leading up to the test and that you avoid fasting because it can impact the results. While research hasn’t shown a link between T3 levels and fasting, it can influence thyroid-stimulating hormone (TSH) levels in your body. TSH is also a hormone often tested alongside T3 and T4. Before the test, you need to tell your doctor about any medications you’re taking, as some can impact thyroid hormone levels. Depending on how much they can affect the test results, you may be instructed to continue taking the medications or to stop a...

DEFINITION: WHAT DO THE FOLLOWING PATIENTS OVER THE AGE OF 60 YEARS HAVE IN COMMON? • A 72 year old woman with “fluttering of the heart” and vague chest discomfort on climbing stairs • An 80 year old man with severe constipation who falls asleep often • A 65 year old woman who has lost strength in her legs, causing difficulty in climbing stairs;she has recently lost 15 lbs in spite of a very good appetite • A 75 year old woman who has developed difficulty swallowing and a dry cough, accompanied by hoarseness, weight gain, and dry, itchy skin • A 78 year old man with hearing loss • An 84 year old woman in whom a hand tremor has caused her to give up favorite activities. She is so depressed that she will not eat, and she has lost 12 lbs in the last 4 months. All of these patients have abnormal function of their thyroid glands. Patients 1, 3 and 6 have hyperthyroidism, that is, excessive production of thyroid hormone by their thyroid glands. Patients 2, 4 and 5 have hypothyroidism, or reduced production of thyroid hormone. While some of the symptoms of hyperthyroidism and hypothyroidism are similar to those in younger patients, it is not uncommon for both hyperthyroidism and hypothyroidism to be manifest in subtle ways in older patients, often masquerading as diseases of the bowel or heart or a disorder of the nervous system. An important clue to the presence of thyroid disease in an elderly patient is a history of thyroid disease in another close family member such as a brot...

Background Both overt hypothyroidism as well as minor elevations of serum thyrotropin (TSH) levels associated with thyroid hormones within their respective reference ranges (termed subclinical hypothyroidism) are relatively common in older individuals. There is growing evidence that treatment of subclinical hypothyroidism may not be beneficial, particularly in an older person. These findings are relevant at a time when treatment with thyroid hormones is increasing and more than 10–15% of people aged over 80 years are prescribed levothyroxine replacement therapy. Main body The prevalence of hypothyroidism increases with age. However, the reference range for TSH also rises with age, as the population distribution of TSH concentration progressively rises with age. Furthermore, there is evidence to suggest that minor TSH elevations are not associated with important outcomes such as impaired quality of life, symptoms, cognition, cardiovascular events and mortality in older individuals. There is also evidence that treatment of mild subclinical hypothyroidism may not benefit quality of life and/or symptoms in older people. It is unknown whether treatment targets should be reset depending on the age of the patient. It is likely that some older patients with non-specific symptoms and incidental mild subclinical hypothyroidism may be treated with thyroid hormones and could potentially be harmed as a result. This article reviews the current literature pertaining to hypothyroidism wit...