Every second, your body is sending dozens of invisible messages that dictate when you're hungry, how your metabolism works, how you react to stress, and whether you sleep soundly or wake up tired. These messages are sent by hormones, chemicals that influence almost every process in your body.

Hormones function as an invisible coordination system that sends signals to organs, muscles, skin, and other tissues to keep your body functioning properly. When their levels rise or fall outside normal limits, your internal balance can be disrupted. But to understand how they affect your health, you first need to know what hormones are, how they work, and how they work.

What are hormones and how do they work in the body?

Hormones are chemicals produced by the endocrine glands. They act as the body's internal communication system and coordinate vital processes at every stage of life. They are released into the bloodstream by specialized groups of cells called glands, where they circulate throughout the body and transmit instructions to target cells.

Hormones are chemical messengers of the endocrine system.

Hormones are chemical messengers produced by the endocrine glands. These glands are specialized groups of cells that make up the endocrine system and release substances directly into the bloodstream.

Once in the blood, hormones travel to their target organs or tissues, where they bind to specific receptors and transmit precise information. Each hormone has a well-defined role and coordinates a specific organ or cell type. Insulin, for example, regulates blood sugar levels. Estrogen and progesterone regulate the menstrual cycle, pregnancy, and other important processes in the female body.

Together, all of these hormones efficiently coordinate internal functions and maintain homeostasis, or the body's internal balance. In other words, they play an important role in stabilizing blood sugar, blood pressure, body temperature, and many other vital parameters.

Hormones and the difference between the endocrine system and the nervous system

The endocrine system and the nervous system work together to coordinate the body's functions through different mechanisms.

The nervous system transmits information through electrical impulses and reacts almost instantly to stimuli, while the endocrine system releases hormones into the blood that act more slowly and regulate long-term processes, such as growth, development, metabolism, or the menstrual cycle.

The type of "messenger" used differs for the two systems. The endocrine system communicates through hormones carried in the blood to organs and tissues, while the nervous system uses neurotransmitters to transmit rapid signals between neurons.

How do hormones work and how do they influence target cells?

Hormones are secreted into the blood and transported to target organs or tissues, where they interact with specific cell receptors. Their effect on the body depends on the type of hormone and the mechanism by which it influences cell activity.

Hormones aid in secretion and transport through the blood

Endocrine glands secrete hormones directly into the bloodstream. Once in the bloodstream, they circulate throughout the body, but they only influence target organs and act only on cells that have specific receptors for them.

Depending on the type of hormone, the way it is transported through the blood also differs. For example, steroid hormones such as cortisol, estrogen, and progesterone, which are derived from cholesterol and are hydrophobic, cannot circulate freely through the watery plasma. Therefore, they are transported bound to plasma proteins in order to reach their target cells safely.

Hormones act through specific cell receptors

To exert their effects on target organs, hormones must bind to specific cell receptors. Receptors are located either on the cell membrane or in the nucleus. Once bound to the receptors, hormones transmit the message to the cells that triggers a specific action.

Hormones that cannot cross the cell membrane bind to receptors in the membrane and trigger intracellular biochemical reactions that lead to changes in the cell's activity. Those that can penetrate the cell, such as steroid hormones, bind to nuclear receptors and can activate or inhibit certain genes in the DNA.

Hormones work through the lock-and-key mechanism

Hormone action is based on a principle known as the lock-and-key mechanism. Just as a key can only open a specific lock, each hormone has a specific chemical structure that is compatible only with certain receptors.

Therefore, each hormone can only bind to cells that have compatible receptors. This explains why different hormones affect only certain tissues and organs even though they circulate throughout the body.

When binding occurs, hormones trigger a specific cellular response. This can be stimulating a function, inhibiting a process, changing the rate of cell division, or adjusting the production of other substances needed by the body.

Hormones are regulated by negative and positive feedback

The amount that the glands produce of each hormone is very precisely controlled. The human body is able to appreciate when it is necessary to secrete a smaller or larger amount of a particular hormone and to control the secretion through self-regulatory mechanisms. The main such mechanisms are negative feedback and positive feedback.

Negative feedback is more common and serves to maintain hormone levels within optimal ranges. If the level of a hormone increases above a certain limit, the body reduces secretion to prevent excess.

Positive feedback is rarer and involves a temporary increase in hormonal secretion until a certain physiological goal is reached, after which the mechanism stops.

Hormonal imbalances occur when these control mechanisms are impaired and can no longer prevent the insufficient or excessive secretion of certain hormones. Such situations can disrupt hormonal balance and compromise the normal functioning of the body.

Hormones and the endocrine system – the glands that produce hormones

Most hormones in the body are produced in specialized organs that make up the endocrine system. This system is made up of a collection of glands that produce and release hormones directly into the bloodstream.

Each gland has a well-defined role and secretes specific hormones to regulate essential functions such as growth, metabolism, blood sugar, and stress response:

• Hypothalamus: produces corticotropin-releasing hormone (CRH), gonadotropin-releasing hormone, dopamine, oxytocin, and somatostatin, which control the activity of the pituitary gland and maintain the body's internal balance.
• Pituitary gland: also called the master gland, it secretes hormones involved in development, lactation and reproductive function such as adrenocorticotropin (ACTH), follicle-stimulating hormone (FSH), human growth hormone (hGH), luteinizing hormone (LH), prolactin, thyroid-stimulating hormone (TSH), antidiuretic hormone (ADH) and oxytocin.
• Thyroid: produces thyroxine (T4), triiodothyronine (T3), Reverse T3, and calcitonin, which control metabolism, body temperature, and energy levels.
• Adrenal glands: release hormones involved in the stress response, but also hormones that contribute to the regulation of blood pressure and electrolyte balance (adrenaline, noradrenaline, cortisol, aldosterone, DHEA and androgen hormones).
• Endocrine pancreas: Endocrine cells in the pancreas produce insulin and glucagon, which keep blood sugar levels within normal limits.
• Ovaries and testicles: release sex hormones (estrogen, progesterone, and testosterone).
• 

Not all organs and tissues that release hormones are part of the endocrine system. For example, although adipose (fat) tissue, kidneys, liver, and placenta release hormones, they are not part of the endocrine system.

How do hormones influence menstruation and the menstrual cycle?

The menstrual cycle is the result of a hormonal balance coordinated by the interaction between the brain and the ovaries. Monthly fluctuations in hormonal levels determine ovulation, the preparation of the endometrium and the onset of menstruation, and any change in this balance can influence the regularity and characteristics of the cycle.

Hormones control the monthly menstrual cycle

The menstrual cycle is mainly regulated by the female hormones estrogen and progesterone . They determine the development of the uterine lining and prepare the body each month to support a possible pregnancy.

The pituitary gland secretes FSH (follicle-stimulating hormone) and LH (luteinizing hormone), which coordinate the process of ovarian follicle maturation and ovulation . In the absence of pregnancy, the uterine lining is shed through menstruation and the cycle resumes.

The balance between these hormones is the basis of a regular menstrual cycle, with predictable intervals between periods. On your period days, use hypoallergenic menstrual products with 100% organic cotton to feel as comfortable as possible.

Hormones and menstrual disorders

Hormonal imbalances can lead to menstrual irregularities. Irregular menstruation, absence of ovulation, and abnormal bleeding may indicate an ovarian, pituitary, or thyroid imbalance, and are associated with conditions such as polycystic ovary syndrome (PCOS) or thyroid problems.

These imbalances can manifest in women through severe menstrual pain, menorrhagia (heavy bleeding) or very long or very short cycles, symptoms that should be investigated medically.

What types of hormones are there and how do hormones act?

There are many types of hormones that, in addition to being grouped according to the gland that produces them, can be classified according to their chemical structure and the way they act on target cells. They can be water-soluble or fat-soluble depending on their composition, which further determines the speed of action, the duration of the effect and the mechanism by which they influence the functions of the body.

Peptide hormones and their metabolic role

Peptide hormones are made up of chains of amino acids and are water-soluble, meaning they dissolve easily in the blood. For this reason, they circulate freely in the plasma, without the need for carrier proteins. They cannot cross the cell membrane, so they bind to receptors located on the cell surface and trigger rapid reactions inside, which is why their effects occur quickly.

The role of peptide hormones is to regulate metabolism and growth. Growth hormone, for example, is involved in tissue development and body mass. Insulin, another peptide hormone, plays a role in regulating blood sugar levels.

Steroid hormones derived from cholesterol

Steroid hormones are derived from cholesterol and are liposoluble, meaning they dissolve in fat. This allows them to easily cross cell membranes. Unlike peptide hormones, they need to be bound to carrier proteins to circulate in the blood.

Once inside the cell, steroid hormones bind to intracellular receptors and can directly influence gene expression, producing longer-lasting effects on the body. This category includes cortisol, which is involved in the stress response, testosterone, estrogen, and progesterone.

Hormones derived from amino acids

Amino acid-derived hormones are usually derived from the modification of amino acids such as tyrosine or tryptophan. This category includes adrenaline, thyroxine, and melatonin.

Depending on the type, hormones derived from amino acids can have rapid effects similar to peptide hormones, or prolonged effects on complex metabolic processes and physiological functions.

What functions do hormones have in the body?

Hormones coordinate numerous processes and functions that allow the body to adapt to the internal and external environment and function optimally:

• Regulates metabolism
• Influences growth and development
• Controls reproductive function
• Manages stress response
• Regulates sleep and circadian rhythm
• Influences appetite and body weight

For this reason, even a small change in hormonal levels can trigger major changes in the body and cause various conditions that require medical treatment.

What are hormonal disorders and how do hormonal imbalances occur?

Hormonal imbalances occur when the levels of one or more hormones rise or fall outside normal limits, or when target cells do not respond appropriately to the hormonal signal. These imbalances can affect the functioning of multiple systems in the body and manifest differently depending on the hormones involved.

Hormonal disorders – common causes

Each type of hormonal imbalance and its associated conditions can have different underlying causes. The main situations that lead to imbalances in hormone levels include:

• Endocrine diseases or lesions in an endocrine gland
• Autoimmune disorders affecting the endocrine glands
• Chronic stress, which causes elevated cortisol levels
• Unbalanced diet, which can influence hormonal balance
• Hereditary genetic diseases, which can affect the structure or function of an endocrine gland

Hormonal disorders – common symptoms

Symptoms of hormonal imbalances vary depending on the hormones involved, but chronic fatigue is one of the most common signs. Hormonal imbalances can also cause weight fluctuations due to either changes in appetite or changes in how the body uses energy.

In women, symptoms of hormonal imbalance can include menstrual irregularities, severe menstrual pain, or changes in flow. In men, symptoms of hormonal imbalance such as decreased testosterone levels can lead to decreased libido, mood swings, and decreased muscle mass.

Hormonal disorders and endocrine diseases

Hormonal disorders are frequently associated with various endocrine diseases.

Diabetes, for example, occurs as a result of insulin dysregulation, a hormone responsible for regulating blood sugar. Hypothyroidism and hyperthyroidism are thyroid gland disorders that attack metabolism and energy levels.

Prolonged exposure of the body to excessive levels of cortisol can cause Cushing's syndrome, a severe endocrine condition that can lead to weight gain, hypertension, and skin changes.

In women, polycystic ovary syndrome (PCOS) affects female hormones and can influence ovulation, fertility, and menstrual cycle regularity.

How are hormones tested and when are hormone tests recommended?

There are several types of tests that allow the measurement of hormonal levels. They are recommended based on symptoms and clinical suspicions, and their purpose is to help identify imbalances and establish a correct diagnosis.

Blood tests for hormones

Hormonal blood tests allow the measurement of the concentration of certain hormones in serum or plasma and provide information about the functioning of the endocrine glands. These most often include TSH to assess thyroid function, cortisol, estrogen or testosterone, and their role is to help diagnose hormonal imbalances and monitor specific treatments.

Salivary and urinary hormone test

The saliva test is frequently used to assess cortisol levels, especially to track how they fluctuate throughout the day and to understand the natural rhythm of secretion.

Urine tests can analyze hormone metabolites, which are substances that are produced when hormones are processed in the body. These tests are sometimes used for a more detailed assessment of endocrine function.

When are hormone tests recommended?

Your doctor may recommend a set of hormone tests if you are experiencing persistent symptoms of hormonal imbalance, such as chronic fatigue or menstrual disorders. Hormone tests are also indicated for both women and men to evaluate reproductive function in case of fertility problems.

Other common situations in which hormone tests are recommended to confirm the diagnosis include suspected hypothyroidism, hyperthyroidism, and diabetes.

How do you maintain hormonal balance and regulate hormones naturally?

Maintaining hormonal balance involves adopting habits that support the optimal functioning of the endocrine system every day. The main measures you can take are to:

• Follow a balanced diet, rich in nutritious foods.
• You practice physical activities regularly.
• You give yourself time for rest and stress management techniques.

Frequently asked questions about hormones

Hormones influence almost every process in the body, which is why it can be a real challenge to understand what their role is, how they work, and why their levels can affect your mood and health so much. To help you understand better, below we have prepared answers to the most frequently asked questions about the functioning of the endocrine system.

What are hormones in short?

Hormones are chemical messengers produced by endocrine glands and released into the bloodstream to transmit information between different organs and tissues. They regulate essential body functions such as metabolism, growth, reproduction, sleep, and stress response.

What is the most important hormone?

There is no single hormone that is considered “the most important.” Each hormone has a specific role and contributes to maintaining internal balance. Hormones act interdependently within the endocrine system, and optimal functioning of the body depends on the balance between them, not on one alone.

How do you know if you have hormonal imbalances?

Symptoms of hormonal imbalances can include persistent fatigue, weight fluctuations, menstrual irregularities, and unexplained mood swings. To confirm a hormonal imbalance, your doctor may recommend a set of hormone tests depending on your symptoms.

Can hormones be regulated naturally?

The body naturally has a self-regulating system that maintains hormone levels within optimal ranges. This system can be supported through lifestyle, with a nutritious diet and regular physical activity that help maintain natural hormonal balance. However, if imbalances occur, medical treatment is most often necessary.

What is the connection between hormones and menstruation?

The female hormones estrogen and progesterone control the menstrual cycle and how the body prepares each month for a possible pregnancy. Thus, a hormonal imbalance can lead to irregular periods, lack of ovulation, or changes in menstrual flow.

What hormone tests are the most common?

Among the most common hormonal tests are:

• Thyroid hormone tests that allow the evaluation of thyroid function.
• Hormonal tests for cortisol, in the context of constant stress or suspicion of adrenal gland disorders.
• Estrogen and testosterone tests to evaluate reproductive function.

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