THYROID STIMULATING HORMONE(ULTRASENSITIVE TSH),SERUM

Thyroid Stimulating Hormone (Ultrasensitive TSH), Serum

What it is

The Thyroid Stimulating Hormone (Ultrasensitive TSH), Serum test measures the concentration of TSH in the blood with high sensitivity. TSH is produced by the pituitary gland and regulates thyroid function by stimulating the thyroid gland to produce hormones thyroxine (T4) and triiodothyronine (T3). The ultrasensitive version of the test (3rd generation TSH) can detect very low levels, making it the gold standard for diagnosing subtle thyroid imbalances.

Uses

This test is primarily used to evaluate thyroid function and diagnose thyroid disorders such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). It is also used to monitor patients receiving thyroid replacement therapy or those on treatment for hyperthyroidism. Because it is ultrasensitive, it can detect even early or mild thyroid dysfunction before symptoms become obvious.

Symptoms That May Lead to the Test

Doctors may recommend this test if you show symptoms of thyroid imbalance. For hypothyroidism: fatigue, weight gain, constipation, hair loss, cold intolerance, or depression. For hyperthyroidism: rapid heartbeat, weight loss, sweating, heat intolerance, anxiety, irritability, or tremors.

Abnormal Results

High TSH Levels: Typically indicate hypothyroidism (thyroid underactivity) or inadequate thyroid hormone replacement. May also occur in pituitary disorders.

Low TSH Levels: Suggest hyperthyroidism (thyroid overactivity), excessive thyroid hormone medication, or pituitary dysfunction.

Normal Ranges: The reference range is usually 0.4–4.0 mIU/L, but it may vary slightly depending on the lab and clinical context.

Risks

The test requires a standard blood draw. Risks are minimal, such as mild pain, bruising, or temporary dizziness. There are no long-term risks associated with this procedure.