Difference Between Thyroid And Parathyroid: Symptoms & Causes

Introduction — Why Thyroid vs Parathyroid Is Important

The thyroid and parathyroid glands are major endocrine organs concerned with several key functions of the body. Although both are localised in the neck and endocrine glands, they exert different physiological functions. The thyroid affects almost all metabolic processes, whereas the parathyroid glands have roles in the maintenance of calcium homeostasis—an excellent example of the specificity in endocrine regulation.

Overview of Thyroid and Parathyroid Glands

The overview of thyroid and parathyroid glands is given below:

Thyroid Gland

• Controls metabolic rate

• Regulates heart rate and warms up the body temperature

• Secretes thyroid hormones

Parathyroid Gland

• Regulate blood calcium level

• Maintains bone metabolism

• Secretes parathyroid hormone

Anatomy and Location

Knowing the anatomy and position of the thyroid and parathyroid glands, one can explain their functions and associated diseases.

Thyroid Gland Anatomy

• Butterfly-shaped gland with two lobes connected by an isthmus.

• 4-6 cm in length, 1-2 cm in width.

• Located below the Adam's apple and in front of the trachea.

Parathyroid Gland Anatomy

• Four small, oval-shaped glands

• 3-4 mm (grain of rice)

• Location on the posterior surface of the thyroid gland, two on each side.

Functions of Thyroid vs Parathyroid

The functions of the thyroid and parathyroid glands are different and crucial to other homeostatic functions of the body.

Thyroid Gland Functions

• Production of thyroid hormones T3 and T4

• Regulates metabolism, heart rate, body temperature

Parathyroid Gland Functions

• Production of parathyroid hormone (PTH)

• Regulation of calcium levels in the blood

• Bone remodelling.

Hormonal Control and Feedback Mechanisms

Analysing the hormonal control and feedback mechanisms for these glands gives an idea of how they participate in homeostasis.

Thyroid Gland Control

• Hypothalamus releases TRH, which stimulates the pituitary to release TSH.

• This in turn stimulates the thyroid to produce T3 and T4.

• Negative feedback inhibits TRH and TSH.

Parathyroid Gland Control

• Controlled by blood calcium amount

• Decreased calcium levels induce PTH release.

• PTH increases blood calcium by acting on bones, kidneys and intestine.

Common Disorders

Different pathologies can simultaneously alter thyroid and parathyroid glands, impairing their normal functioning.

Thyroid Disorders

• Hyperthyroidism: Overproduction of thyroid hormones

• Hypothyroidism: Underproduction of thyroid hormones

• Thyroid nodules and cancer: Abnormal growths or malignancies in the thyroid.

• Treated by medications, radioactive iodine therapy and surgery.

Parathyroid Disorders

• Hyperparathyroidism: Excessive PTH production.

• Hypoparathyroidism: Inadequate PTH production.

• Parathyroid tumours: Abnormal growths in the parathyroid glands.

• Treated by surgery and calcium or vitamin D supplements .

Thyroid vs Parathyroid — Comparison Table

The difference between thyroid and parathyroid is discussed in the table below:

Thyroid vs Parathyroid Gland NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Functions of thyroid and parathyroid gland

• Thyroid vs Parathyroid gland

Practice Questions for NEET

Q1. The blood calcium level is lowered by the deficiency of

1. Thyroxine

2. Calcitonin

3. Parathormone

4. Both 1 and 2

Correct answer: 3) Parathormone

Explanation:

The parathyroid glands secrete a peptide hormone called parathyroid hormone (PTH), which plays a crucial role in regulating calcium levels in the blood. The secretion of PTH is primarily controlled by the circulating levels of calcium ions. When blood calcium levels drop, the parathyroid glands increase the release of PTH to stimulate the release of calcium from bones, increase calcium reabsorption by the kidneys, and promote the activation of vitamin D, which enhances calcium absorption from the intestines. Conversely, when calcium levels rise, the secretion of PTH is reduced, maintaining a balanced calcium concentration in the body.

Hence the correct answer is option 3) Parathormone.

Q2. Tetany is caused by

1. Hyperparathyroidism

2. Hypoparathyroidism

3. Hypothyroidism

4. Hyperthyroidism

Correct answer: 2) Hypoparathyroidism

Explanation:

The clinical complications associated with hypoparathyroidism can result in a disorder termed parathyroid tetany or hypocalcemic tetany, characterized by involuntary muscle contractions that can be distressing and potentially dangerous. Proper diagnosis and management of this condition are essential to restore calcium balance and reduce symptoms.

Hence, the correct answer is option 2) Hypoparathyroidism.

Q3. Which of the following hormones can play a significant role in osteoporosis?

1. Estrogen and Parathyroid hormone

2. Progesterone and Aldosterone

3. Aldosterone and Prolactin

4. Parathyroid hormone and Prolactin

Correct answer: 1) Estrogen and Parathyroid hormone

Explanation:

Estrogen: By preventing bone resorption, or breakdown, this hormone aids in maintaining bone density. Osteoporosis is a disorder in which bones become weak and can be exacerbated by a reduction in estrogen levels, such as occurs after menopause.

Parathyroid hormone (PTH): PTH affects bone metabolism and controls blood calcium levels. Increased bone resorption brought on by high PTH levels can erode bones even more and exacerbate osteoporosis. PTH promotes bone breakdown to release calcium into the bloodstream when blood calcium levels are low.

Hence, the correct answer is option 1)Estrogen and Parathyroid hormone.

Also Read:

• MCQs on Parathyroid Gland

• Mechanism of Hormone Action

• Adrenal Gland

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