Thyroid Part I: Function

---

Introduction

The Thyroid is considered to be the general of our endocrine system. It controls hormonal activity, sets the pace for our metabolism, and dictates major biological processes in the body. If our Thyroid is sluggish, we are sluggish. Here is a small list of the signs and symptoms of a low functioning Thyroid:

• Cold hands and feet
• Dry, flaky skin
• Soft, brittle fingernails
• Cracking of the heels or hands
• Overemotional – cry for no reason
• Thinning or balding of the hair, especially the lateral 1/3 (outside) of the eyebrows
• Frequent infections
• Puffy upper eyelids
• Inability to lose weight
• Low sex drive
• PMS
• Fatigue, worse in the morning
• “Foggy” thinking
• Loss of memory
• Depression
• Morning axillary (armpit) temperature below 97.8

---

Biologoical Pathway

Let us discuss what the Thyroid actually does and how the entire process works from start to finish. Thyroid function is one of our body’s greatest examples of self-regulation through the use of feedback loops. These feedback loops are meant to optimize the performance of the Thyroid and determine how active or inactive it is. This process begins when the Hypothalamus in our brain is relayed information that our Thyroid hormone (TH) is low in the form of Thyroxine (T4) and Triiodothyronine (T3). This stimulates the Hypothalamus to release Thyroid Releasing Hormone (TRH) which travels to the Pituitary gland and causes it to release Thyroid Stimulating Hormone (TSH). TSH is what initiates the process for the Thyroid to produce T4 and T3 through the use of Thyroglobulin, Iodine, Tyrosine, and many other cofactors. T4 is considered to be the inactive form of Thyroid Hormone while T3 is considered to be the active form. The production of adequate amounts of T3 is ultimately what we are trying to achieve with a healthy Thyroid. An important step in this cycle is when T4 is converted into T3 through a process called Deiodination. 60% of Deiodination occurs in the Liver (important) while 40% occurs in one of either the Kidney, GI tract, or peripheral tissue. Once the Hypothalamus is satisfied with the amount of Thyroid Hormone that is present in the body, it downregulates the cycle by throttling the release of TRH, thus halting the Pituitary’s production of TSH, and therefore stopping the activity of the Thyroid by discontinuing the production of Thyroid Hormone (T4 and T3). Once enough Thyroid Hormone is used and levels dip low enough so that more is needed, the cycle begins all over again and on and on it goes. As we can see there are some major players involved in this process including the Hypothalamus, Pituitary, Liver, Kidney, GI tract, and the Thyroid itself. If there is a kink in the chain at any level of production, Thyroid health will be jeopardized, and the overall wellbeing of the person will decline.

---

Read Part II.