What is the Difference Between PTH and TSH

The key difference between PTH and TSH is that PTH is a peptide hormone secreted by the parathyroid gland that regulates serum calcium ion concentration through its effect on bone, kidneys, and intestine, while TSH is a peptide hormone secreted by the pituitary gland, which stimulates the thyroid gland to produce thyroxine and triiodothyronine in order to stimulate the metabolism of almost every tissue in the body.

Peptide hormones are hormones whose molecules are peptides in nature. These hormones have an effect on the endocrine system of animals, including humans. When a peptide hormone binds to a receptor on the surface of the cells, a second messenger appears in the cytoplasm. This triggers signal transduction that leads to cellular processes. PTH and TSH are two types of peptide hormones.

CONTENTS

1. Overview and Key Difference
2. What is PTH
3. What is TSH
4. Similarities – PTH and TSH
5. PTH vs TSH in Tabular Form
6. Summary – PTH vs TSH

What is PTH?

Parathyroid hormone (PTH) is a peptide hormone secreted by the parathyroid gland. It regulates serum calcium ion concentration through its effect on bone, kidney, and intestine. PTH normally influences bone remodelling, which is a process in which bone tissue is alternately resorbed and rebuilt over time. This hormone is secreted in response to low blood serum calcium (Ca²⁺) levels. PTH stimulates osteoclast activity within the bone matrix in order to release more ionic calcium into the blood, which elevates the low serum calcium level. Therefore, PTH is like a key that unlocks the bank vault to remove the calcium.

PTH is secreted typically by the chief cells of the parathyroid glands. This polypeptide contains 84 amino acids. It is a prohormone of molecular weight around 9500 Da. The action of PTH is opposed to the hormone calcitonin. There are two types of receptors for this hormone: parathyroid hormone 1 receptor and parathyroid hormone 2 receptor. Parathyroid hormone 1 receptors are present at high levels on the cells of bone and kidney, while parathyroid hormone 2 receptors are present at high levels on the cells of the central nervous system, pancreas, testes, and placenta.

What is TSH?

Thyroid-stimulating hormone (TSH) is a peptide hormone secreted by the pituitary gland. TSH stimulates the thyroid gland to produce thyroxine (T4) and triiodothyronine (T4) in order to stimulate the metabolism of almost every tissue in the body. TSH is a glycoprotein. It is produced by the thyrotrope cells in the anterior pituitary gland. TSH mainly regulates the endocrine function of the thyroid.

TSH hormone has two subunits: α subunit and β subunit. α subunit is thought to be the effector region responsible for the stimulation of adenylate cyclise. It has 92 amino acids. β subunit is unique to TSH, and it determines the receptor specificity of TSH. It has 118 amino acids. Furthermore, the TSH receptor is mainly found in thyroid follicular cells.

What are the Similarities Between PTH and TSH?

• PTH and TSH are two types of peptide hormones.
• Both hormones are made up of amino acids.
• They have specific receptors in the body.
• They perform very important endocrine functions in the body.

What is the Difference Between PTH and TSH?

PTH is a peptide hormone secreted by the parathyroid gland to regulate serum calcium ion concentration through its effect on bone, kidney, and intestine, while TSH is a peptide hormone secreted by the pituitary gland, which stimulates the thyroid gland to produce thyroxine (T4) and triiodothyronine (T4) in order to stimulate the metabolism of almost every tissue in the body. Thus, this is the key difference between PTH and TSH. Furthermore, PTH is produced by the chief cells of parathyroid glands, while TSH is produced by the thyrotrope cells in the anterior pituitary gland.

The below infographic presents the differences between PTH and TSH in tabular form for side by side comparison.

Summary – PTH vs TSH

Peptide hormones are hormones made up of amino acids. They are peptides in nature. PTH and TSH are two types of peptide hormones. PTH is a peptide hormone secreted by the parathyroid gland. It regulates serum calcium ion concentration through its effect on bone, kidney, and intestine. TSH is a peptide hormone secreted by the pituitary gland. It stimulates the thyroid gland to produce thyroxine (T4) and triiodothyronine (T4) in order to stimulate the metabolism of almost every tissue in the body. So, this summarizes the difference between PTH and TSH.

Reference:

1. “Parathyroid Hormone.” You and Your Hormones.
2. “Thyroid-Stimulating Hormone (TSH): TSH Levels Test.” WebMD.

Image Courtesy:

1. “Major interactions between vitamin D, parathyroid hormone (PTH), calcium and phosphorus around the body” By sportEX journals (CC BY-ND 2.0) via Flickr
2. “Figure 37 04 01” By CNX OpenStax – (CC BY 4.0) via Commons Wikimedia