Introduction

What is the endocrine system?

The tissues (primarily glands) that produce and release hormones make up your endocrine system. By sending messages to your organs, skin, muscles and other tissues via your blood, hormones are chemicals that help your body coordinate various processes. Your body receives these signals to determine the next move. Your health and existence depend on hormones. Endocrine system disorders include several conditions, most of which are brought on by hormone imbalances or issues that directly impact the tissue. 

What is the function of the endocrine system?

The endocrine system regularly checks your blood levels and releases hormones into the bloodstream. Hormones use lock-in mechanisms to communicate with the cells they are meant to influence. Multiple aspects of your life, such as growth, development, metabolism, sexual function, and reproduction, are affected by more than 50 hormones. Your health is impacted by hormone levels that are either too high or too low.

What is the thyroid?

The thyroid is a small, butterfly-shaped gland located at the front of your neck under the skin, as illustrated in the figure below. It regulates your metabolic rate, which is how your body turns the food you eat into energy. Your entire body may be affected when your thyroid isn’t functioning properly. Triiodothyronine (T3) and thyroxine (T4), the two main hormones it synthesises, are both necessary for metabolic control.

Your body uses a complex system to control the quantity of these hormones. Thyrotropin-releasing hormone (TRH), triggered by the hypothalamus, forces your pituitary gland to release thyroid-stimulating hormone (TSH). This, in turn, stimulates your thyroid follicular cells to excrete T4 and T3 if there is sufficient iodine in your body.¹

Hypothyroidism and hyperthyroidism, two serious conditions that can arise from disruptions in thyroid hormone production or regulation, both contribute to systemic imbalance and widespread hormonal dysfunction.¹ For early diagnosis and successful treatment, it is crucial to comprehend these conditions, their causes, and their effects.

Hypothyroidism

Definition and causes

Hypothyroidism (underactive thyroid disease) happens when your thyroid gland does not produce or release adequate hormones into your bloodstream, resulting in a slower metabolism. You may unintentionally gain weight as a result and may experience constant fatigue. Though it can affect anyone, women over 60 are more likely to have hypothyroidism, especially after menopause.²

Hypothyroidism most often results from Hashimoto’s disease. It’s an autoimmune disease, so it happens when your immune system attacks your thyroid, damaging its ability to produce hormones.³

Other causes include: 

• Medications such as amiodarone, thalidomide, and lithium
• Conditions that exist from birth, such as having a thyroid gland that is malfunctioning or not functioning properly
• A deficiency in iodine, which occurs when the body does not contain enough of it
• Conditions involving the pituitary gland, such as benign tumours
• Thyroiditis: An inflammation of the thyroid that may occur following pregnancy or a viral illness⁴

Symptoms

Hypothyroidism symptoms usually develop slowly over time. In some cases, it can take years. Some possible symptoms are demonstrated in the figure below. However, in severe cases, untreated hypothyroidism can lead to myxoedema coma, a life-threatening condition involving altered mental status, hypothermia, and multisystem failure.⁵

Diagnosis

A medical professional will gently press around your thyroid to check for swelling during a physical examination. To make an accurate diagnosis of hypothyroidism, medical professionals typically perform thyroid tests.

Primary hypothyroidism is confirmed by elevated TSH levels and low free T4 levels. In secondary hypothyroidism, TSH and T4 levels are slightly lower.⁶ Since autoimmune thyroiditis usually results in elevated thyroid peroxidase antibodies (TPOAb), further research may be necessary. You might also require other imaging tests such as ultrasound, CT scan, or nuclear medicine imaging.

Treatment

Hormone replacement therapy is most often used to treat hypothyroidism. Levothyroxine is a drug that substitutes the hormones your thyroid is unable to produce on its own. Most people take it without food in the morning. Levothyroxine can reduce symptoms and balance hormone levels if taken daily. 

The ideal dosage will require trial and error, and your doctor might perform a few routine blood tests until your TSH levels are even.⁷ Although you can live a healthy life with careful management and regular check-ups with your doctor, you might require lifelong medication.

Hyperthyroidism

Definition and causes

High thyroid hormone production and release are symptoms of hyperthyroidism, also known as an overactive thyroid. Your metabolism is accelerated by hyperthyroidism, which may have an impact on several of your health issues. It’s possible that you don’t feel like yourself or even that your body is out of control. If you experience symptoms of hyperthyroidism, it’s critical to seek medical attention so you can resume your normal self-care. Hyperthyroidism affects more women than men and can happen at any age, despite being relatively uncommon, like hypothyroidism.⁸

Hyperthyroidism can be caused by the following illnesses and circumstances:⁹

• Graves’ disease: An autoimmune disorder that causes hyperactivity in the thyroid. It is the most common cause of hyperthyroidism
• Thyroid nodules: Growths or lumps that develop in the thyroid gland. At times, they may generate too much thyroid hormone
• Thyroiditis: The inflammation of your thyroid gland. It may momentarily result in hyperthyroidism
• Excessive iodine consumption: Your thyroid may produce more thyroid hormone if you consume an excessive amount of iodine through food or medication

Symptoms

Hyperthyroidism has a wide range of symptoms that can affect your entire body. You might have a number of these symptoms at once, or you might only have some of them. Furthermore, if left untreated, Graves’ disease-induced hyperthyroidism can worsen over time and result in complications like pretibial myxoedema and ophthalmopathy, or bulging of the eyes.¹⁰

Diagnosis

Accurate diagnosis of hyperthyroidism includes several procedures:¹¹

• Physical exam: Your doctor will first perform a physical examination to look for symptoms of hyperthyroidism, such as an enlarged thyroid, a fast heartbeat, and warm, wet skin
• Thyroid blood tests: To measure your thyroid hormone levels. Thyroid-stimulating hormone (TSH) is frequently (though not always) lower than normal in people with hyperthyroidism, while thyroid hormone levels T3 and T4 are higher than normal
• Imaging: A thyroid ultrasound and a radioactive iodine uptake test are the options

Treatment

There are numerous ways to treat hyperthyroidism, and your doctor will assist you in deciding the best course of action appropriate to your situation. Typical choices include:

• Antithyroid drugs: Propylthiouracil (PTU) and methimazole (Tapazole®) prevent your thyroid from producing hormones. You might feel better after a few weeks
• Radioactive iodine (RAI) therapy: It involves the administration of a capsule or liquid dose of radioactive iodine. It targets your thyroid cells
• Surgery: A thyroidectomy is when a surgeon removes all or part of your thyroid gland
• Beta-blockers: These drugs can help control the symptoms of hyperthyroidism, such as hesitancy, anxiety, and a fast heartbeat. However, they don’t alter your blood’s hormone levels

All these treatment options come with certain risks and benefits. So, do not hesitate to have a detailed discussion with your provider and ask questions before deciding.

Hormonal imbalance

A hormonal imbalance occurs when one or more of them are either too high or too low. A broad variety of diseases linked to hormones can be referred to by this general term. The duration of hormonal imbalances can vary from brief to prolonged. Furthermore, while some hormonal imbalances may not affect your health directly, they may negatively impact your quality of life. Some hormonal imbalances must be addressed to preserve your physical health. Your metabolism may be impacted by common hormonal imbalances. In females, progesterone and oestrogen hormone levels can be disrupted. They might also have too much androgen and testosterone. For males, it can cause erectile dysfunction, loss of body hair, lower libido, and even infertility. 

Moreover, hypothyroidism is associated with menstrual irregularities, infertility, and elevated prolactin levels, which can suppress ovulation. Hyperthyroidism may also cause amenorrhoea or oligomenorrhoea due to altered oestrogen metabolism and gonadotropin secretion.¹²

Mental health is another major area impacted by thyroid dysfunction. Hypothyroidism is strongly linked with depression, slowed cognition, and memory problems, while hyperthyroidism can lead to anxiety, restlessness, and even psychosis in severe cases.¹³

Cardiovascular risks are significantly altered in both conditions. Hypothyroidism contributes to hyperlipidaemia, atherosclerosis, and bradycardia, increasing the risk of coronary artery disease. Conversely, hyperthyroidism elevates heart rate, induces atrial fibrillation, and increases the risk of heart failure, especially in older adults.¹⁴

Summary

The endocrine system comprises glands that release hormones to regulate many vital functions in your body, such as metabolism, growth, mood, and reproduction. One important gland is the thyroid, which produces hormones that control how your body uses energy. A disorder in your thyroid can cause either hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). Hypothyroidism can make you feel tired, gain weight, and feel low, while hyperthyroidism may lead to anxiety, weight loss, and a fast heartbeat. 

These conditions may also impact your heart function, fertility, and mental health. Diagnosis usually involves blood tests and imaging, and treatment may include hormone replacement, antithyroid medicines, or surgery. With the right treatment and regular monitoring, these conditions can be well managed, helping you feel better and avoid long-term complications.