Hypothalamus & Pituitary Disease

Flashcards covering key vocabulary and concepts related to hypothalamus and pituitary gland diseases.

Hypothalamus

A brain structure located on top of the brainstem, part of the diencephalon, involved in maintaining homeostasis and regulating endocrine and autonomic functions.

Pituitary Gland

A pea-sized gland located in the sella turcica of the sphenoid bone, responsible for hormone production and regulation of various bodily functions.

Anterior Pituitary

Front lobe of the pituitary gland that secretes hormones like ACTH, FSH, LH, and GH, influenced by hypothalamic releasing hormones.

Posterior Pituitary

Back lobe of the pituitary gland that stores and releases hormones like ADH and oxytocin, produced in the hypothalamus.

ADH (Vasopressin)

A hormone released from the posterior pituitary that regulates water retention in the kidneys and helps control blood pressure.

Oxytocin

A hormone released from the posterior pituitary involved in childbirth, lactation, and emotional bonding.

Hypopituitarism

A condition characterized by decreased secretion of one or more of the hormones produced by the pituitary gland.

Acromegaly

A disorder caused by excess growth hormone, characterized by enlarged features and often associated with pituitary adenomas.

Cushing's Disease

A condition caused by an ACTH-secreting pituitary tumor, leading to excessive cortisol levels and symptoms of obesity, hypertension, and glucose intolerance.

Circadian Rhythms

Biological processes that follow a roughly 24-hour cycle, regulated by the suprachiasmatic nucleus in the hypothalamus.

Diabetes Insipidus

A condition resulting from decreased ADH release, leading to polyuria and excessive thirst.

SIADH (Syndrome of Inappropriate ADH Secretion)

A condition characterized by excessive secretion of ADH despite normal or increased plasma volumes, leading to hyponatremia.

Prader-Willi Syndrome

A genetic disorder resulting in obesity, cognitive impairment, and endocrine issues, caused by the absence of expression of specific genes on chromosome 15.

Kallmann Syndrome

A condition characterized by delayed or absent puberty and an impaired sense of smell due to lack of GnRH.

Hypothalamic Dysfunction

Dysfunction in the hypothalamus that can affect hunger, thirst, body temperature control, and hormonal regulation.

Pituitary Tumors

Abnormal growths in the pituitary gland, which can cause hormonal dysfunction and various neurological symptoms.

Empty Sella Syndrome

A condition where the sella turcica appears empty because it's filled with cerebrospinal fluid, affecting pituitary function.

Visual Field Defects

Loss of vision in certain areas, commonly seen in patients with pituitary adenomas affecting the optic chiasm.

Treatment of SIADH

Difficult to differentiate from cerebral salt wasting; typically requires hypertonic saline.

Neurogenic Fever

A fever resulting from damage to the hypothalamus, often associated with brain hemorrhages.

Hypothalamus Location

On top of the brainstem, at the center of the brain, inferior to the thalamus.

Hypothalamus Borders (Rostral)

Optic chiasm, lamina terminalis, anterior commissure.

Hypothalamus Borders (Posterior)

Mammillary bodies.

Hypothalamus Borders (Inferior)

Tuber cinereum tapering into median eminence leading to infundibular stalk.

Hypothalamus Borders (Lateral)

Internal capsule.

Hypothalamus Midline Structure

The 3^{rd} ventricle.

Hypothalamus Primary Function

Maintains homeostasis by controlling endocrine and autonomic functions, linking nervous and endocrine systems.

Hypothalamus Regulation Examples

Body temperature, weight/appetite, childbirth/lactation, growth, sleep-wake cycle, sexual drive, emotion regulation.

Normal Body Temperature

Approximately 37^ ext{o} ext{C} (98.6^ ext{o} ext{F}).

Body Response to Heat

Vasodilation of skin blood vessels, sweating.

Body Response to Cold

Vasoconstriction of skin blood vessels, shivering, piloerection.

Anterior Hypothalamic Region Function

Autonomic (parasympathetic) and neuroendocrine control.

Tuberal Hypothalamic Region Function

Feeding/satiety.

Posterior Hypothalamic Region Function

Sympathetic tone and memory/learning.

Anterior/Medial Nuclei Control

Parasympathetic responses (decrease heart rate, increase saliva secretion, pupillary constriction).

Posterior/Lateral Hypothalamus Control

Sympathetic responses (increased heart rate, increased blood pressure, pupillary dilation).

Preoptic Nucleus Hormone

Gonadotropin-releasing hormone (GnRH).

Paraventricular Nucleus Hormones

Oxytocin, vasopressin (ADH), Corticotropin-releasing hormone (CRH), Thyrotropin-releasing hormone (TRH).

Supraoptic Nucleus Hormones

Vasopressin (ADH), oxytocin.

Suprachiasmatic Nucleus Function

Circadian rhythms.

Anterior Hypothalamic Nucleus Function

Body temperature.

Arcuate Nucleus Hormones

Growth hormone-releasing hormone (GHRH), prolactin-inhibiting hormone (dopamine).

Ventromedial Nucleus Function

Satiety center.

Dorsomedial Nucleus Function

Emotional response, blood pressure control.

Mammillary Nucleus Function

Emotion, memory.

Posterior Hypothalamic Nucleus Function

Blood pressure regulation, thermoregulation.

Magnocellular Regions

Supraoptic and paraventricular nuclei that produce oxytocin and vasopressin.

Posterior Pituitary Hormone Transport

Oxytocin and vasopressin are transported via axonal systems from magnocellular neurons to the posterior pituitary.

Anterior Pituitary Hormone Signal Transport

Hormonal signals from the hypothalamus are transported via the tuberoinfundibular tract to the anterior pituitary.

Causes of Hypothalamic Dysfunction

Brain surgery, traumatic brain injury, brain tumors, radiation, genetic disease, nutritional deficiency, infection and inflammation.

Pituitary Gland Anatomy

Pea-sized gland in middle cranial fossa within the sella turcica of the sphenoid bone. Consists of anterior and posterior lobes.

Pituitary Gland Superior Border

Optic chiasm.

Pituitary Gland Lateral Border

Cavernous sinus.

Neurohypophysis (Posterior Pituitary)

Formed from neural tissue (infundibulum) and stores/releases ADH and oxytocin.

Adenohypophysis (Anterior Pituitary)

Formed from glandular tissue (Rathke's pouch) and synthesizes/secretes its own hormones.

Anterior Pituitary Hormones

ACTH, Prolactin, GH, TSH, FSH, LH.

Posterior Pituitary Hormones

Oxytocin, Vasopressin (ADH).

Anterior Pituitary Hormonal Control

Regulated by releasing and inhibiting hormones from the hypothalamus, released into the portal circulation.

Posterior Pituitary Hormonal Release

Hormones secreted from axon endings directly enter the bloodstream.

Mass Lesions of Pituitary

Adenomas, cysts, or metastatic cancers affecting pituitary function.

Microadenomas Size

Macroadenomas Size

≥1 cm.

Neurologic Symptom of Pituitary Tumor

Visual impairment (bitemporal hemianopsia) due to optic chiasm compression, headaches.

Bitemporal Hemianopsia

Loss of vision in the outer half of both visual fields.

Pituitary Apoplexy

Medical emergency, sudden hemorrhage in a macroadenoma, severe headache, neck stiffness, visual changes.

Presentations of Pituitary Tumors (Deficiencies)

Central diabetes insipidus, hormonal deficiencies (e.g., GH, gonadotropins).

Presentations of Pituitary Tumors (Excess)

Cushing's Disease (ACTH excess), Gigantism/Acromegaly (GH excess), Galactorrhea (Prolactin excess).

Acromegaly Cause

Excessive secretion of growth hormone (GH) in adulthood.

Growth Hormone Deficiency Symptoms in Children

Stunted growth, short stature, delayed puberty, increased body fat.

Prolactinoma Manifestations

Galactorrhea, amenorrhea, infertility, decreased libido.

Hyperprolactinemia

Elevated prolactin levels, often due to prolactinomas, inhibiting GnRH secretion.

Primary Evaluation of Pituitary Function

Serum hormone analysis and imaging (MRI) for structural abnormalities.

SIADH

Syndrome of Inappropriate Antidiuretic Hormone.

Diabetes Insipidus (DI)

Disorder of water balance due to insufficient ADH (central DI) or kidney insensitivity to ADH (nephrogenic DI).

Wolfram Syndrome

Rare genetic disorder affecting multiple systems, including diabetes mellitus, diabetes insipidus, optic atrophy, and deafness (DIDMOAD).

Prader-Willi Syndrome

Genetic disorder characterized by chronic hunger, intellectual disability, hypotonia, and hypogonadism, related to hypothalamic dysfunction.

Kallman Syndrome

Genetic disorder causing hypogonadotropic hypogonadism combined with anosmia (loss of smell), due to failure of GnRH neurons to migrate.

Treatments for Hypothalamic/Pituitary Dysfunction

Hormonal replacements, surgical interventions, supportive care for symptom management.

Christina Lenk, MD Email

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