I dont see my dr again for a while and want to have an idea what i am dealing with. Free t4 health encyclopedia university of rochester. Slightly low free t4 thyroid disorders discussions. A total t4 measures the bound and free hormone and can change when binding proteins differ see above. In the presence of a normal thyroid stimulating hormone level tsh, this does not mean necesarily that there is too much thyroxine in the body but there is a chance that hyperthyroidism overactive thyroid is present or will. Causes of normal t3,t4 levels but low tsh levels dr. So t4 is basically a stepping stone required for t3. Symptoms of hyperthyroidism, also known as overactive thyroid, include. A free t4 measures what is not bound and able to enter and affect the. High free t4 46 but normal tsh and t3 endocrineweb. Free t4 tests can be inaccurate in some people who have interfering substances present. This cycle continues to repeat, keeping thyroid hormone levels from becoming too high or too low. Thyroid function tests american thyroid association. T4 and t3 are hormones produced by the thyroid gland and are essential for life.
John is a medical writer and editor with more than 15 years experience in the field. Free t4 may more accurately measure the physiologic amount of t4. Doctors give unbiased, helpful information on indications, contraindications, benefits, and complications. Ive had a lot of unexplained weight gain since my second child and a low free t3 so my endo put me on 5 mcg of cytomel 2 years ago. Another possibility is a tumor in the pituitary secreting too much tsh resulting in thyroid overactivity. Its one of the main glands of the body that typically produces three hormones triiodothyronine t3, thyroxine t4, and calcitonin. Knowing what your free t3 is will tell you how well your body is converting t4 to t3, or whether you are just walking around with an excess of t4 greater than normal for your situation. Nonthyroidal illness rarely secondary hypothyroidism. If tsh, free t4 and free t3 are within the normal range. Abnormal tft results guidance tsh high t4 normal t3 normal. Thyroxine, also known as t4, is the primary thyroid hormone secreted by the thyroid gland. A free t4 test is considered more accurate than a total t4 test for checking thyroid function. This condition is very similar to hypothyroidism, but some patients with it may not experience symptoms, whereas all patients with hypothyroidism will experience symptoms.
There are many treatments and ways to raise your free t3 level. This hormone is low or depressed in those people with hypothyroidism, and it is usually elevated in those with hyperthyroidism. For an excessively low or high quantity of this element is known to cause the onset of a number of chronic diseases and conditions in the body. And because most t3 is produced via the conversion of t4 into t3, if someone has. Problems with the assessment of thyroid function in pituitary disease. Patients with elevated tbg will have normal tsh, normal t4, low t3, high t3 uptake, and high tbg test numbers. I would think about secondarycentral hypothyroidism. It feels like the easy answer for optimal t3 levels.
Since t3 is the most active useable form of thyroid hormone that can be used in the cells of the body, free t3 is critically important. Therefore free t4 and free t3 levels are important please note that free t3 and free t4 are different than total t3 and total t4. Unfortunately mainstream doctors often do not test free t3. If your diet is low in iodine, your child will also have low thyroid hormone. My doctor said i have hyperthyroidism but my symptoms are more like hypothyroidism. Causes of low free t3 and normal tsh posted in thyroid disease general discussion forum.
What causes a low tsh level with a normal free t4 level. Youre getting symptoms because your thyroid gland stopped working right. T3 supplementation will almost always cause a reduction in t4 low t4, an increase in free and total t3, a drop in the tsh and a drop in reverse t3. This test measures the level of free t 4, or free thyroxine, in your blood. In response to this low level of thyroid hormones, the pituitary releases tsh to try and stimulate thyroid hormone. This test measures the level of free t4, or free thyroxine, in your blood. My t3 level of thyroid hormone are high but i experience cold intolerance, fatigue, and weight gain. Learn what symptoms lead up to a t4 test and what your results mean today. It isnt making enough thyroid hormone, which helps run many of your bodys systems. Note that the normal range for these hormones may change a bit from lab to lab. Do you have thyroid symptoms with normal lab results. Thyroid hormone replacement tsh free t4 iowa head and.
Doctors give trusted answers on uses, effects, sideeffects, and cautions. For this reason, it would seem intuitive that if a low tsh is commensurate with good health, that a high free t3 and free t4 would be, as well. Can anyone tell me what a slightly low t4 with normal tsh, t3 and t4 means. If tsh and free t4 are normal or lower than the normal range, and the free t3 levels are lower than average.
I also am shaking so much, if not careful, i will spill. Hypothyroidism involves high levels of thyroid stimulating hormone tsh and low levels of the thyroid hormones t4 and t3 however, in my clinical practice i frequently see people with low levels of t3 with normal t4 and either low or normal tsh. Its the glands further up the chain having issues hypothalamus or pituitary g. Especially t3, because of the direct effect it has on thyroid hormone as opposed to t4, which is more of a.
These labs seem at odds, with tsh suggesting overactive thyroid and ft4 underactive thyroid. Tsh is stimulated by a feedback mechanism, hence if the thyroid values are intrinsically low, then tsh will shoot up leading to stimulating the thyroid hormone further increasing the output. Congenital hypothyroidism in children stanford childrens health. This article is part of a special report on thyroid disorders.
Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms. I am a 36 year old female who has been hypothyroid for 10 years. Thyroid is a small butterfly shaped gland that sits atop the neck. Most patients who have a mildly elevated tsh have a normal free thyroxine t4 level. High freet4 comes with fatigue, rather than highenergy. It is important to first make sure that it is low t3 that is the culprit of your symptoms. Typical results in adults for the free t4 test generally range from 0. My t3 level of thyroid hormone are high but i experience. Introduction screening and treatment of subclinical. Low tsh, very high free t3, low free t4 this pattern is seen in cases of endogenous hyperthyroidism such as graves disease.
Elevated thyroidbinding globulin can be caused by sex hormone imbalances, like excessive estrogen levels, or by use of oral contraceptives in women. She is a former medical officer for the centers for disease control and prevention. With this version of hypo, the symptoms are the same as all forms, but the cause is not the thyroid conking out. Hypothyroidism is when the thyroid gland does not make enough thyroid hormone. Currently, i have two or three clinically hypothyroid patients, who have the aforementioned paradoxical normal tsh, low t4, and comfortably normal or high free t3. Symptoms, but indicates hypothyroidis, which can cause fatigue increased sensitivity to cold constipation dry skin unexplained weight gain puffy face hoarseness muscle weakness elevated blood cholesterol level muscle aches, tenderness and stiffness pain. In order to diagnose abnormal total t4 levels, we could. A very common problem that we see in our office everyday is low t3 due to thyroid underconversion. Cytomel generally does a better job of suppressing tsh than puret4 therapy. The thyroid hormones circulate in the bloodstream and act on nearly all body. An elevated thyroid stimulating hormone or low levels of thyroid hormones, including free t4, total t3, or free t3, may also signal hypothyroidism. Free t4 also called free thyroxine a healthy thyroid produces the following hormones.
The thyroid produces mainly t4, which is then converted to t3 in tissue and organs. T4 is the main form of thyroid hormone circulating in the blood. In these cases, rt3 might provide the answer to the apparent pardox. Ive been on synthroid 50 mcg for most of that time. A mildly elevated thyroid stimulating hormone tsh also called thyrotropin concentration is the most common thyroid function test abnormality encountered in everyday practice. In the cases of free t4 ft4 and free t3 ft3, the optimal zone is roughly half way between the usual lab normal lowhigh values. Subclinical hyperthyroidism sch is defined as a low thyroidstimulating hormone tsh level with normal free t4 and free t3 levels. Thyroid hormones in the blood are thyroxine measured as free t4 on the blood sample and. High levels of any of these tests total t4, free t4, or free t4 index. A high tsh with normal t3, t4 or low t3, t4 levels indicate that the patient has hypothyroidism.
I thought exercising more would help my energy levels, but its like i dont even have the. Problems with the assessment of thyroid function in. Bone mineral density may be increased with treatment of sch sor. Although the focus of this post will be on t4, triiodothyronine t3 is another thyroid hormone. Low csfserum ratio of free t4 is associated with decreased quality. T4, also called thyroxine, is the storage hormone, or. Causes of low free t3 and normal tsh thyroid disease. Ive been told, nothing to worry about, however, i wonder about my symptoms and if it could be something. Hypothyroidism low t4, high tsh onset is usually subtle and patients may only become aware of symptoms only when normal tsh level euthyroidism is restored. Doctors circle worlds largest health platform 39,273 views 1. Different patterns of thyroid function tests and their causes. A free t 4 test is used to find out how well your thyroid gland is working t 4 is one of two hormones produced by the thyroid, a butterflyshaped gland in your neck.
This algorithm provides a strategy for differentiating analytical interference, resistance to thyroid hormone, and tshsecreting pituitary adenoma in patients with a high total or free t4 and a normal or high tsh. The treatment of such patients is controversial, particularly when they have few or no symptoms and no other clinical evidence of. Abnormally low free t4 levels may signal hypothyroidism. Low free t3 and free t4 levels may indicate low thyroid function, but they may also indicate a condition known as euthyroid sick syndrome or low t3 syndrome. This thyroid lab testing pattern is common among people who use t3 medication and it can even occur to a lesser degree in those who use medications such as armour thyroid or naturethroid.
What can cause normal tsh, low free t4, anemia, leukopenia. Anemia is normocytic and normochromic, transferrin saturation is below normal range. Low tsh, high free t4, low free t3 this pattern is usually seen with thyroid medication but doesnt necessarily mean that you are hyperthyroid. Ndt naturallydessicated thyroid hormone, contains natural t3 and t4, and this too will suppress tsh more effectively because of the t3. If the t4 levels get low, the pituitary sends out more tsh to tell the thyroid to make. It is also important to bear in mind whether total tt4, tt3 or free ft4, ft3 th are. In the case of tsh, the optimal zone is skewed far toward the.
Symptoms, causes, and consequences of an overactive. Free t4 health encyclopedia university of rochester medical. T3 is the active form of thyroid hormone in that it influences many body processes, in particular the regulation of metabolism 1, 2. A mild degree of hypothyroidism is not uncommon in patients screened with thyroid blood tests, and subclinical hypothyroidism is generally defined as the presence of a normal free t4, slightly elevated tsh, and the questionable presence or absence of symptoms that may not be related to thyroid function. To see a comprehensive ebook on thyroid health, click here. Luckily, for most people with a normal pituitary, levels of tsh in the blood allow us to sort this out because if free t4 levels are too low for an individual then their tsh production is turned on and levels rise above normal and conversely if free t4 is too high then tsh is suppressed see diagram. The t3 or t4 being low represents a thyroid gland that is not working well to make enough thyroid hormones. Typically, the lower the tsh the higher the free t4, so that part makes sense. Like total t4 in adults, free t4 also varies in children according to age. Free t4 also called free thyroxine stop the thyroid. In hyperthyroidism, tsh will be low, and t3, t4 will be high. Many patients initially believe that they are suffering from normal agerelated symptoms such as general fatigue and impaired vitality. High total or free t4 analogue method normalhigh tsh.