ALL YOU NEED TO LEARN ABOUT HORMONES
The endocrine system (hormones) has different glands that release various hormones. This system, similar to the nervous system helps one part of the body (the gland) to communicate with another part of the body (the target cell) to perform different functions.. The endocrine glands are important for reproduction, metabolism, growth and other functions.
This system uses hormones to control and coordinate the body’s homeostasis and regulate reproduction, energy level, growth and development, and respond to various environmental stimuli
– Adrenal Glands
Hormone function: Life saving hormone; functions as anti-inflammatory; regulates blood pressure , blood glucose levels and muscle strength apart from supporting salt and water balance
Regulates water balance, salt, and BP
Causes rapid heart rate, promotes oxygen intake and blood flow
Maintains blood pressure along with other hormones
Growth hormone releasing hormone (GHRH)
Hormone Function:Maintains homeostasis by regulating growth hormone release in the pituitary gland
Thyrotropin Releasing Hormone (TRH)
Hormone Function: Maintains homeostasis by regulating thyroid stimulating hormone release in the pituitary gland
Gonadotropin Releasing Hormone (GnRH)
Hormone Function: Maintains homeostasis by regulating LH/FSH production in the pituitary gland
Corticotropin Releasing Hormone (CRH)
Hormone Function: Maintains homeostasis by regulating adrenocorticotropin release in the pituitary gland
– Pituitary Gland
Antidiuretic Hormone (ADH) (vasopressin)
Hormone Function: Supports water retention from kidneys and controls blood pressure
Adrenocorticotropic Hormone (ACTH)
Hormone Function: It regulates levels of the steroid hormone cortisol, which isreleased from the adrenal glands.
Growth Hormone (GH)
Hormone Function: Regulates growth and development; also stimulates protein production and influences fat distribution
Hormone Function: Controls production of sex hormones, estrogen in women and testosterone in men and supports the production of eggs and sperms.
Hormone Function: Stimulates contraction of uterus and milk ducts in the breast during pregnancy and labour.
Hormone Function: Initiates and maintains milk production in mothers; impacts sex hormone levels and interferes with periods.
Thyroid-Stimulating Hormone (TSH)
Hormone Function: Stimulates the secretion of thyroid hormones from the thyroid gland
Renin and Angiotensin
Hormone function: Controls blood pressure directly and by regulating aldosterone production from the adrenal glands
Hormone Function: Red blood cell (RBC) production
Hormone Function:Raises blood sugar levels and regulates glucose homeostasis
Hormone Function:Anabolic hormone, Lowers blood glucose; promotes metabolism of glucose, protein, and fat
Hormone Function:Promotes female sexual characteristics and reproductive development, influences functioning of uterus and growth of breasts and protects bone health
Hormone Function:Helps proliferate endothelium (inner lining of the uterus), facilitates fertilization; supports milk production
Parathyroid Hormone (PTH)
Hormones Function: Important regulator of blood calcium levels along with Vitamin D
Hormone Function: Controls metabolism; also affects growth, maturation, nervous system activity, and metabolism
Hormone Function: Helps develop the lymphoid system
Hormone Function: Develop and maintain male sexual characteristics and promotes libido.
Hormone Function: Releases melatonin during night and facilitates sleep
Adipose tissue (body fat) although crucial for health and needed for storing and releasing energy to fuel the body, adipose tissue is also an important endocrine organ releasing important hormones like leptins, adiponectins or aromatases etc.
The adrenal are endocrine glands at the top of each kidney. They constitute the outer adrenal cortex and inner adrenal medulla.. They produce life saving hormones like cortisol and many others like catecholamines, aldosterone and others.
The hypothalamus is a part of the brain lying below thalamus and above the pituitary to which it is connected with a stalk. the major function of the hypothalamus is to maintain homeostasis by controlling the release of hormones from the pituitary gland.
The kidneys are excretory organs that ensure that unwanted substances and excess water are removed from the bloodstream. However, it does function as endocrine gland in some ways. The kidneys make two main hormones, vitamin D, erythropoietin and some prostaglandins.
The ovaries produce and release eggs for fertilisation. They also produce the female hormones oestrogen and progesterone under the influence of gonadotrophins.
The pancreas serves two important purposes, one as part of digestive system and the other as endocrine organ producing hormones whether insulin, glucagon, somatostatin or many others.
The parathyroid glands are situated on the rear side of the thyrod, a rice grain sided gland in the neck and helps control the levels of calcium in the blood.
The pineal gland is situated in the epithalamus, where the two halves of the brain join. Pineal gland remains the major site of the body’s melatonin production.
The pituitary gland is a small pea-sized master gland and controls the activity of most endocrine systems. Pituitary gland influences the functioning of adrenal glands, thyroid gland, ovaries and testes.
The placenta is a endocrine organ of pregnancy. Placental hormones help maintain healthy pregnancy, prepare for labour and facilitate breastfeeding.
The testes are male reproductive glands that produce sperm and the hormone testosterone. Apart from testosterone which is produced by Leydig cells, testes also produce inhibin B and anti-Müllerian hormone from Sertoli cells and IGF- 3 and oestradiol from Leydig cells.
The thyroid gland is responsible for producing thyroid hormones into the bloodstream and regulated by hypothalamic pituitary axis. The thyroid gland also produces calcitonin.
Acromegaly is a condition caused by a tumour of the pituitary gland leading to overproduction of growth hormone. Acromegaly manifests with signs and symptoms of increase in size of hands and feet, a change in the appearance of the face and enlargement and damage of internal organs.
Addison’s disease is caused by primary adrenal insufficiency due to failure of the adrenal glands, leading to steroid deficiencies. The damage is usually autoimmune or due to metastases or TB or adrenal glands. Prompt steroid replacement is needed to prevent deaths.
Adult Onset Growth Hormone Deficiency
Adult onset growth hormone deficiency is when the pituitary gland is damaged due to tumour or its treatment usually causing low GH and IGF-1. It can be treated with growth hormone therapy when required.
Amenorrhoea is when women stops having ‘periods(menstrual cycles) . Primary amenorrhoea is physiological and around 50 years of age while secondary amenorrhoea could be due to pathological causes.
Carcinoid tumours are slow-growing neuroendocrine tumours that arise from specialised cells that release hormones.
Childhood onset growth hormone deficiency is a when pituitary gland stops producing growth hormone during childhood. This can majorly impact height unless early diagnosis and treatment initiated.
Chronic Fatigue Syndrome
Chronic fatigue syndrome is a condition that causing long-term fatigue and tiredness. Unless general tiredness this condition does not improve with rest or sleep. This condition is also called myalgic encephalopathy( ME) or post-viral fatigue syndrome.
Circadian Rhythm Sleep Disorders
Circadian rhythm sleep disorders leads to abnormal sleep patterns, sleep loss and fatigue due to circadian clock in the brain is not synchronised with ‘real’ local time.
Congenital Adrenal Hyperplasia
Congenital adrenal hyperplasia is an inherited condition causing a deficiency in cortisol levels and increased androgens. This usually results in male characteristics in females and or precocious puberty.
Craniopharyngiomas are slow-growing benign brain tumours adjacent to the pituitary gland causing compressive symptoms and hypopituitarism.
Cushing’s disease is the collection of clinical symptoms and signs resulting from a pituitary tumour that causes excessive amounts of the hormone cortisol to be released by the adrenal glands.
Cushing’s syndrome is when the body is exposed to too much of cortisol whether iatrogenic or due to pituitary or adrenal tumours.
Diabetes insipidus is different from Diabetes Mellitus and is a rare condition caused by a reduction anti-diuretic hormone resulting in excess dilute urine with increased thirst.
Diabetes mellitus is the commonest endocrine disorder caused by high glucose due to deficient or ineffective insulins.
Eating disorders are psychological disorders leading to unhealthy eating habits, and can be treated in many cases by psychological interventions.
Empty Sella Syndrome
Empty sella syndrome is the term used to describe the appearance of a small or absent pituitary gland on pituitary imaging. Most patients have no symptoms, and generally, no treatment is required. If hormone deficiencies are present, replacement therapy should be considered.
Endometrial cancer is a form of cancer that originates from the tissue that lines the womb. This tissue is called the endometrium.
Endometriosis causes painful monthly periods as the lining of the womb called the endometrium grows outside of the womb. It can be one of the causes for infertility or chronic pelvic pain.
Familial Medullary Thyroid Cancer
Medullary thyroid cancer is a rare inherited form of thyroid cancer, which in 20% of cases runs in families.
Female infertility is when a woman is unable to conceive a child after 12 months of regular intercourse with her male healthy fertile partner without the use of contraception.
Gastrinomas also known as Zollinger-Ellison syndrome are neuroendocrine tumours that are usually found in the first part of the small intestine or in the pancreas, which produce excess secretion of gastrin causing peptic ulcer disease withhypercalcemia and diarrhoea.
Gender Identity Disorder
Gender identity disorder is under recognised condition called by various names like Gender dysphoria; transsexualism; male to female (MtF) transsexual; female to male (FtM) transsexual; trans man; trans woman; transman; transwoman. With this condition the person is unhappy with the gender they were born in and they feel that they belong to the opposite gender.
Gestational diabetes is high glucose levels during pregnancy seen among one in five pregnancies in Indian women. Strict blood glucose control in improves outcomes of pregnancy.
Non-functioning pancreatic NETs
Neuroendocrine tumours (NETs) are usually non functional pancreatic tumours from specialised cells of the pancreas. There are also functioning neuroendocrine tumours, such as insulinoma, gastrinoma or somatostatinoma which show symptoms of excess hormone production.
Non-functioning pituitary tumours
Pituitary tumours that do not produce any hormones are called as Non-functioning ones. They are usualy benign tumours in the pituitary gland and present with local compressive symptoms like impaired vision or hormone deficiencies.
Obesity is a state of excess body fat and can reduce both quality and length of life.
Osteoporosis is a bone thinning disorder caused by loss of bone mass and increasing the risk of fracture. In women, its usually post menopausal while there are many hormonal causes for osteoporosis.
Paget’s disease is a common bone conditon usually asymptomit or it may at time present with pain, deformity or bone fractures. Bisphosphonates are the main stay of treatment at present.
Paragangliomas or extra-adrenal phaeochromocytomas are a rare type of tumours arising from specialised nerves that control blood pressure, the sympathetic and parasympathetic nervous system. Paragangliomas can occur in the head & neck or even inthe chest or abdomen.
A phaeochromocytoma is a tumour from zona medullaris of the adrenal gland that produces excess amounts of hormones such as adrenaline and noradrenaline. Phaeochromocytomas and paragangliomas are sometimes collectively referred to as chromaffin tumours
Pituitary apoplexy is a medical emergency caused by a bleed or an infarct in the pituitary gland, most commonly in a pituitary tumour. Sheehan’s syndrome, a pituitary infarct seen in women immediately after delivery is a form of pituitary apoplexy.
Polycystic ovary syndrome
Polycystic ovary syndrome also referred to as Stein-Leventhal syndrome; PCOS is one of the most common endocrine disorder in Indian women of reproductive age. It presents as a cohort of symptoms including irregular periods, hirsuitism, hair loss, acne, weight gain and remains the major cause for infertility in women. Hormonal imbalance of sex hormones particularly of oestrogen and testosterone is common.
Prader-Willi syndrome is a genetic disorder affecting the hypothalamus and pituitary gland, leading to excess hunger and obesity, hormonal imbalances, developmental delay and learning difficulties.
Pre-eclampsia is a complication of pregnancy whether the mother develops very high blood pressure and protein in her urine leading to adverse outcomes for both mother and child.
Precocious puberty is when early development of secondary sexual characteristics is seen before the age of nine years in boys and before eight years of age in girls. For girls the changes are of development of breasts, pubic and axillary hairs before eight years of age, or starting periods before nine years of age. In boys enlargement of testicles and penis with pubic and axillary hair before nine years of age is considered precocious.
Premature ovarian failure
premature ovarian failure is when ovaries stop working with no subsequent periods roughly before the age of 40 years. menopause usually occurs around the age of 50.
Premenstrual syndrome affects women few days prior to her monthly periods and settles after it. This not so uncommon condition does cause significant distressing physical and psychological problems.
Primary hyperaldosteronism is a common cause of secondary hypertension where adrenal glands produce excess amounts of aldosterone. This causes sodium retention and high blood pressure.
Gigantism is a childhood or adolescence condition caused by growth hormone-secreting pituitary tumour leading to accelerated growth caused by excessive amounts of growth hormone secretion.
Glucagonoma is a tumour of the pancreas with increase levels of glucagon presenting with skin rash and raised blood sugar levels. These are pancreatic neuroendocrine tumours secreting glucagon from the pancreatic islet alpha cell tumours.
Goitre is an enlarged thyroid gland. These goitres could be nodular or uniform, can present has hypothyroid , euthyroid or hyperthyroid and sometimes can be cancerous and is treated in a variety of different ways.
Graves’ disease is an autoimmune thyroid disease with excess production of thyroid hormone resulting in hyperthyroidism.
Hashimoto’s disease is an autoimmune disease and is the most common cause for hypothyroidism caused by inflammation of the thyroid gland due to anti thyroid antibodies.
Hirsutism is the presence of excess male pattern hair growth in women and is commonly caused by polycystic ovarian disease or at times idiopathic in nature.
Hypercalcaemia is the presence of abnormally high calcium levels in the blood which could be PTH driven as seen in hyperparathyroidism or due to malignancies apart from other causes like medications, Vit D toxicity etc.
Hyperthyroidism is common where the thyroid gland becomes overactive and produces excess thyroid hormone. It could be caused by various reasons and treatment is usually medication, RAI or surgery based on individual patient.
Hypocalcaemia is when calcium levels in the blood are low caused by either vitamin D deficiency or hypoparathyroidism.
Hyponatraemia happens when sodium levels are low in blood. Hyponatraemia is also dependent on the fluid status, whether dehydrated, fluid overloaded or due to SIADH in euvolemic state.
Hypoparathyroidism is a rare condition characterised by inadequate parathyroid hormone production from the parathyroid glands, resulting in low calcium levels in the bloodstream.
Hypophosphataemia or low levels of phosphate in the blood is usually due to hyperparathyroidism or vitamin D deficiency.
Hypopituitarism is the failure of production of hormones from the pituitary gland. It can be panhypopituitarism where all pituitary hormones are deficient or partial hypopituitarism where some are deficient.
Hypothyroidism or underactive thyroid is a condition when thyroid gland is unable to produce enough thyroid hormones. In severe forms it can lead to the rare emergency of myxoedema and coma.
An insulinoma is a beta cell tumour that occurs in the pancreas secreting too much insulin and causing life threathening hypoglycaemia.
Klinefelter’s syndrome or 47 XXY syndrome is a genetic condition in boys that happens as a result of the presence of one or more extra X chromosomes. Klinefelter’s syndrome presents with tall stature, reduced fertility and gynaecomastia, although in some there may be no clinical features other than reduced sperm count.
Male hypogonadism is due to low testosterone levels and can lead to loss of sex drive, delayed puberty and with low or absent sperm production from testes.
The menopause is the time for the end of woman’s reproductive age and usually is around 50 years. This is when menstruation stops because the ovaries stop producing hormones and releasing eggs for fertilisation.
Mulrinodular goitre is an enlarged goitre with nodularity due to multiple lumps in the thyroid gland. Though in most situations the thyroid function may remain intact, however, this condition can also present with hypothyroidism or hyperthyroidism. Multinodular goitres are usually benign but can rarely harbour malignant tumours.
Multiple Endocrine Neoplasia Type 1
Multiple endocrine neoplasia type 1 or wermer’s syndrome is a rare autosomal dominantly inherited disease resulting in tumours of the pituitary, parathyroid glands and pancreas. Usually presents in families with hypercalcemia.
Multiple Endocrine Neoplasia Type 2A
Multiple endocrine neoplasia type 2A (MEN2A) or Sipple’s syndrome is another inherited disease causing medullary carcinoma of thyroid, adrenal lesions like pheochromocytomas and parathyroid gland abnormalities like hyperparathyroidism.
Multiple Endocrine Neoplasia Type 2B
Multiple endocrine neoplasia type 2B (MEN2B) is another rare inherited condition similar to MEN Type 2A with tumours in the thyroid, adrenal and parathyroid glands and additionally there can be mucosal tumours.
Nelson’s syndrome is the condition that develops following bilateral adrenalectomy for Cushing’s disease caused by enlargement of the pituitary gland and tumour associated with excess secretion of ACTH. The patient presents with excessive pigmentation and visual loss due to large ACTH secreting pituitary adenoma.
Primary hyperparathyroidism is a common cause of hypercalcemia due to increase production of parathyroid hormone from the parathyroid glands. The usual cause is an adenoma of the parathyroid and rarely due to hyperplasia as part of MEN syndromes.
A prolactinoma is a benign adenoma of pituitary gland presenting with high levels of prolactin hormone. In women it presents with galactorrhea and secondary amenorrhoea while in men it could be with loss of libido, headache or tiredness.. It responds well to medication and surgery is limited to selected cases.
Resistance to thyroid hormone
Thyroid hormone resistance is a rare genetic condition when the thyroid hormone is effective on some body tissues . It may be associated with no symptoms or with sometimes present with symptoms of overactive and underactive thyroid.
Rickets is a condition seen in children due to vitamin D deficiency causing abnormal softening of the bones due to lack of minerals to strengthen it. However, a less severe condition is seen in adults and is known as osteomalacia.
Long term hypocalcemia can cause secondary hyperparathyroidism as the parathyroid glands release high levels of parathyroid hormone to control the levels of calcium in the blood.
Sheehan’s syndrome is a condition of the pituitary gland that occurs as a result of heavy bleeding during or after childbirth. This condition presents with lack of periods post delivery and inability to lactate as there is postpartum pituitary necrosis causing postpartum panhypopituitarism.
Turner syndrome is a common chromosomal disorder causing short stature, failure to enter puberty and infertility in girls. The prevalence is one in 2,500 girls. In half of these patients there is an entire X chromosome missing while in some others a milder version due to mosaicism
TSH secreting pituitary adenoma
TSH secreting pituitary adenomas are very rare and slow growing benign pituitary tumours . These adenomas produce thyroid stimulating hormone (TSH) and remain a very rare cause for hyperthyroidism. They are sometimes referred to as TSHomas.
Toxic thyroid nodule
Toxic thyroid adenoma results in excessive thyroid hormone production from solitary nodule of thyroid gland. The thyroid hormone production remains autonomously elevated resulting in hyperthyroidism.
Thyrotoxicosis is caused by excessive amount of thyroid hormones in the bloodstream while Hyperthyroidism is when thyroid gland becomes overactive and produces too much thyroid hormone.
Thyroid eye disease
Thyroid eye disease is an autoimmune condition also called as Graves ophthalmopathy, Thyroid eye disease; that affects the eyes causing swelling, inflammation and sometimes visual problems. Much worse in smokers and sometimes after radioactive iodine treatment for Graves Disease.
Thyroid cancers usually present as lumps in the thyroid gland and are generally curable with surgery. The survival rates are high compared to most other cancers. The common types of thyroid cancers are Papillary carcinoma, follicular carcinoma, medullary carcinoma, hurtle cell carcinoma or anaplastic thyroid cancer.
Tertiary hyperparathyroidism results after long term secondary hyperparathyroidism when the parathyroid glands become overgrown and remain permanently overactive. Hence tertiary hyperparathyroidism means excess production of parathyroid hormone causing hypercalcemia.
Somatostatinomas are rare types of functional pancreatic neuroendocrine tumour tumours that arise from specialised cells in the pancreas or sometimes from duodenum and produce excess somatostatin. They may present with abdominal pain and diarrhoea, prognosis is favourable if there is no spread to liver.