TSH Normal Range

The amount of measurement of thyroid stimulating hormone (TSH) in blood is done by a laboratory blood test called a TSH test. The pituitary gland produces TSH (or thyroid stimulating hormone). In general, it modulates the thyroid gland to produce and secrete thyroid hormones into the blood. Many doctors consider the TSH blood test to diagnose and treat both imbalances of the thyroid hormone like overactive (hyperthyroidism) or under active (hypothyroidism)thyroid.

Purpose of TSH test

TSH test is performed to determine the imbalance of thyroid hormone. It is done to diagnose and treat either an under active or overactive thyroid gland. The treatment outcome can also be determined by obtaining TSH test reports.

Normal TSH Values  

The normal range of TSH test report can range from between 0.4 – 4.0 milli-international units per liter. The TSH value depends on various factors like lab reports, related symptoms and treatment for the condition. It is advised to get closely monitored by a physician despite absence of signs or symptoms associated with hypothyroidism (under active thyroid) or if TSH value is more than 3.5 mIU/L with normal T4 test value (which indicates subclinical hypothyroidism).

Patients undergoing treatment for a thyroid disorder should have their TSH level ranging from between 0.5 and 2.0 mIU/L. These values represent the common measurements for the above mentioned conditions. Each laboratory can consider TSH values that are slightly variable from a normal TSH range. Different laboratories follow different test samples or consider different measurements and hence, the value is specific for each laboratory. One can discuss with their physician to learn about the specific test results.

Abnormal TSH reports

TSH levels that are higher than normal can clinically signify hypothyroidism (or under active thyroid gland). Moreover, it could be due to a variety of causes. TSH levels that are lower than normal can represent hyperthyroidism (or overactive thyroid gland) or could be caused by various other conditions like Toxic nodular goiter, graves disease, and intake of certain drugs such as opioid painkillers(morphine), steroids or gluco corticoids.

Pathology behind abnormal TSH

The TSH levels in blood are measured by a TSH test. In general, the pituitary gland produces and secretes TSH. The pituitary gland detects thyroid hormone levels in the blood circulation, and it secretes excess of TSH in case of insufficient availability of thyroid hormone. TSH basically stimulates thyroid gland to secrete more amount of hormone and hence, the levels of TSH increase in case of under active thyroid. In addition, increased TSH levels also indicate excess hormone production by the pituitary gland in an effort to stimulate the thyroid gland to function properly and to release sufficient thyroid hormone

In contrary, the pituitary gland either slows down or ceases the release of TSH in case of high levels of thyroid hormone in the blood stream. Reduced TSH level also indicates that the thyroid gland is no longer stimulated to release hormone and hence, the rate of production of thyroid hormone drastically slows down.

Old normal TSH Range

Many expert physicians in the United States rely on TSH test results to diagnose and treat thyroid associated conditions like hypothyroidism or hyperthyroidism. However, they do not follow a specific TSH value interpretation. The official normal range of TSH followed by many doctors and laboratories until 2002 was from between 0.5 to 5. According to this TSH range, a TSH over 5 indicated an under active thyroid (or hypothyroidism); while a low TSH value below0.5 indicated an overactive thyroid or (hyperthyroidism).

Newly approved normal TSH range

The American Association of Clinical Endocrinologists (AACE) and other professional associations, in the late 2002 have recently approved a narrow TSH range from between0.3 to 3. This indicates that low TSH levels below 0.3 indicate hyperthyroidism; whereas, a higher TSH value of 3 and above 3 confirmed the diagnosis of hypothyroidism.

Currently recommended TSH range

Majority of medical laboratories in the United States currently refer the old approved TSH range from 0.5 to 5 as the normal TSH reference range in all their test reports. To be more specific, obtaining the TSH reports ranging from 5 and 0.5 will still not be flagged as abnormal.The newly recommended TSH reference range is not followed by physicians who aren’t aware of new guidelines or those who consider lab results that are flagged as low or abnormal or high values.

In contrary, some doctors prefer to not follow the latest, recommended guidelines as they refrain from diagnosing hypothyroidism in cases with a TSH level ranging from between 3.0 to 5. Similarly, they don’t diagnose hyperthyroidism, either, in cases presenting a range of 0.3 and 0.5. To be more specific, normal TSH can range from between 0.3 to 5. For instance, a person with a TSH range of 4.5 is considered normal by one physician, where as another physician can diagnose it as hypothyroidism and begin with the treatment.

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