From TSH to TPO: Exploring the full picture of thyroid function

The thyroid gland, a small butterfly-shaped organ located at the base of your neck, plays a crucial role in your body's overall functioning. This tiny powerhouse produces hormones that help regulate your metabolism, heart rate, body temperature, mood and more. When your thyroid isn't functioning properly, it can cause a variety of symptoms that may be easily overlooked or misdiagnosed. If you want to better understand your thyroid health and function, there are several testing options available to help you gain insight into this important gland.

General thyroid function and thyroid hormone screening

Did you know that more than 12% of the U.S. population will develop a thyroid condition during their lifetime? Even more surprising is that up to 60% of those with thyroid disease are unaware of their condition. Undiagnosed thyroid disease may put you at risk for certain health conditions such as heart disease, osteoporosis and infertility.  The American Thyroid Association recommends that adults, especially women and those with risk factors, consider thyroid screening starting at age 35, with follow-up testing every five years or as recommended by a healthcare provider.

For general thyroid function and thyroid hormone screening, a thyroid stimulating hormone (TSH) test can provide valuable insights. TSH is a hormone produced by the pituitary gland that stimulates the thyroid gland to produce T4 (thyroxine) and T3 (triiodothyronine). These hormones help regulate the body's metabolism, which is responsible for how the body converts food into energy, maintains body temperature and controls various functions such as heart rate and muscle control. When these thyroid hormones become imbalanced, they may cause health issues ranging from irregular heartbeat to depression.

Screening for underactive or overactive thyroid

Two common thyroid conditions are underactive thyroid (hypothyroidism) and overactive thyroid (hyperthyroidism). An underactive thyroid doesn't make enough thyroid hormones, primarily T3 and T4, while an overactive thyroid produces more thyroid hormones than your body needs. Both conditions affect how your cells use energy, which can lead to a range of symptoms.

Hypothyroidism symptoms can include:

• Dry skin and hair
• Constipation
• Muscle cramps
• Heavy periods
• Impaired memory and concentration
• An enlarged thyroid gland

On the other hand, hyperthyroidism symptoms may include:

• Trembling hands
• Sweating
• Diarrhea
• Muscle weakness
• Irregular periods

If you're experiencing symptoms that you think may be related to your thyroid health, consider checking your thyroid hormone levels with Labcorp OnDemand’s Standard Thyroid Test. This test measures TSH and free T4, which can help screen for potential thyroid imbalances such as hypothyroidism or hyperthyroidism. However, a full diagnosis should be made by a healthcare provider.

Learning more about your energy and metabolism

Testing certain thyroid hormones, such as free T3, can help provide information about your metabolic health. While measuring thyroid hormones like free T3 can provide a partial assessment of thyroid function, this hormone is often evaluated in the context of other thyroid function tests, such as TSH or free T4, to gain a full picture of thyroid health.

Measuring free T3 levels with Labcorp OnDemand’s Free T3 Test can provide additional information about your thyroid function. Elevated free T3 levels may indicate an overactive thyroid, which can cause symptoms like irregular heartbeat, weight loss, anxiety and fatigue.

Screening for autoimmune conditions and thyroid disorders

Autoimmune thyroid disease happens when your body makes antibodies that attack the cells in your thyroid. For example, thyroid peroxidase (TPO) antibodies mistakenly attack the thyroid gland in Hashimoto's thyroid disease. Elevated TPO antibodies are more commonly associated with Hashimoto's thyroiditis, which causes hypothyroidism (an underactive thyroid), but they can also be present in Graves' disease, which leads to hyperthyroidism (an overactive thyroid).

Symptoms of Hashimoto's can include:

• Fatigue
• Weight gain
• Constipation
• Dry skin
• Muscle aches
• Irregular periods
• Depression
• Increased sensitivity to cold

Symptoms of Graves' disease may include:

• Racing heartbeat
• Tremors
• Trouble sleeping
• Weight loss
• Muscle weakness
• Heat intolerance
• Swelling of the eyes

Having TPO antibodies in the blood does not always mean there is a thyroid disease. Many healthy people, especially women and older adults, can have TPO antibodies without any symptoms or thyroid problems.

Detecting TPO antibodies can help you and your healthcare provider make informed decisions about your health. It's important to note that TPO antibody levels are often evaluated in the context of other thyroid function tests, such as TSH, free T4 and free T3, to gain a full picture of thyroid health. Testing TPO antibodies alone cannot assess thyroid function.

Taking charge of your thyroid health

Understanding your thyroid function is an important step in maintaining your overall health. It's crucial to work closely with a healthcare provider to discuss your thyroid health, including any symptoms you may be having that could be related to thyroid function, and possible testing options to help check your thyroid. Your healthcare provider can help determine what type of thyroid testing is right for you and help you understand your results and next steps. By staying informed and proactive about your thyroid health, you can take an active role in managing your overall well-being.