Are there any diseases that affect the endocrine system?

There are several diseases that affect the endocrine system, and the most common ones are:

• Diabetes
• Hyperthyroidism
• Hypothyroidism
• Addison’s Disease
• Cushing’s Disease
• Acromegaly
• Dwarfism
• Gigantism
• Hypogonadism
• Polycystic Ovary Syndrome (PCOS)

1. What Is Diabetes?

Diabetes is a chronic disease characterized by the presence of a high level of glucose in the blood due to the lack of insulin production by the pancreas or the reduced capacity of tissues to use insulin [1].

Diabetes is the 9^th leading cause of death with an estimated 1.5 million deaths just in 2019 [2].

According to the 2020 statistics, it was estimated that 34.2 million Americans have diabetes and 88 million Americans have prediabetes [1].

1.1. What Does Insulin Do in the Body?

Insulin is a hormone produced by the beta cells of the pancreatic islets (islets of Langerhans) which role is to promote the absorption of glucose from the blood into liver, fat, and muscle cells where it is stored as glycogen or fat.

1.2. What Are the Types of Diabetes?

There are 2 types of diabetes, type 1 diabetes, and type 2 diabetes; however, there is another type of diabetes that occurs during pregnancy and is known as gestational diabetes.

• What Is Type 1 Diabetes?

Type I diabetes is an autoimmune disease characterized by reduced or lack of insulin production by the pancreatic islets due to their destruction by the body’s own immune system.

The causes of typ1 diabetes are unknown but may involve genetics and environmental factors.

• What Is Type 2 Diabetes?

Type II diabetes is a chronic disease associated with a decreased production of insulin by the pancreatic islets or the absence of response of the body’s cells to insulin, also known as insulin resistance.

Type II diabetes is caused by genetics and lifestyle factors such as obesity, being overweight, lack of physical activity, and stress.

• What Is Gestational Diabetes?

Gestational diabetes is characterized by increased glucose levels in the blood during pregnancy and which usually disappears after giving birth.

1.3. What Are the Symptoms of Diabetes?

Because insulin is lacking or insufficiently available, or the cells of the body do not respond to it, there is an increased accumulation of glucose in the blood and its reduced absorption by the body’s cells.

The lack of glucose absorption by the body’s cells results in symptoms such as fatigue, blurred vision, increased hunger, slow wound healing, and weight loss.

The accumulation of glucose in the blood results in symptoms such as frequent urination (to eliminate the excess), increased thirst, and complications including diabetic neuropathy, kidney failure, and cardiovascular diseases.

2. What Is Hyperthyroidism?

Hyperthyroidism is a disorder characterized by excessive production of the thyroid hormones by the thyroid gland [3].

2.1. What Are Thyroid Hormones?

The thyroid hormones are thyroxine (T4) and triiodothyronine (T3) involved in the regulation of carbohydrate, fat, and protein metabolisms, and growth.

2.2. What Causes Hyperthyroidism?

Hyperthyroidism is caused by the following disorders:

• Graves’ Disease
• Toxic Adenoma
• Silent or Painless Thyroiditis
• Toxic Multinodular Goiter

2.2.1. What Is Grave’s Disease?

Graves’ disease is an autoimmune disease characterized by the body’s production of autoantibodies against the receptor of the thyroid-stimulating hormone (TSH) found on the surface of the thyroid cells.

The binding of the autoantibodies to the TSH receptor results in excessive production of the thyroid hormones thyroxine (T4) and triiodothyronine (T3).

2.2.2. What Is Toxic Adenoma?

A toxic adenoma is a benign tumor of the thyroid that results in excessive production of thyroid hormones.

2.2.3. What Is Silent or Painless Thyroiditis?

Silent or painless thyroiditis is an inflammation of the thyroid resulting in increased production of thyroid hormones.

2.2.4. Toxic Multinodular Goiter

Toxic multinodular goiter is characterized by the formation of nodules within the thyroid responsible for the increased production of thyroid hormones.

2.2. What Are the Symptoms of Hyperthyroidism?

Hyperthyroidism causes thyrotoxicosis characterized by the following symptoms:

• Nervousness and irritability
• Increased heartbeat
• Hand tremors (uncontrollable shaking)
• Anxiety
• Muscles weakness
• Increased perspiration or trouble tolerating heat
• Repeated bowel movements
• Sleep difficulty
• Enlargement in the neck, also known as goiter

3. What Is Hypothyroidism?

Hypothyroidism is characterized by a reduced production of thyroid hormones by the thyroid [4].

3.1. What Causes Hypothyroidism?

The causes of hypothyroidism can be divided into 3 categories: Primary hypothyroidism, central hypothyroidism, and congenital hypothyroidism.

• What Is Primary Hypothyroidism?

Primary Hypothyroidism is caused by a deficiency in iodine, necessary for the synthesis of thyroid hormones, and thyroiditis.

• What Is Central Hypothyroidism?

Central Hypothyroidism is caused by insufficient stimulation of the thyroid by the thyroid-stimulating hormone (TSH) due to brain tumors (e.g., tumor of the pituitary gland), hematological malignancies, pituitary gland surgery, or post-surgery radiation.

• What Is Congenital Hypothyroidism?

Congenital Hypothyroidism is due to a defect in the development of the thyroid.

3.2. What Are the Symptoms of Hypothyroidism?

The symptoms of hypothyroidism include:

• Fatigue
• Weight gain
• Feeling cold
• Constipation
• Hoarse voice
• Poor appetite
• Shortness of breath
• Impaired memory and concentration
• Depression
• Enlargement in the neck, also known as goiter

4. What is Addison’s Disease?

Addison’s Disease is characterized by insufficient production of steroid hormones (cortisol and aldosterone) by the adrenal gland causing adrenal deficiency [5].

4.1. What Causes Addison’s Disease?

Adrenal deficiency is caused by damage to the adrenal gland (adrenal cortex), developmental defects, or the incapacity of the adrenal gland to produce steroid hormones.

4.2. What Are the Symptoms of Addison’s Disease?

Addison’s Disease manifests with the following symptoms:

• Hyperpigmentation of the skin
• Vitiligo
• Nausea and vomiting
• Weight loss
• Abdominal pain
• Extreme fatigue
• Muscle or joint pain
• Anxiety
• Depression
• Irritability
• Poor concentration
• Body hair loss or sexual dysfunction in women
• Low blood pressure

A severe state of Addison’s disease known as adrenal crisis or Addisonian crisis manifests with severe symptoms such as hypoglycemia, hypotension, legs, and lower back pain, nausea and vomiting, abdominal pain, confusion and delirium, and severe weakness.

5. What Is Cushing’s Disease?

Cushing’s Disease is characterized by increased production of cortisol by the adrenal glands [6].

5.1. What Causes Cushing’s Disease?

The increased production of cortisol by the adrenal glands is due to the overproduction of the hormone adrenocorticotropic hormone (ACTH) by the pituitary gland due to the presence of a tumor.

This increased production of ACTH increases the stimulation of the adrenal glands to secrete excess cortisol.

Cushing’s Disease can also be caused by tumors in the adrenal glands resulting in the excess production of cortisol.

5.2. What Are the Symptoms of Cushing’s Disease?

The most common symptoms of Cushing’s disease are:

• Weight gain
• Round face
• Hypertension
• Bone weakness
• Lack of strength in the upper arms and thighs
• Fatigue
• Purple stretch marks
• Irregular menstruation
• Excessive bruising
• Irritability
• Short-term memory deficit
• Lack of concentration
• Facial hair growth (Women)
• Depression

6. What Is Acromegaly?

Acromegaly is a condition characterized by the excess production of the growth hormone (GH) by the pituitary gland [7].

6.1. What Causes Acromegaly?

Acromegaly is mainly caused by a tumor in the pituitary gland known as pituitary adenoma resulting in increased secretion of growth hormone (GH).

6.2. What Are the Symptoms of Acromegaly?

Growth hormone (GH) controls the growth of the body, and its excess may result in the following symptoms:

• Enlargement of the forehead, nose, jaw, and tongue
• Deep voice
• Thick skin
• Increased sweating and skin odor
• Swollen hands and feet
• Headaches
• Join pain
• Vision problem

7. What Is Dwarfism?

Dwarfism is a condition characterized by short stature of 4’10” or shorter [8].

7.1. What Causes Dwarfism?

They are many causes of dwarfism; however, the most common cause is achondroplasia which is a disorder that affects bone growth due to a deficit in the production of bone from cartilage [9].

8. What Is Gigantism?

Gigantism is a condition characterized by the excess production of the growth hormone (GH) during childhood resulting in excessive growth in height, muscles, and organs, compared to other children at the same age. 

8.1. What Causes Gigantism?

The increase in the production of growth hormone (GH) during childhood is mainly due to benign tumors in the pituitary gland.

9. What Is Hypogonadism?

Hypogonadism is a disorder characterized by a reduced function of the ovaries or testes resulting in decreased production of sex hormones such as estrogen for females and testosterone for males [10][11].

9.1. What Causes Hypogonadism?

Hypogonadism can be due to primary or secondary causes:

9.1.1. What Is Primary Hypogonadism?

Primary hypogonadism is due to the incapacity of the gonads (ovaries or testes) to produce sex hormones even after stimulation by the pituitary gland.

Primary hypogonadism can be associated with the following causes:

• Genetic diseases such as Noonan syndrome, Turner syndrome or Klinefelter syndrome
• Undescended testicles
• Mumps orchitis
• Hemochromatosis
• Normal aging
• Cancer treatment
• Injury to testicles

9.1.2. What Is Secondary Hypogonadism?

Secondary hypogonadism is due to alterations in the hypothalamus or pituitary glands resulting in absence of stimulation of the gonads (ovaries or testes) to produce sex hormones.

Secondary hypogonadism can be associated with the following causes:

• Kallmann syndrome (abnormal development of the hypothalamus)
• Pituitary disorders
• Inflammatory diseases
• Obesity
• Stress-induced hypogonadism
• HIV/AIDS
• Medications (e.g., opiate based medications or some hormones)

9.2. What Are the Symptoms of Hypogonadism?

In females, hypogonadism manifests with the absence of menstruation which may affect their growth, breast development, and libido.

In males, hypogonadism manifests with abnormal enlargement of the breasts (gynecomastia), impairment of the development of hair and muscles, reduced height, and sexual difficulties (e.g., erectile dysfunction).

10. What Is Polycystic Ovary Syndrome (PCOS)?

PCOS is a hormonal disorder characterized by the presence of cysts on the ovaries which affects their normal function resulting in infrequent or prolonged menstrual periods or excess male hormone levels [12].

10.1. What Causes Polycystic Ovary Syndrome (PCOS)?

The causes are not well known and may involve genetics and environmental factors (e.g., obesity, epigenetic factors, or endocrine disruptors such as bisphenol).

9.2. What Are the Symptoms of Polycystic Ovary Syndrome (PCOS)?

PCOS can manifest with the following symptoms:

• Irregular periods
• Hair growth on the face and body
• Acne
• Pelvic pain

Conclusion

Due to the importance of the endocrine system for body function, any anomalies in the control, regulation, production, secretion, and activity of hormones can lead to conditions or disorders that affect development, growth, and reproduction.