Image of neurons
Patient Resources

Brain Hormones

January 24, 2022

The pituitary gland and the hypothalamus—are located in or near the brain. The hypothalamus and the pituitary gland are like orchestra conductors. Their job is to tell other endocrine glands throughout the body to make the hormones that affect and protect every aspect of your health. Found deep inside the brain, the hypothalamus produces releasing and inhibiting hormones and controls the “master gland”— the pituitary. Together, the hypothalamus and pituitary tell the other endocrine glands in your body to make the hormones that affect and protect every aspect of your health.

Pineal glands is important for the sleep cycle regulation of female reproductive hormone associated with fertility and menstrual cycle. Researchers are still learning about the potential functions of the pineal gland and the hormone melatonin. Other hormones produced in the brain are:

  • Antidiuretic Hormone (ADH) - also called vasopressin, which regulate sodium levels and water balance. Lack of ADH causes increased urination and thirst, a condition that is called diabetes insipidus.
  • Thyrotropin-releasing hormone (TSH) is produced in the hypothalamus and stimulates the release stimulates the thyroid gland to produce thyroid hormones. Too much TSH is rare and will cause hyperthyroidism (too much thyroid hormone). Lack of TSH results in hypothyroidism (not enough thyroid hormone). 

Hypothalamus Hormones

Kisspeptin, made in the hypothalamus, is an important hormone that starts the release of several other hormones. Also called metastin, this interesting hormone is connected to puberty and may also help stop the spread of cancer.

What Does Kisspeptin Do?

Kisspeptin enters into receptor sites in the pituitary gland, starting a reaction that causes the gland to release neurotransmitters. Those neurotransmitters then signal the release of luteinizing hormone and follicle stimulating hormone. These hormones have a role to play in the production of testosterone and oestradiol. Without kisspeptin, this entire chain reaction would be damaged.

Kisspeptin has a secondary function that is not related to hormones. Its original name, metastin, points to its ability to prevent the spread of cancer in the body.Kisspeptin is released in conjunction with two other hormones: dynorphin and neurokinin B. These two hormones are not understood well, but early research indicates they may have a role in causing the release of kisspeptin.

Potential Problems with Kisspeptin Levels

Having high levels of kisspeptin is not related to any conditions or symptoms, although preliminary research indicates that high kisspeptin levels in childhood can lead to early puberty, but this has not yet been proven. Research has also found that women have high levels of kisspeptin in their blood streams during pregnancy, but why this occurs is not yet understood.

Improper kisspeptin function or low kisspeptin levels, however, can cause problems. Specifically, inadequate function of this hormone can cause infertility by preventing menstruation in women. Sometimes, just one injection of kisspeptin can trigger ovulation, which can allow for artificial insemination and in vitro fertilization using the woman's eggs.

In adolescents, low kisspeptin levels or poor kisspeptin signaling can delay or prevent the onset of puberty. Other problems connected to high or low kisspeptin levels are still being discovered and researched.

If you are struggling with fertility, kisspeptins may be one of the reasons. Talk to your healthcare provider about your kisspeptin levels, and learn whether kisspeptin treatment could potentially help.

Oxytocin is a hormone produced by the hypothalamus and secreted by the pituitary gland. This important hormone plays a crucial role in the childbirth process and also helps with male reproduction. Understanding oxytocin will help you take better care of your health and lead you toward a better understanding of how your body functions.

In women, oxytocin is responsible for signaling contractions of the womb during labor. The hormone stimulates the uterine muscles to contract, so labor begins. It also increases the production of prostaglandins, which move labor along and increases the contractions even more. Because of this effect, synthetic oxytocin (pitocin) is sometimes used to induce a woman to start labor if she cannot start naturally, or it can be given to make contractions stronger if a woman's labor is slowing.

Once the baby is born, oxytocin promotes lactation by moving the milk into the breast. When the baby sucks at the mother's breast, oxytocin secretion causes the milk to release so the baby can feed. At the same time, oxytocin is released into the brain to stimulate further oxytocin production. Once the baby stops feeding, the production of the hormone stops until the next feeding.

For men, oxytocin function is less important, but it does have a role to play in moving sperm. It also appears to affect the production of testosterone in the testes.

Studies of oxytocin also have found that it is an important chemical messenger that controls some human behaviors and social interaction. It is oxytocin that triggers the bond between a mother and an infant, and it may also play a role in recognition, sexual arousal, trust, and anxiety. Some research shows that the hormone may affect addiction and stress as well.

How is Oxytocin Production Controlled?

Oxytocin production is controlled by a positive feedback mechanism. This mechanism allows the release of the oxytocin hormone when a trigger occurs. The hormone then causes an action in the body, such as the letdown of milk or the start of labor contractions, which signals more production of oxytocin. The feedback cycle continues until the action, such as childbirth or feeding the baby, is complete.

Problems with Oxytocin Production

High and low oxytocin levels are possible, but research has not yet found any implications of these conditions. Men with high levels of oxytocin sometimes develop benign prostatic hyperplasia, or the enlarging of the prostate gland. This condition can cause urinary complaints. A lack of oxytocin can prevent the milk letdown reflex and make breastfeeding difficult. Low oxytocin levels have also been linked to depression, but using oxytocin to treat mental health conditions has not yet been studied sufficiently.

If you have further questions about oxytocin, or simply want to ensure that your hormones are functioning properly, you need the services of an endocrinologist.

Gonadotrophin-releasing hormone (GnRH) is produced from cells in the hypothalamus. It is then released into small blood vessels that carry the hormone to the pituitary gland. As a consequence, the pituitary gland produces luteinizing hormone (LH) and follicle-stimulating (FSH) hormones. These hormones, LH and FSH, are essential to male and female reproductive health. GnRH causes the pituitary gland to secrete LH and FSH.

In childhood, GnRH levels are low. As puberty begins, GnRH levels start to rise. When the testes and ovaries are fully developed, GnRH, LH, and FSH production are controlled by the levels of testosterone and female sex hormones (estrogen and progesterone). In women, FSH encourages eggs to grow in the ovaries. Leading to the production of estrogen, which signals to the pituitary gland to decrease the release of FSH and to produce more LH, causing ovulation and FSH and LH levels to drop. In men, GnRH stimulates the production of LH from the pituitary gland. LH attaches to receptor cells in the testes, which starts the production of sperm cells.

What Problems Can Occur with GnRH?

Research is still being conducted on the effects of having too much GnRH. In rare cases, pituitary tumors can develop, which increases the production of gonadotropins (LH and FSH), which might cause the body to overproduce testosterone and estrogen. If GnRH levels are too low, it often means that a person does not begin puberty. Kallmann’s Syndrome is an condition where gonadotropin levels are low due to inadequate GnRH levels. This condition is more common among men and is accompanied by a decreased sense of smell. Also, damage to the hypothalamus can halt GnRH production. This will also stop the regular production of FSH and LH. This may lead to amenorrhea in women, loss of sperm production in men, and loss of hormones made from the ovaries or testes.

Pineal Hormones

Melatonin is created by the pineal gland in the brain. In a healthy, normally functioning individual, melatonin is released in a rhythmic cycle, with more melatonin produced at night when the light entering the eyes starts to diminish. The bloodstream carries it to the different areas of the body, where receptors pick up the melatonin to signal the need for sleep. 

Melatonin is essential to signaling the relaxation and lower body temperature that help with restful sleep. Levels of melatonin are higher at night, signaling the body that it is time to rest. In animals, the hormone also regulates seasonal biology, such as the reproductive system, winter coat growth, and hibernation behaviors. A connection between melatonin and human reproduction or seasonal cycles has not yet been established. Because it is so connected to sleep, melatonin has been called the "sleep hormone." However, it is not necessary for sleep, and people can sleep with inadequate levels of melatonin in the body. That said, the secretion of melatonin does allow individuals to sleep better.

Problems Connected with Melatonin

People do not experience problems with melatonin secreted naturally by the body. The amount of melatonin produced by the body, whether low or high, is not associated with any health problems. In fact, in a lifetime, melatonin levels increase and decrease during the various stages of life. Low levels of melatonin do not appear to have any serious effects on health — although it can make sleep difficult to achieve if the levels change.

However, melatonin supplementation as a sleep aid is popular, and sometimes people will take too much melatonin. This can cause drowsiness and a reduced core body temperature. Extremely high levels of melatonin can also contribute to headaches and fatigue. It's also possible for very large doses of melatonin to affect human reproduction.

If you are considering taking melatonin supplements to help with sleep, consider asking your healthcare provider:

  • How much melatonin do I need?
  • How much melatonin is too much?
  • How long can I take melatonin safely?
  • Is long-term melatonin use dangerous?

How Does the Body Uses Serotonin?

Mood: Serotonin is in the brain. It is thought to regulate mood, happiness, and anxiety. Low levels of serotonin are linked to depression, while increased levels of the hormone may decrease arousal.

Bowel Movements: Serotonin is found in your stomach and intestines. It helps control your bowel movements and function.

Nausea: Serotonin is produced when you become nauseated. Production of serotonin increases to help remove bad food or other substances from the body. It also increases in the blood, which stimulates the part of the brain that controls nausea.

Sleep: Serotonin is responsible for stimulating the parts of the brain that control sleep and waking. Whether you sleep or wake depends on the area is stimulated and which serotonin receptor is used.

Blood Clotting: Serotonin is released to help heal wounds. Serotonin triggers tiny arteries to narrow, which helps forms blood clots.

Bone Health: Having very high levels of serotonin in the bones can lead to osteoporosis, which makes the bones weaker.

Mental Health: Serotonin helps regulate your mood naturally. When your serotonin levels are at a normal level, you should feel more focused, emotionally stable, happier, and calmer.

What Problems are Associated with Low Levels of Serotonin?

Low levels of serotonin are often associated with many behavioral and emotional disorders. Studies have shown that low levels of serotonin can lead to depression, anxiety, suicidal behavior, and obsessive-compulsive disorder. If you are experiencing any of these thoughts or feelings, consult a health care professional immediately. The sooner treatment starts, the faster you’ll see improvements.

What Problems are Associated with High Levels of Serotonin?

Serotonin syndrome can occur when you take medications that increase serotonin action leading to side effects. Too much serotonin can cause mild symptoms such as shivering, heavy sweating, confusion, restlessness, headaches, high blood pressure, twitching muscles, and diarrhea. More severe symptoms include high fever, unconsciousness, seizures, or irregular heartbeat. Serotonin syndrome can happen to anyone, but some people may be at higher risk. You are at a higher risk if you increased the dose of medication that is known to raise serotonin levels or take more than one drug known to increase serotonin. You may also be at risk if you take herbal supplements or an illicit drug known to increase serotonin levels.

If you suspect that your serotonin levels are too high or low, the first step is to speak with a health care professional.

Consider asking your doctor:

  • Is my medication causing serotonin syndrome?
  • If I am experiencing feelings of depression, are my serotonin levels too low?
  • Are my levels of serotonin affecting any other aspects of my health?

Pituitary Hormones

Adrenocorticotropic hormone (ACTH) plays a large role in how your body responds to stress. ACTH is produced in the pituitary gland, its production stimulates the production and release of cortisol from the adrenal gland. After ACTH is made in the pituitary gland, ACTH is released into the bloodstream and travels around the body. Production of ACTH is regulated by corticotrophin-releasing hormone (CRH) from the hypothalamus and cortisol from the adrenal gland. If ACTH levels are low, the hypothalamus releases CRH which is key to the stress hormone system and acts on many areas of the brain such as appetite and memory. Once the CRH is discharged, it triggers the pituitary gland to secrete ACTH.

High levels of ACTH are detected by the adrenal gland, which starts the production of cortisol. When cortisol levels rise in the body, the brain can sense these high levels and the production of the CRH and ACTH decreases. Stress activates ACTH production and increases cortisol levels.

What Problem Can Occur With ACTH?

If too much ACTH is produced, this can lead to high levels of cortisol in the body, also known as Cushing syndrome. The most common cause of increased ACTH production is a benign pituitary tumor.  When this is present, the disorder is called Cushing disease. Other endocrine conditions that may lead to an increase of ACTH include adrenal insufficiency and congenital adrenal hyperplasia.

Having lower than normal ACTH levels in the blood can be a result of other endocrine conditions such as Cushing syndrome or hypopituitarism. 

ACTH Testing
To diagnose these conditions, healthcare providers can order an ACTH blood test. An ACTH test is ordered if a cortisol blood test has abnormal results or if a patient has symptoms of too much or too little cortisol. Analyzing ACTH and cortisol levels together can help identify the different endocrine conditions associated with high and low cortisol levels. To test ACTH levels, healthcare providers may require you to fast overnight and conduct the test early in the morning. This is because ACTH levels are high in the morning and gradually decrease during the day. ACTH is at its lowest level during sleep. 

Human growth hormone (GH) is a substance that controls your body’s growth. GH is made by the pituitary gland, located at the base of the brain. GH helps children grow taller (also called linear growth), increases muscle mass, and decreases body fat. In both children and adults, GH also helps control the body’s metabolism—the process by which cells change food into energy and make other substances that the body needs.

If children or adults have too much or too little GH, they may have health problems. Growth hormone deficiency (too little GH) and some other health problems can be treated with synthetic (manufactured) GH. Sometimes GH is used illegally for non-medical purposes.

How is Growth Hormone Therapy Used?

The U.S. Food and Drug Administration (FDA) has approved GH treatment for certain conditions. GH is available only by prescription and is injected. Synthetic GH seems to be safe and effective when used as prescribed for the FDA-approved conditions.

In children, GH is used to treat:

Growth hormone deficiency
Conditions that cause short stature (being shorter than children of the same age), such as chronic kidney disease, Turner syndrome, and Prader-Willi syndrome

In adults, GH is used to treat:

Growth hormone deficiency
Muscle wasting (loss of muscle tissue) from HIV
Short bowel syndrome

Some companies sell human GH pills or GH releasers, claiming that the pills are “anti-aging” substances. But these substances have not been proven to increase the body’s production of GH or to fight aging, increase muscle, or provide other benefits. GH has no effect if it is taken as a pill because it is inactivated (loses its action) during digestion.

In addition to these uses, doctors outside and a number within the U.S. sometimes prescribe GH for other health problems. (When doctors prescribe medicines for conditions other than the ones officially approved, the process is called “off-label” use.)

If you’re worried about GH deficiency in yourself or a family member, talk with a doctor.

Is Growth Hormone Use Appropriate for Healthy Adults?

Studies of healthy adults taking GH have produced conflicting results. Some short-term studies showed that older adults increased their endurance and strength, with increased muscle and decreased fat mass. But other studies did not show similar benefits. More studies are needed to fully understand the benefits and risks of GH use in healthy adults.

Aside from its use in research studies, prescribing or using GH off-label is illegal in the US. Adults can achieve improved health, body composition, strength, and endurance by following a healthy diet and getting frequent exercise.

How is Growth Hormone Abused?

People sometimes take GH illegally to stop or reverse the effects of aging or to improve athletic performance. Some athletes believe taking GH alone will not achieve the desired results, so they take it along with anabolic (tissue building) steroids in an effort to build muscle, increase strength, and decrease body fat. Some athletes also use insulin to increase the muscular effects of GH, which is a dangerous practice because it lowers blood sugar.

What Are the Risks of Growth Hormone Abuse?

People can experience harmful side effects when they abuse GH. Side effects of short-term use include joint and muscle pain, fluid build-up, and swelling in the joints. If GH is injected with shared needles, people may be exposed to HIV, AIDS, or hepatitis. Taking high doses of GH over a long time may contribute to heart disease.

GH sold illegally may contain unknown and potentially harmful ingredients. For instance, if people take GH derived from human tissue, they risk developing a fatal brain disease called Creutzfeldt-Jakob disease, which is similar to mad cow disease. Consider asking your healthcare provider:

  • Do I (or my child) need human growth hormone treatment for medical reasons?

  • What are the benefits and risks of growth hormone treatment?

  • What are the signs of growth hormone abuse?

  • Should I see an endocrinologist about my condition?

Human Chorionic Gonadotropin (hCG) hormone is important in the early stages of pregnancy. It is produced by cells that are surrounding a growing embryo, which eventually forms the placenta. hCG can be detected in your body as early as 1 week after an egg is fertilized, which forms the basis of most over the counter pregnancy tests. hCG also ensures the corpus luteum, a temporary endocrine gland a woman’s body produces after ovulation, continues to produce progesterone during the first trimester of pregnancy. Low concentrations of hCG  are also produced by the pituitary gland, thus, men and non-pregnant women still have detectable levels of HcG throughout their lives.

The levels of hCG increases every two to three days as your embryo continues to develop. hCG levels peak around the sixth week of pregnancy. Afterwards, hCG will be found in your body, but the levels will begin to decrease. Once the placenta is fully formed, it serves as a source of progesterone production and assistance from hCG to support ovarian function is no longer essential.

What Problems can Occur with hCG?

Very high hCG levels are rare. In these cases, it may be sign of a molar pregnancy, which is an abnormal growth of cells that usually develop in the placenta. In people who are not pregnant, high hCG levels may be due to certain cancers such as breast, kidney, and lung. Low levels of hCG may be a sign of a miscarriage or another problem within the pregnancy, such as the embryo implanting outside of the uterus. Consider asking your healthcare provider:

  • How early can doctors detect my hCG levels?

  • What test is the best way to detect pregnancy?

  • Why is hCG important in the early stages of my pregnancy?

Luteinizing hormone (LH) is produced and released in the anterior pituitary gland. This hormone is considered a gonadotrophic hormone because of its role in controlling the function of ovaries in females and testes in males, which are known as the gonads.

In women, the hormone stimulates the ovaries to produce oestradiol. Two weeks into a woman's cycle, a surge in luteinizing hormone causes the ovaries to release an egg during ovulation. If fertilization occurs, luteinizing hormone will stimulate the corpus luteum, which produces progesterone to sustain the pregnancy.

For men, luteinizing hormone stimulates the production of testosterone from Leydig cells in the testes. Testosterone, in turn, stimulates sperm production and helps accentuate male characteristics — like a deep voice or growth of facial hair.

What Problems Can Occur With Luteinizing Hormone?

People who have high levels of luteinizing hormone may experience infertility, because the hormone directly impacts the reproductive system. In women, luteinizing hormone levels that are too high are often connected to polycystic ovary syndrome, which creates inappropriate testosterone levels. Some genetic conditions, like Turner syndrome or Klinefelter syndrome, can cause high levels of the hormone, as well. People with these conditions are often unable to reproduce.

Low levels of luteinizing hormone can also cause infertility, because insufficient levels will limit the production of sperm or the ovulation process. Too little luteinizing hormone stops ovulation in women or creates a deficiency in gonadotrophin-releasing hormone (GnRH) secretion in men.

If you are struggling with infertility or other reproductive-system complaints, poor luteinizing hormone levels. Consider your healthcare provider:

  • What hormone imbalances could be affecting my fertility?

  • What blood tests should I have to determine the hormones that are not in proper balance?

  • Is there any way to treat these imbalances?

  • How can I support a better hormone balance naturally?

Prolactin, as its name implies, is a hormone that promotes lactation (breast milk production) in mammals and is responsible for a number of other functions and systems. Prolactin is created in the front portion of the pituitary gland in your brain, as well as in the uterus, brain, breasts, prostate, adipose tissue, skin, and immune cells.

Prolactin (also known as luteotropin) function is still being studied, but research seems to show a variety of purposes for this hormone. For instance, it also regulates behavior, the immune system, metabolism, reproductive systems, and many different bodily fluids. This makes it a crucial hormone for overall health and well-being, for both men and women. Production of prolactin is controlled by two main hormones: dopamine and estrogen. These hormones send a message to the pituitary gland primarily indicating whether to begin or cease the production of prolactin. Dopamine restrains the production of prolactin, while estrogen increases it.

Possible Problems with Prolactin Production

For most people, prolactin does its job without a problem, and few are aware of the impact it has on their health. Yet some people can struggle with prolactin levels, which can cause a variety of problems.Too much prolactin in the blood causes hyperprolactinemia, a condition that can lead to menstrual disturbances, estrogen deficiency and testosterone deficiency. High prolactin levels also can cause unwanted lactation. This often occurs during pregnancy or when the thyroid is not functioning properly. Pituitary tumors, known as prolactinomas, and medications that reduce dopamine can also lead to increased prolactin levels. High levels of prolactin are linked to sexual problems. Some of these conditions can be treated with medications that mimic the action of dopamine.

It's also possible to have too little prolactin, a condition known as hypoprolactinaemia. This is extremely rare, but it can occur if people have under-active pituitary glands. This is commonly noticed in women after pregnancy who are not able to produce sufficient milk. No other proven health effects of low prolactin levels have been noted. Research is underway to determine if those with low prolactin levels suffer from a reduction in immune system responses.

Prolactin is an important, yet not often well-known, hormone. Take control of your health by understanding your hormones and how they affect you. If you are concerned about prolactin levels or functions, consider asking your healthcare provider:

  • Is prolactin affecting my ability to produce milk?

  • How can I raise or lower my prolactin levels?

  • What concerns are there surrounding prolactin?

  • How can I monitor prolactin levels?

Image of menopause coloring pad.

Return to Hormones and Endocrine Function>>>

Last Updated:
Patient Resource

Find an Endocrinologist

Multiple doctors smiling
Our physician referral directory is comprised of over 6,500 members of the Society. The referral is updated daily with clinicians who are accepting new patients.
Patient Resource

Find an Endocrinologist

Our physician referral directory is comprised of over 6,500 members of the Society. The referral is updated daily with clinicians who are accepting new patients.

Back to top

Who We Are

For 100 years, the Endocrine Society has been at the forefront of hormone science and public health. Read about our history and how we continue to serve the endocrine community.