Thyroid TSH Function Test

What

This test measures the level of thyroid stimulating hormone, or TSH, in your blood. If your TSH level is abnormal, your sample will be further tested at no cost to you to help evaluate for a thyroid disorder.

Treatment options may be available. See "After the Test" section.

Who

Must be 18+ years of age to purchase

Orders not permitted in: AK, HI, AZ

How

Type of samples to be collected:
Blood (venipuncture—a needle is used to draw blood from a vein)

This test features additional testing, see ‘Reflex’ section for details.

Where

Find a location near you

Schedule an appointment, then visit one of our Patient Service Centers.

About the Test

The Thyroid Function Test measures the level of TSH in your blood to help determine that your thyroid gland is functioning properly. Noticeable changes in your metabolism (weight, temperature, and energy) may be a sign or symptom that there is too much or too little TSH in your blood. If TSH levels are too high or too low, this may indicate that your thyroid is overactive (hyperthyroidism) or underactive (hypothyroidism). In either case, T4 blood levels will be evaluated, at no additional cost, to help evaluate a possible thyroid disorder (including hyperthyroidism and hypothyroidism).

The thyroid is a butterfly-shaped gland in the front of the neck. Thyroid function is controlled by the pituitary gland, which produces TSH and releases it into the bloodstream. TSH stimulates the thyroid gland to produce thyroid hormones (T3 and T4). TSH will also tell the body to make or release thyroid hormones. This process determines how quickly your body uses energy, makes proteins, and controls other important functions, such as:

Body temperature
Heart rate
Breathing
Skin moisture
Muscle contraction
Weight gain or loss
Brain development
Cholesterol levels
Menstruation
Nervous system function

The thyroid function test measures the level of TSH in the blood to help evaluate thyroid function. The pituitary gland detects thyroid hormones in the blood. If the thyroid is making a lot of these hormones, the pituitary will stop producing TSH, leading to low levels of TSH. Low TSH may mean the thyroid gland is overactive, commonly referred to as hyperthyroidism. High levels of TSH in the blood may indicate the thyroid gland is not working hard enough, causing the pituitary to keep making TSH. High TSH can indicate an underactive thyroid gland, commonly referred to as hypothyroidism. Both conditions may require medical treatment.

Thyroid disorders can affect any system of your body and treatment will depend on the specific thyroid condition. An undiagnosed thyroid disorder may put you at risk for cardiovascular diseases, osteoporosis, infertility, and other serious conditions; most thyroid conditions can be managed with medication.

Symptoms of thyroid disorders can be mild, moderate, or severe and often resemble other medical conditions. You may consider getting a thyroid function test if you're experiencing the following symptoms:

Hypothyroidism (underactive thyroid) symptoms can include:

Weight gain
Fatigue
Increased sensitivity to cold
Thinning hair
Enlarged thyroid gland (goiter)
Muscle aches and pains
Joint pain and stiffness
Elevated cholesterol levels
Constipation
Depression
Problems with memory
Slower than normal heart rate
Dry skin
Muscle weakness
Facial puffiness
Hoarseness

Hyperthyroid (overactive thyroid) symptoms can include:

Increased appetite
Irregular heartbeat
Palpitations—a fluttering or pounding heartbeat
Unintentional weight loss
More frequent bowel movements
Anxiety or nervousness
Sweating

The Thyroid Function Test is for anyone who wants to know whether their thyroid is working properly or who is concerned that they may be at risk for a thyroid disorder. You must be 18 years old to purchase.

You do not need to do anything special to prepare for the sample collection. Fasting is not required for this test.

When your results are ready, we will send them to you in a clear, easy-to-read report.

You will have the option to speak with an independent physician to discuss your results.

Together, you and your physician may develop a personalized treatment plan that best supports your thyroid health.

If a medication is prescribed, it will be sent by the physician to the pharmacy of your choice*.

*Treatment is currently only available to those over age 18 with high TSH levels (Hypothyroidism)

If thyroid (TSH) is abnormal, T4 is also performed on the sample you have already provided.

How Does it Work?

Take an in-person test at a Quest Diagnostics location.

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Schedule your appointment after purchasing a test to minimize wait time.

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Take control of your health

Conveniently shop and pay online for lab tests without a doctor's visit. An independent physician will review your request and if appropriate, confirm your order and offer oversight.

Schedule and manage your appointments

Conveniently schedule your appointment online at one of our Quest Diagnostics locations. Certain tests may also offer self-testing home delivery.

Get your results online

View your results through your secure account online. And it's easy to share the result with your doctor.

Your results are available on our free, secure patient portal that you can access on your smartphone, tablet, or desktop. You will receive an email notification when your results are ready. You can also share your results with your doctor, family, or friends.

FAQs

How common is hypothyroidism?

About 5 percent of Americans who are 12 years old or older have hypothyroidism. Many people who have hypothyroidism are unaware.

Which thyroid disorder is most common, hypothyroidism or hyperthyroidism?

Hypothyroidism is more common.

How often should I have my thyroid function checked?

Currently, there is no evidence to support routine screening of your thyroid function. You may consider checking your thyroid function if you are having symptoms of a thyroid disorder or if you are at high risk for developing a thyroid disease.

If you have been diagnosed with a thyroid disorder, you may have your thyroid function checked more frequently. Consult with your healthcare provider to determine a longer-term care plan.

Are there risk factors to be aware of for developing thyroid disease?

Even if you don’t have symptoms, you may consider testing if you have the following risk factors:

• Family history of thyroid disease
• Women
• People over age 50
• Have an autoimmune disease such as type 1 diabetes
• History of thyroid surgery
• Radiation treatment for a past thyroid condition
• Recent pregnancy
• Taking medication high in iodine

Who is getting tested? *

Test Type