The Chemistry of the Thyroid


The thyroid is a butterfly shaped gland located in front of the throat. The two sides, called lobes, are connected by tissue called the isthmus. The gland secretes hormones to help regulate systems in the body such as metabolic rate, heart rate, blood pressure, central and peripheral nervous systems, body weight, muscle strength, menstrual cycles, body temperature, and cholesterol levels. I chose the chemistry of the thyroid because for many years I have had problems with my thyroid that doctors can’t explain. So, I decided to learn about it for myself. Every person depends on their thyroid for many reasons. If it’s under-active ( Hypothyroidism), one may face fatigue, increased sensitivity to cold, constipation, dry skin, weight gain, puffy face, hoarseness, muscle weakness, elevated blood cholesterol level, muscle aches, tenderness and stiffness, heavier than normal or irregular menstrual periods, thinning hair, slowed heart rate, depression, and even impaired memory. This is what I experienced. On the other hand, if the thyroid is overactive (hyperthyroidism) one will undergo sudden weight loss, rapid heartbeat, increased appetite, nervousness, anxiety and irritability, tremor, changes in menstrual patterns, increased sensitivity to heat, fatigue, Difficulty sleeping, skin thinning, fine, brittle hair.

Composition of ...

    • T3- C15 H12 I3 N O4
    • T4 - C15 H11 I4 N O4
    • Calcitonin- C151 H228 N40 O45 S3
    • Tyrosine- C9 H11 N O3
    • Thyroglobulin- C15 H10 I4 N Na O4

Main Chemicals, Compounds, Components

The thyroid produces three chemicals. Tetraiodothyronine, also called thyroxine or T4 (C15 H11 I4 N O4); Triiodothyronine or T3 (C15 H12 I3 N O4); and Calcitonin(C151 H228 N40 O45 S3). The hormones are derivatives of the Amino acid tyrosine covalently bonded to iodine. The thyroid is composed of follicles, spherical cells that absorb iodine. Thyroglobulin is used to store the iodine in the cell. Follicular cells surround the follicles and secrete T3 and T4. The parafollicular cells release calcitonin. T4 is the main chemical involved in sustaining the thyroid’s functions.

Chemistry's Role

The thyroid is part of endocrine system. This includes glands such as the hypothalamus and the pituitary gland. The hypothalamus controls the thyroid. When the thyroid’s hormone levels drop too low, the hypothalamus releases TSH Releasing hormone (TRH). TRH tells the pituitary gland to produce Thyroid stimulating hormone (TSH). The TSH tells the thyroid to produce T4, T3 and Calcitonin. These hormones are water soluble, so they bond with iodine to travel through the blood. The hormones increase oxygen to the brain which in turn regulates heart rate, metabolic rate, blood pressure and many more listed above.

Background Research

The thyroid was discovered by Geoffrey Websterson in 1664. To this day, hundreds of discoveries have been made about the thyroid. When developing as a fetus, it is located at the base of the tongue and migrates down the throat. In some cases, the thyroid will travel too far or not far enough, causing complications such as gout ( an inflamed or enlarged thyroid).


what T4, T3 and Calcitonin are

effects of inactive or overactive thyroid

how the hormones affect the body

composition of cells

in depth on hormones

chemical formulas

Background and discovery

composition and use of cells

In depth on chemicals


uses of compounds

About the Author

Cierra Coppock is a junior at Billings Senior High. She has played soccer for 11 years, but is often hindered by constant injury and illness. After countless doctors visits, they finally came to the conclusion that something was wrong with her thyroid. Cierra is determined to find the cause and resolve this issue before her senior year so she can continue her career in soccer.