Hypothalamic and Pituitary Hormones

The hypothalamic and pituitary hormones are the most important regulators of the endocrine system. The hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus functions as the coordinating center between the CNS and endocrine system by integrating the signals received from the rest of the brain and releasing appropriate regulatory hormones to the pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland. The pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland then releases its own hormones in response to hypothalamic stimulation. Pituitary hormones regulate multiple endocrine organs, including the gonads, thyroid gland Thyroid gland The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland, adrenal glands Adrenal Glands The adrenal glands are a pair of retroperitoneal endocrine glands located above the kidneys. The outer parenchyma is called the adrenal cortex and has 3 distinct zones, each with its own secretory products. Beneath the cortex lies the adrenal medulla, which secretes catecholamines involved in the fight-or-flight response. Adrenal Glands, and mammary glands. Pituitary hormones also play a critical role in growth and water balance.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Overview

Definitions

Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview are messenger molecules that are synthesized in one part of the body and exert specific regulatory effects on another part of the body.

Hypothalamic hormones:

  • Secreted directly by neurons from the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus 
  • Act on the pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland
  • Represent the point of integration between the CNS and endocrine system

Pituitary hormones:

  • Secreted from both the anterior and posterior regions of the gland
  • Stimulate the secretion of hormones from peripheral endocrine organs
  • Regulated by both the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus and via negative feedback from peripheral endocrine hormones

Hypothalamic-pituitary axis and negative feedback

Many of the major endocrine hormones function within a multistep negative feedback loop known as an axis. These axes involve the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus, pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland, and multiple different peripheral endocrine glands.

General structure and function of an axis:

  • Hypothalamus secretes releasing hormones.
  • The releasing hormones are transported to specific target cells within the pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland.
  • The pituitary target cells release a 2nd hormone known as a tropic hormone.
  • Tropic hormones reach their target peripheral endocrine glands.
  • Peripheral endocrine glands secrete their hormones, which:
    • Act on target organs and exert a physiologic effect
    • Exert negative feedback on the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus and pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland
Endocrine axis-driven negative feedback loops

Endocrine axis-driven negative feedback loops

Image by Lecturio.

Example: hypothalamic-pituitary-thyroid (HPT) axis:

  • The hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus secretes thyrotropin-releasing hormone (TRH).
  • TRH stimulates pituitary thyrotropic cells to release thyroid-stimulating hormone (TSH).
  • TSH is transported to the thyroid to stimulate the production of thyroid hormones Thyroid hormones The 2 primary thyroid hormones are triiodothyronine (T3) and thyroxine (T4). These hormones are synthesized and secreted by the thyroid, and they are responsible for stimulating metabolism in most cells of the body. Their secretion is regulated primarily by thyroid-stimulating hormone (TSH), which is produced by the pituitary gland. Thyroid Hormones (e.g., thyroxine).
  • Thyroxine:
    • Stimulates metabolism in most cells in the body
    • Inhibits the release of TSH and TRH (negative feedback)

Hypothalamic Hormones

Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview are synthesized directly within the neurons of the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus. Hormones Hormones Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. Hormones: Overview are the primary regulators of the pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland, and thus, the primary mechanism by which the CNS communicates with the endocrine system.

Hypothalamic control of the anterior pituitary

The hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus secretes releasing factors that are transported to the anterior pituitary via the hypophyseal portal system (a vascular complex connecting the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus to the pituitary).

Stimulatory hypothalamic hormones:

  • TRH → stimulates pituitary thyrotropic cells to release TSH
  • Corticotropin-releasing hormone (CRH) → stimulates pituitary corticotropic cells to release adrenocorticotropic hormone (ACTH)
  • Gonadotropin-releasing hormone (GnRH) → stimulates pituitary gonadotropic cells to release:
    • Follicle-stimulating hormone (FSH)
    • Luteinizing hormone (LH)
  • Growth hormone-releasing hormone (GHRH) → stimulates pituitary somatotropic cells to release growth hormone (GH)
  • No “prolactin (PRL)-releasing hormone” has been definitively identified; PRL is primarily controlled through inhibition.

Inhibitory hypothalamic hormones:

  • Somatostatin:
    • At the anterior pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland, somatostatin inhibits:
      • GH
      • TSH
    • Inhibits additional hormones throughout the body
  • Dopamine:
    • Inhibits PRL release
    • Other functions: role in executive function, motor control, motivation, arousal, reinforcement, and reward

Hypothalamic control of the posterior pituitary

Unlike the anterior pituitary, there are no hypothalamic hormones released into the circulation to stimulate the posterior pituitary. Rather, the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus has axons directly connected to the posterior pituitary.

  • Posterior pituitary hormones are synthesized within the neurons in the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus.
  • Posterior pituitary hormones are transported down the neuronal axons, through the hypophyseal stalk, to the posterior pituitary.
  • The hormones are released into the circulation within the posterior pituitary.
Anterior and posterior pituitary gland

Diagrams of the anterior and posterior pituitary and their respective communication pathways with the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus

ADH: antidiuretic hormone
OT: oxytocin
Image: “Anterior and posterior pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland” by Phil Schatz. License: CC BY 4.0

Pituitary Hormones

The pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland is the “master gland” of the endocrine system. The pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland secretes hormones that stimulate other endocrine organs throughout the body.

Anterior pituitary

Anterior pituitary hormones include:

  • GH:
    • Does not target a specific organ
    • Stimulates cellular growth and differentiation throughout the body
    • Released from somatotropic cells (50% of anterior pituitary cells)
    • GH regulation:
      • Stimulated by GHRH
      • Inhibited by somatostatin
  • ACTH:
    • ACTH stimulates the adrenal cortex to secrete corticosteroids.
    • Released from corticotropic cells (15%–20% of anterior pituitary cells) 
    • Regulation: stimulated by CRH
  • TSH:
    • Stimulates the thyroid gland Thyroid gland The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland to release the thyroid hormones Thyroid hormones The 2 primary thyroid hormones are triiodothyronine (T3) and thyroxine (T4). These hormones are synthesized and secreted by the thyroid, and they are responsible for stimulating metabolism in most cells of the body. Their secretion is regulated primarily by thyroid-stimulating hormone (TSH), which is produced by the pituitary gland. Thyroid Hormones thyroxine and triiodothyronine
    • Released from thyrotropic cells (5% of anterior pituitary cells) 
    • Regulation: stimulated by TRH
  • Gonadotropins:
    • Act on the gonads (i.e., ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries and testes), stimulating them to secrete sex hormones:
      • Androgens Androgens Androgens are naturally occurring steroid hormones responsible for development and maintenance of the male sex characteristics, including penile, scrotal, and clitoral growth, development of sexual hair, deepening of the voice, and musculoskeletal growth. Androgens and Antiandrogens (e.g., testosterone)
      • Estradiol Estradiol The 17-beta-isomer of estradiol, an aromatized C18 steroid with hydroxyl group at 3-beta- and 17-beta-position. Estradiol-17-beta is the most potent form of mammalian estrogenic steroids. Menstrual Cycle
      • Progesterone
    • Released from gonadotropic cells (10% of anterior pituitary cells)
    • Regulation: stimulated by GnRH
    • The 2 gonadotropin hormones are:
      • FSH: stimulates the development of eggs in the ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries and sperm production in the testes
      • LH: stimulates ovulation in women and androgen production in both sexes
  • PRL:
    • Functions:
      • Stimulates the production (but not secretion) of breast milk during lactation
      • Has effects on LH sensitivity
    • Released from lactotropic cells (15%–20% of anterior pituitary cells)
    • Regulation:
      • Primarily regulated by dopamine (the major PRL inhibitor)
      • Stimulated by nipple stimulation

Posterior pituitary

Axons from the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus release these hormones directly into the circulation. The posterior pituitary hormones include:

  • Oxytocin:
    • Synthesized in the paraventricular nuclei of the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus
    • Stimulates:
      • Uterine contractions in labor Labor Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix, which culminates in expulsion of the fetus and the products of conception. Normal and Abnormal Labor
      • Milk let-down/secretion during lactation
    • Surges during sexual arousal and orgasm
    • May play a role in the propulsion of semen through the male reproductive tract
    • Known as the “love hormone”: Creates feelings of emotional bonding and sexual satisfaction
  • Antidiuretic hormone (ADH):
    • Synthesized in the supraoptic nuclei of the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus
    • Acts on the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys to increase water retention

Summary of the Hypothalamic-Pituitary Axis

Table: Hypothalamic-pituitary axis hormones and targets
Hypothalamic hormone Pituitary target cell Pituitary hormone Target organ End effects
CRH Corticotropes ACTH Adrenal cortex Release of corticosteroids
TRH Thyrotropes TSH Thyroid gland Release of thyroid hormones Thyroid hormones The 2 primary thyroid hormones are triiodothyronine (T3) and thyroxine (T4). These hormones are synthesized and secreted by the thyroid, and they are responsible for stimulating metabolism in most cells of the body. Their secretion is regulated primarily by thyroid-stimulating hormone (TSH), which is produced by the pituitary gland. Thyroid Hormones
GnRH Gonadotropes FSH Gonads: ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries, testes Development of ovarian follicles and production of sperm
LH Gonads: ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries, testes Androgen production (both sexes), stimulates ovulation (women)
GHRH Somatotropes GH Many organs Anabolic effects
Somatostatin (inhibitor) Somatotropes GH (inhibited) Many organs Anabolic effects inhibited with somatostatin
Dopamine (inhibitor) Lactotropes Prolactin (inhibited) Mammary glands Milk production inhibited with dopamine
ACTH: adrenocorticotropic hormone
CRH: corticotropin-releasing hormone
GH: growth hormone
GHRH: growth hormone-releasing hormone
FSH: follicle-stimulating hormone
LH: luteinizing hormone
TRH: thyrotropin-releasing hormone
TSH: thyroid-stimulating hormone

Clinical Relevance

  • Functional hypothalamic amenorrhea: a primary cause of secondary amenorrhea Secondary Amenorrhea Secondary amenorrhea is defined as the absence of menses for 3 months in a woman with previously regular menstrual cycles or for 6 months in a woman with previously irregular cycles. Etiologies involve either disruptions to the hypothalamic-pituitary-ovarian (HPO) axis or acquired obstructions in the uterus or outflow tract. Secondary Amenorrhea (cessation of menses Menses The periodic shedding of the endometrium and associated menstrual bleeding in the menstrual cycle of humans and primates. Menstruation is due to the decline in circulating progesterone, and occurs at the late luteal phase when luteolysis of the corpus luteum takes place. Menstrual Cycle). Functional hypothalamic amenorrhea results from the decreased pulsation of GnRH that occurs during times of severe physical or psychological stress and is most commonly associated with eating disorders or overexercise (common in women athletes). Management usually requires nutritional support and counseling.
  • Hypopituitarism Hypopituitarism Hypopituitarism is a condition characterized by pituitary hormone deficiency. This condition primarily results from a disease of the pituitary gland, but it may arise from hypothalamic dysfunction. Pituitary tumors are one of the most common causes. The majority of cases affect the anterior pituitary lobe (adenohypophysis), which accounts for 80% of the gland. Hypopituitarism: a condition characterized by a deficiency of all the pituitary hormones. As pituitary hormones regulate multiple organs, the effects of pituitary hypofunction are multisystemic. Causes include pituitary masses, congenital syndromes, trauma, infections, and vascular damage. Diagnosis is via a combination of clinical findings, hormone levels, provocation tests, and brain imaging. Treatment is by hormone replacement and addressing the underlying etiology.
  • Pituitary adenoma Pituitary adenoma Pituitary adenomas are tumors that develop within the anterior lobe of the pituitary gland. Non-functioning or non-secretory adenomas do not secrete hormones but can compress surrounding pituitary tissue, leading to hypopituitarism. Secretory adenomas secrete various hormones depending on the cell type from which they evolved, leading to hyperpituitarism. Pituitary Adenomas: tumors that develop within the anterior lobe of the pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland. Pituitary adenomas Pituitary adenomas Pituitary adenomas are tumors that develop within the anterior lobe of the pituitary gland. Non-functioning or non-secretory adenomas do not secrete hormones but can compress surrounding pituitary tissue, leading to hypopituitarism. Secretory adenomas secrete various hormones depending on the cell type from which they evolved, leading to hyperpituitarism. Pituitary Adenomas are classified by size (either micro- or macroadenomas) and their ability to secrete hormones. Nonfunctioning or nonsecretory adenomas do not secrete hormones but can compress the surrounding pituitary tissue and lead to hypopituitarism. Secretory adenomas secrete various hormones depending on the cell type from which they evolved, leading to hyperpituitarism.
  • Hyperprolactinemia Hyperprolactinemia Hyperprolactinemia is defined as a condition of elevated levels of prolactin (PRL) hormone in the blood. The PRL hormone is secreted by the anterior pituitary gland and is responsible for breast development and lactation. The most common cause is PRL-secreting pituitary adenomas (prolactinomas). Hyperprolactinemia: elevated levels of PRL in the blood. The most common cause is a PRL-secreting pituitary adenoma known as a prolactinoma. Presentations can include galactorrhea (milky discharge), oligomenorrhea, erectile dysfunction Erectile Dysfunction Erectile dysfunction (ED) is defined as the inability to achieve or maintain a penile erection, resulting in difficulty to perform penetrative sexual intercourse. Local penile factors and systemic diseases, including diabetes, cardiac disease, and neurological disorders, can cause ED. Erectile Dysfunction, and, in the case of large tumors, headaches and visual changes. Diagnosis is made by determining serum PRL levels and imaging the pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland. Management typically involves dopamine agonists as 1st-line therapy, although surgery and/or radiation may be required.
  • Acromegaly Acromegaly Acromegaly and gigantism are caused by an excessive production of growth hormone (GH) by the pituitary gland. Acromegaly is usually produced by pituitary tumors secreting GH or, less commonly, by extrapituitary disorders. Acromegaly and Gigantism and gigantism Gigantism Acromegaly and gigantism are caused by an excessive production of growth hormone (GH) by the pituitary gland. Gigantism typically results in children from excess GH before growth-plate closure; acromegaly typically results from excess GH after growth-plate closure. Acromegaly and Gigantism: conditions caused by the excess production of pituitary GH. Typically, gigantism Gigantism Acromegaly and gigantism are caused by an excessive production of growth hormone (GH) by the pituitary gland. Gigantism typically results in children from excess GH before growth-plate closure; acromegaly typically results from excess GH after growth-plate closure. Acromegaly and Gigantism refers to the tall stature seen in excess GH states in children before growth-plate closure. Acromegaly Acromegaly Acromegaly and gigantism are caused by an excessive production of growth hormone (GH) by the pituitary gland. Acromegaly is usually produced by pituitary tumors secreting GH or, less commonly, by extrapituitary disorders. Acromegaly and Gigantism is the result of excess GH after growth-plate closure, which leads to large extremities and characteristic facies. Diagnosis is by laboratory analysis and neuroimaging of the pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland.
  • Central diabetes insipidus Central Diabetes Insipidus Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of DI: central DI (CDI) and nephrogenic DI (NDI). In CDI, the amount of antidiuretic hormone (ADH) produced by the hypothalamus or released from the pituitary gland is decreased. Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus (CDI): a condition in which the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys are unable to concentrate urine due to a lack of circulating ADH. Low levels of ADH are due to either decreased production within the hypothalamus Hypothalamus The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Hypothalamus or decreased release from the posterior pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland. Individuals present with polyuria, nocturia, and polydipsia. Central and nephrogenic diabetes insipidus Nephrogenic Diabetes Insipidus Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of DI: central DI (CDI) and nephrogenic DI (NDI). In nephrogenic DI, the kidneys fail to respond to circulating ADH. Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus are differentiated based on ADH levels and response to the water-deprivation test. Treatment of CDI is with desmopressin.
  • SIADH SIADH Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a disorder of impaired water excretion due to the inability to suppress the secretion of antidiuretic hormone (ADH). SIADH is characterized by impaired water excretion leading to dilutional hyponatremia, which is mainly asymptomatic but may cause neurologic symptoms. S Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH): a disorder of impaired water excretion due to the inability to suppress ADH secretion. The inappropriate secretion of ADH can be due to various causes, including increased production by the pituitary gland Pituitary gland The pituitary gland, also known as the hypophysis, is considered the "master endocrine gland" because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. Pituitary Gland due to trauma or disease, certain medications, ectopic secretion in cancer, or hereditary causes (nephrogenic SIADH SIADH Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a disorder of impaired water excretion due to the inability to suppress the secretion of antidiuretic hormone (ADH). SIADH is characterized by impaired water excretion leading to dilutional hyponatremia, which is mainly asymptomatic but may cause neurologic symptoms. S Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)). Syndrome of inappropriate antidiuretic hormone should be suspected in any individual presenting with hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia, hypoosmolality, and high urine osmolality.

References

  1. Welk, C.K. (2021). Hypothalamic-pituitary axis. In Martin, K.A. (Ed.), UpToDate. Retrieved July 30, 2021, from https://www.uptodate.com/contents/hypothalamic-pituitary-axis 
  2. Sadiq, N. (2021). Physiology, pituitary hormones. Tadi, P. (Ed.), Statpearls. Retrieved August 11, 2021, from Physiology, Pituitary Hormones Article (statpearls.com)
  3. Saladin, K.S., Miller, L. (2004). Anatomy and physiology. (3rd Ed. Pp. 638–646).

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