Sage-Tips

What does normal TSH and low free T4 mean?

A normal TSH and normal T4 show a normal thyroid. A low TSH and high T4 generally means an overactive thyroid. A high TSH and low T4 means an underactive thyroid. A low TSH and low T4 mean low thyroid function because of another problem, such as with the pituitary gland or hypothalamus of the brain.

What causes low T4 and normal TSH?

If the pituitary fails to make enough TSH then free T4 levels in the blood will fall – but since the problem is at pituitary level then TSH levels in the blood do not rise appropriately. In severe cases free T4 will fall below the normal range, while TSH levels can be normal or low (see diagram).

Can you still have hypothyroidism with normal TSH levels?

While you may be told that TSH levels of 1 to 2 mU/L are “fine” if you have mild hypothyroidism, it is possible to still have symptoms, especially if your levels tend to fluctuate.

What is more accurate TSH or T4?

“Since small changes in T4 and T3 would be reflected by much larger, exponential changes in TSH, the TSH is thought to be a more accurate marker and earlier signal of potential thyroid status abnormalities.

What TSH level is considered hypothyroidism?

TSH > 4.0/mU/L with a low T4 level indicates hypothyroidism. If your TSH is > 4.0 mU/L and your T4 level is normal, this may prompt your physician to test your serum anti-thyroid peroxidase (anti-TPO) antibodies.

What is the treatment for low T4?

If you have hypothyroidism, your doctor will prescribe a synthetic (human-made) thyroid hormone T4. You take this pill every day. Certain other medications can interfere with how your body absorbs synthetic thyroid hormone.

What are the symptoms of low T4?

Symptoms of hypothyroidism, also known as underactive thyroid, include:

• Weight gain.
• Fatigue.
• Hair loss.
• Low tolerance for cold temperatures.
• Irregular menstrual periods.
• Constipation.

Can you have hypothyroidism with normal T4?

A high level of TSH and a low level of T4 in the blood could mean you have an underactive thyroid. If your test results show raised TSH but normal T4, you may be at risk of developing an underactive thyroid in the future.

What T4 levels indicate hypothyroidism?

Is it better to ask for TSH or T4 for thyroid evaluation?

In these situations, it is better to ask both for TSH and free T4 for thyroid evaluation, which will typically be in the normal range. Biotin, a commonly taken over-the-counter supplement, can cause the measurement of several thyroid function tests to appear abnormal, when they are in fact normal in the blood.

How do you know if your TSH is high or low?

If TSH is high, we confirm low thyroid function with a test called free or unbound T4 (T4 in the bloodstream that is not attached to a protein). It may help to think of the pituitary gland as a thermostat and the thyroid gland as a heater.

What does a low TSH level with an elevated FT4 mean?

A low TSH with an elevated FT4 or FTI is found in individuals who have hyperthyroidism. T3 tests are often useful to diagnosis hyperthyroidism or to determine the severity of the hyperthyroidism. Patients who are hyperthyroid will have an elevated T3 level. In some individuals with a low TSH, only the T3 is elevated and the FT4 or FTI is normal.

What is a normal TSH level for a thyroid patient?

What is a Normal and Healthy TSH Level for Thyroid Patients? A healthy TSH level for people taking thyroid medication is much different from those people who are checking to see if they have thyroid problems initially. A healthy TSH level is somewhere in the range of 0.2 to 2.5 .