How to Test for Thyroid Disorders: FAQ Guide

Published March 19, 2025

This guide covers key information about how to get tested for thyroid disorders, including symptoms, available tests, and how to interpret results.

The thyroid is a small but essential gland in the neck that regulates metabolism, energy levels, and overall body function. An estimated 20 million people in the United States have thyroid disease. But up to 60% of the people who have thyroid disease are not aware.² That’s why thyroid function testing by measuring thyroid-stimulating hormone (TSH) is so important. 

What Are the Symptoms and Risks of Thyroid Disorders?

Thyroid disorders generally fall into two categories: hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). Each condition presents different symptoms and health risks.

Symptoms of Hypothyroidism (Underactive Thyroid)

• Fatigue
• Weight gain
• Depression
• Dry skin
• Sensitivity to cold
• Slow heart rate
• Constipation
• Memory issues¹,²
• Thinning hair
• Enlarged thyroid gland (goiter)
• Muscle aches and pains
• Joint pain and stiffness
• Depression
• Muscle weakness
• Facial puffiness
• Hoarseness

Who Is at Risk for Hypothyroidism?

• Individuals with a family history of thyroid disease
• Those over the age of 60
• People with autoimmune conditions such as lupus or rheumatoid arthritis
• Individuals who have received radiation therapy to the head or neck³

Symptoms of Hyperthyroidism (Overactive Thyroid)

• Unexplained weight loss
• Increased appetite
• Rapid or irregular heartbeat
• Palpitations—a fluttering or pounding heartbeat
• Anxiety or nervousness
• Sensitivity to heat
• Increased sweating
• Trouble sleeping
• Brittle or fine hair
• Muscle weakness⁴,⁵
• More frequent bowel movements
• Sweating

Who Is at Risk for Hyperthyroidism?

• Individuals with a family history of thyroid disorders
• Those with autoimmune conditions such as Graves' disease
• Women, particularly after pregnancy or menopause
• Individuals with excessive iodine intake⁵

What Tests Check for Thyroid Problems?

There are several blood tests help assess thyroid function:

TSH (Thyroid-Stimulating Hormone) Test

• Measures TSH levels to evaluate thyroid function
• High TSH may indicate hypothyroidism; low TSH may indicate hyperthyroidism

T4 (Thyroxine) Test

• Measures the thyroid hormone T4
• Free T4 testing is considered more accurate than total T4

T3 (Triiodothyronine) Test

• Measures T3 hormone levels
• Free T3 testing is often used when hyperthyroidism is suspected

Thyroid Antibodies Test

• Detects autoimmune thyroid conditions such as Hashimoto’s thyroiditis or Graves' disease

How Should You Prepare for a Thyroid Test?

• No fasting is required for thyroid function tests
• Certain medications can impact results, including biotin supplements and thyroid hormone replacement therapy
• Inform your healthcare provider of any medications before testing

How to Read Thyroid Test Results

Your test results may not always be straightforward. You should work with your healthcare provider to interpret your individual results in combination with your health history. 

Possible Thyroid Blood Test Results:

• High TSH: May indicate hypothyroidism (underactive thyroid)
• Low TSH: May indicate hyperthyroidism (overactive thyroid)
• Abnormal T4 or T3 Levels: Can provide further insight into thyroid function and possible underlying conditions⁷

If your test results indicate thyroid dysfunction, your healthcare provider may recommend additional testing, such as a thyroid ultrasound or a radioactive iodine uptake test, to determine the cause.

Why Choose Quest for Thyroid Testing?

Quest Diagnostics offers fast and reliable thyroid testing with several key benefits:

• No doctor’s visit required—order online and visit a nearby Quest location.
• Accurate and comprehensive testing with automatic free T4 follow-up when needed.
• Independent physician consultations available at no extra cost for abnormal results.

Buy Your Thyroid Test Today

No doctor visit is required to buy your own lab test at questhealth.com. PWNHealth and its affiliates review your purchase to ensure it is medically appropriate before submitting the test order for processing. PWNHealth also reviews your test results and will contact you directly if they require prompt attention. Included in each purchase is the option to discuss your test results with an independent physician; however, you are also encouraged to speak with your primary healthcare provider.