Contributed by – Healthians Team
What is the TSH ultrasensitive test?
A TSH ultrasensitive test is a primary screening test done to find out if your thyroid gland is working the way it should. It can tell you if you have an overactive (hyperthyroidism) or underactive (hypothyroidism) thyroid. In short, this test will determine the general health of your thyroid gland and how well it is functioning. This test can detect a thyroid disorder before you have any symptoms. If untreated, a thyroid disorder can cause many health problems. Diagnosing thyroid disorder early on is an essential part of putting you on a successful treatment path.
Almost all laboratories currently use ‘third generation’ or ‘ultrasensitive’ TSH assays that provide a tenfold improvement in sensitivity over the original tests (immunoassays) for TSH.
TSH stands for ‘thyroid-stimulating hormone’ and the test measures the proportion of this hormone in your blood. TSH is secreted from the pituitary gland in your brain. This gland triggers your thyroid to make and release the thyroid hormones into your blood.
Who should get the TSH ultrasensitive test?
The TSH blood test is often administered as part of a panel of routine preventive care tests in conjunction with an annual health exam. Your doctor may order a TSH test if they see suggestive symptoms and physical findings that suggest your levels are either too high or too low.
Overactive Thyroid (hyperthyroidism) Symptoms and Signs
- Sweating
- Increased appetite
- Increased sensitivity to heat
- Thinning hair
- Tremors
- Muscle weakness
- Anxiety
- Irritability
- Racing heartbeats
Underactive Thyroid (hypothyroidism) Symptoms and Signs
- Extreme fatigue
- Brain fog
- Dry skin
- Hair fall
- Feeling cold
- Weight gain
- Fertility problems
- Hoarseness in voice
Why is the TSH ultrasensitive test needed?
A TSH test may be needed in the diagnosis of two fairly common medical conditions:
- Hyperthyroidism, a disorder which involves having too much of the thyroid hormone in your blood.
- Hypothyroidism, a disorder which involves having too little of the thyroid hormone in your blood.
The test also screens for other diseases like an enlarged thyroid, which is called a goiter, or thyroid nodules, which are small lumps on the thyroid gland.
What does the TSH ultrasensitive test result mean?
Most laboratories classify normal TSH levels as between 0.4 milliunits per liter (mU/L) to 4.0 mU/L.
A Higher than the normal range of thyroid hormones
Generally, TSH levels above 4.5 mU/L indicate an underactive thyroid. It is also known as hypothyroidism, meaning your body is not making adequate thyroid hormone.
A Lower than the normal range of thyroid hormones
TSH levels less than 0.4 mU/L indicate an overactive thyroid. It is also known as hyperthyroidism meaning, your body produces too much thyroid hormone.
| T3 | T4 | TSH | |
| Normal Thyroid | Normal | Normal | Normal |
| Hyperthyroidism | High | High or Normal | Low |
| Hypothyroidism | Low or Normal | Low | High |
Table 1: Patterns of thyroid function tests during an assessment of thyroid function
How is the TSH ultrasensitive test done?
TSH testing is a simple non-fasting blood test. The best time to give your blood sample is in the morning, as TSH levels fluctuate with the time of the day. Certain medications can impact your TSH levels, so it is important to tell your doctor if you are taking any over-the-counter drugs, prescription medications, or herbal supplements. If you are consuming a high dose biotin therapy or a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R), the sample should be collected at least 8 hours after the last dose.
The most important message to take away from this is that the TSH that is too high or too low may become problematic. So it is recommended to ensure that your TSH levels (and ideally, T4 and T3) are not only the ‘normal’ range but also within an optimal range for your personal health and well-being.
