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Although normal aging is inevitable and may look different to everyone, certain outer characteristics like gray hair and wrinkles can make aging feel more visible. Most people don't consider the internal changes affecting their thoughts and feelings until they affect them directly. 

This article will look at how your thyroid function and potential risk factors associated with aging. 

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Your endocrine system consists of organs and tissues that make hormones. Once produced, hormones enter your bloodstream. They travel to other organs, where they are responsible for the actions and functions of that organs. Estrogen, testosterone, and insulin are a few examples of hormones.

As you age, your body systems change. For the endocrine system, these changes could include:

• Decrease in hormone sensitivity at the target organ, meaning the same amount of hormone will have less of an effect
• Increase or decrease in hormone production
• Physical changes to glands

Let’s take a closer look at one of those hormones made by your endocrine system.

Your thyroid gland, a butterfly-shaped organ at the base of your neck, makes thyroid hormone. The thyroid hormone has many important roles in our body, including:

• Growth and development
• Regulation of body temperature and metabolism
• Digestion
• Hair, nail, and skin health
• Fertility
• Mental health

As you can see, thyroid hormone production is essential for your cells and organs to function. But how does your body know how much to make?

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The hypothalamus-thyroid feedback loop regulates the production of thyroid hormone.

Your hypothalamus, located in your brain, releases thyrotropin-releasing hormone (TRH). This tells your pituitary gland to release thyroid-stimulating hormone (TSH) which signals your thyroid gland to release triiodothyronine (T3) and thyroxine (T4). Once released, they travel to their target organs, where T4 is converted to T3, the active form of thyroid hormone. As your levels of T3 and T4 decrease, your hypothalamus releases TRH and the loop continues.

A disruption to this cycle changes the balance of these hormones. Since these hormones circulate in your blood, it is easy to see when these levels are outside the normal range.

Your thyroid hormone levels and especially TSH, can increase or decrease throughout your life. Some factors that influence these changes include:

• Periods of growth and development
• Your genes
• Pregnancy
• Mild Iodine deficiency
• Environmental factors like seasonal or temperature changes
• Tobacco smoking status
• Medications such as lithium, amiodarone, or metformin
• Ethnicity
• Gender

After birth, TSH levels surge followed by an increase in T4 levels within the first day of life. TSH levels will remain higher than those seen in adults but slowly fall. Around 6 to 9 months of age, TSH reaches a certain level and stays there through childhood while free T4 gradually falls. On the contrary, T3 levels are low at birth but gradually increase.

During adolescence, a period of growth and development, TSH and free T4 levels vary based on gender and age. For instance, males had a higher TSH than females between the ages of 12 and 14. But males and females both have an increase in TSH between ages 14 and 16.

Studies show that free T4 increases in both genders from age 14 to 16, while free T3 decreases around 16.

Your metabolism starts to slow down around the age of 20. This doesn’t mean that your thyroid hormone has drastically decreased, causing overt hypothyroidism. Your TSH does start increasing around the third decade of life. One study found there was an average increase of 13% in TSH levels and a 1.7% increase in free T4 over a 13 year timeframe on men with an average of 85 years old. One study showed that about 3 to 16% of those older than 60 have subclinical thyroid dysfunction or subclinical hypothyroidism.

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However, not all studies show that T4 increases as we age. 

Subclinical hypothyroidism

In subclinical hypothyroidism, T4 is normal with an elevated TSH. Symptoms are not always present in subclinical hypothyroidism. However, it can be hard to tell if symptoms are from hypothyroidism or the natural aging process. Symptoms of overt hypothyroidism include:

• Fatigue

• Dry skin

• Cold intolerance

• Weight gain

• Muscle and joint aches and pain

• Hoarse voice
• Cognitive impairment

Mild subclinical hypothyroidism doesn’t appear to have a health impact on older individuals or cognitive impairment, however, working with a thyroid specialist can help you understand your treatment options.

Testing your thyroid hormone levels is easy with our Paloma at-home test kit. Mail a finger-prick blood sample to the lab and have your results for TSH, free T3 and T4, and TPO antibodies within 3 to 5 days. Make sure to schedule a virtual appointment with one of our thyroid doctors to help interrupt your results and come up with the next steps.

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