Meaning of Thyroid Hormone

What are thyroid hormones?

The thyroid is an endocrine gland located in the front of the neck that produces thyroxine (T4) and triiodothyronine (T3). These hormones influence gene expression, energy use, growth, and development in almost all tissues.

The description 'metabolic hormone' summarizes its key functions, but it does not mean it is a hormone solely for weight.

How are T3 and T4 different?

The thyroid primarily secretes T4 and secretes a small amount of T3 directly. Deiodinase enzymes in the blood and various tissues, such as the liver and kidneys, convert T4 into the more active T3.

T4 serves largely as a precursor and storage form, while T3 binds to nuclear receptors to act strongly. Total concentration and free hormone concentration are also interpreted separately.

Is TSH a thyroid hormone?

TSH is a hormone secreted by the pituitary gland that stimulates the thyroid. TRH from the hypothalamus, TSH from the pituitary, and T4/T3 from the thyroid form a negative feedback loop.

TSH itself is not a hormone produced by the thyroid, but it is a key indicator for evaluating thyroid function. When viewed alongside free T4, it is easier to understand which part of the axis has changed.

How does it affect basal metabolism?

Thyroid hormones act to increase oxygen consumption, heat production, and sodiumcellular energy use, such as the potassium pump. They also affect heart rate, intestinal motility, and the muscular and nervous systems.

If function is excessive, metabolism may speed up, and if it is deficient, it may slow down, but in reality Basal Metabolic Rateis Lean Body Mass, it is also influenced by age and other hormones.

What is the relationship with weight changes?

hypothyroidismweight may increase due to decreased energy expenditure, reduced activity, and changes in body fluids. hyperthyroidismweight loss and muscle wasting may occur even if appetite increases.

However, most general weight gain cannot be explained by the thyroid alone. Even after thyroid treatment, the effects of lifestyle and energy balancehabits remain.

What accompanying symptoms are observed?

In hypothyroidism, sensitivity to cold, constipation, fatigue, dry skin, slow heart rate, and menstrual changes may occur. In hyperthyroidism, sensitivity to heat, tremors, throbbing, diarrhea, anxiety, and decreased muscle strength may occur.

Symptoms are non-specific and overlap with other conditions or lack of sleep. Diagnosis is not made based on a list of symptoms alone.

In particular, palpitationsSince these can occur due to caffeine, medication, anxiety, and changes in heart rhythm in addition to thyroid problems, we review test results and medication lists together.

How is the test performed?

Generally, blood TSH and free T4 are used first, and depending on the situation, T3, thyroid autoantibodies, and imaging tests are added. Pregnancy, acute illness, and medications taken can affect the results.

Laboratory reference ranges are interpreted together with individual circumstances. Subtle differences within the normal range are not concluded to be the sole cause of weight plateau.

How do supplements and medications affect the condition?

Biotin supplements can interfere with some thyroid immunity tests, so you must inform your provider whether you are taking them before the test. Amiodarone, lithium, and iodine exposure can also affect thyroid function.

The absorption of prescribed thyroid hormones can vary depending on food, iron, calcium, and the interval between doses. Dosage and administration methods are adjusted with the prescribing medical staff.

Why is it dangerous to use them for weight loss?

If hormones are used in excess when thyroid function is normal, weight may decrease, but this can result in the loss of muscle and bone, not just fat. There are also risks of throbbing, arrhythmia, anxiety, and heat damage.

Be cautious that supplements claiming to increase metabolic rate do not contain thyroid-related ingredients. Do not use hormones without a diagnosis.

Signs that medical evaluation is needed

New severe throbbing, chest pain, fainting, high fever, and changes in consciousness require prompt medical evaluation. Severe lethargy, hypothermia, edema, and decreased consciousness can also be emergency situations.

If persistent weight changes overlap with thyroid symptoms, organize your list of medications, supplements, and the timing of onset before seeking medical evaluation. Do not arbitrarily stop or increase the dose of medication.

In what order are test results read?

First, we look at how TSH and free T4 are combined from the same blood draw, and check for pregnancy, acute illness, and the timing of thyroid medication intake. A TSH value outside the reference range does not immediately explain all weight changes, and there are cases where retesting is necessary.

During treatment, symptoms, test trends, medication adherence, and absorption interference are monitored together. Dosage is not changed based on a single T3 value or 'optimal ranges' found on the internet, but rather based on goals appropriate for the diagnosis type.

If weight has changed before and after treatment edema, we also look at appetite, activity, and muscle condition. Weight issues remaining after thyroid levels have normalized must be evaluated separately in terms of sleep, diet, and activity; they are not resolved by further increasing medication.

How much does weight return after treatment?

After treating hyperthyroidism, weight may increase as excessively high energy expenditure, appetite, and body water levels change. In the treatment of hypothyroidism, edema and some weight may decrease, but this does not mean all weight gain was due to the thyroid. It is difficult to predict exactly if weight will return to pre-treatment levels.

Once test values have stabilized, the effects of diet, activity, sleep, and other medications are examined separately. Arbitrarily increasing or decreasing thyroid medication due to weight changes can be harmful to the heart, bones, and overall systemic health.

Can medication be changed based on a single change in TSH?

TSH can take time to stabilize after a change, and the timing of blood collection, acute illnesses, and medication adherence also affect the interpretation. Weight issues are not confirmed, nor is the dosage changed to match internet targets, based on a single result that is slightly outside the reference range.

Prescribing clinicians consider the type of diagnosis, free T4, symptoms, pregnancy status, and previous result trends. If you missed a dose or the timing of your medication changed, you must disclose this so that tests and dosages can be interpreted correctly.

Thyroid information to prepare before a weight consultation

Prepare the exact diagnosis, history of surgery or radioactive iodine treatment, recent TSH and free T4 results, and the dates of those tests. Also, note the medication name, dosage, and time of administration, as well as supplements such as iron, calcium, or biotin, and current symptoms like throbbing, tremors, sensitivity to cold, or constipation.

If you do not have the results, do not try to recall the numbers from memory; instead, check the timing of the test and the medication packaging. If you experience chest pain, fainting, severe shortness of breath, high fever, or changes in consciousness, seek immediate emergency evaluation rather than waiting for a weight consultation or your next appointment. resting metabolic rate Estimates are not a substitute for thyroid tests.