Pituitary Disorders Flashcards
What are the physiological and anatomical relationships between the hypothalamus and the pituitary?
The hypothalamus coordinates physiological responses of organ systems to maintain homeostasis and stimulates neuroendocrine responses, while the pituitary gland releases hormones regulated by hypothalamic hormones.
What role do the hypothalamus and pituitary gland play in regulating bodily functions?
They regulate growth, metabolism, and stress response.
What are the two different pathways used for hypothalamic-pituitary interactions?
- Hypophyseal portal circulation
- Hypothalamo-hypophyseal tract
How many hormones does the anterior pituitary secrete?
6 hormones
How many hormones are secreted by the posterior pituitary?
2 hormones
What are the hypothalamic tropic hormones?
- TRH
- CRH
- GnRH
- GHRH
- Somatostatin
What is the main function of growth hormone (GH)?
Promotes protein synthesis and tissue building.
What is the effect of somatostatin on hormone secretion?
Inhibits the secretion of GH and TSH.
What is the primary function of prolactin?
Promotes lactation in women.
What is the role of thyroid-stimulating hormone (TSH)?
Triggers release of thyroid hormones by the thyroid gland.
What is the half-life of thyrotropin-releasing hormone (TRH)?
Approximately 6 minutes.
What does corticotropin-releasing hormone (CRH) stimulate?
The secretion of ACTH.
Which hormone is associated with the regulation of adrenal gland secretion of corticosteroid hormones?
Adrenocorticotropic Hormone (ACTH).
What is the feedback mechanism of cortisol in the hypothalamic-pituitary axis?
Cortisol inhibits production of both ACTH and CRH.
What are the disorders associated with elevated levels of corticotropin-releasing hormone (CRH)?
- Major depression
- Anxiety disorders
- Anorexia Nervosa
- Alzheimer’s Disease
- Parkinson’s Disease
- Progressive Supranuclear Palsy
What are the two types of feedback loops mentioned?
- Negative feedback loops
- Positive feedback loops
Fill in the blank: The _______ secretes hormones that regulate the anterior pituitary hormones.
hypothalamus
True or False: The anterior pituitary receives peptide hormones via hypophyseal portal circulation.
True
What are the effects of growth hormone deficiency (GHD)?
Poor growth, often short stature.
What are the consequences of hyperprolactinemia?
- Interference with ovulation and menstruation
- Lactation when not pregnant or breastfeeding
How does GnRH regulate the secretion of LH and FSH?
Through differences in the size and frequency of GnRH release.
What is the primary function of antidiuretic hormone (ADH)?
Regulates water balance in the body.
What is the primary function of oxytocin?
Stimulates uterine contractions during childbirth.
What does ACTH (corticotropin) stimulate?
Secretion of corticosteroid hormones from the adrenal gland
ACTH is produced by the anterior pituitary gland.
What regulates the secretion of LH and FSH?
GnRH (Gonadotropin-releasing hormone)
GnRH release is influenced by the size and frequency of pulses and feedback from sex hormones.
Where are GnRH-secreting neurons primarily located?
Preoptic area of the anterior hypothalamus
Their nerve terminals are found in the lateral portions of the external layer of the median eminence.
What is the half-life of GnRH?
2 to 4 minutes
This short half-life necessitates pulsatile release for effective function.
What syndrome is associated with GnRH neuron secretion failure?
Kallmann Syndrome
This condition leads to hypogonadism and anosmia.
What does Follicle-Stimulating Hormone (FSH) stimulate?
Production and maturation of sex cells (gametes) and follicular growth
In females, it is involved in the maturation of ova, while in males, it supports sperm production.
What triggers ovulation in females?
Luteinizing Hormone (LH)
LH also stimulates estrogen and progesterone production by the ovaries.
What hormone is monitored by osmoreceptors in the hypothalamus?
Antidiuretic hormone (ADH)
ADH is released in response to high blood osmolarity.
What effect does ADH have on the kidneys?
Increases epithelial permeability to water
This results in increased water reabsorption and a reduced concentration of solutes.
How does alcohol consumption affect ADH?
Inhibits the release of ADH
This can lead to increased urine production, dehydration, and hangover effects.
What does oxytocin stimulate during childbirth?
Uterine contractions and dilation of the cervix
It operates through a positive feedback loop.
What triggers the release of oxytocin during breastfeeding?
Nipple sensory receptors signaling the hypothalamus
This results in milk ejection into the infant’s mouth.
What systems coordinate the functions of the hypothalamus-pituitary gland axis?
Nervous system and endocrine system
External factors also play a role in this coordination.
How is hypothalamus activity controlled?
Neural connections and negative feedback from hormones
This feedback comes from the target cells of the hypophysis.
What is the role of the hypophysis in the body?
Focal connection between the endocrine and nervous system
It plays a critical role in human physiology.
What hypothalamic nucleus produces GHRH?
Arcuate
what hypothalamic nucleus produces GnRH
preoptic region
the periventricular hypothalamic nucleus produces what hormones?
CRH
TRH
SST
what is the definition of a releasin?
AKA releasing hormone: stimulates the release of another hormone
what is the definition of a Statin?
AKA inhibiting hormone: prevents the release of another hormone
GHRH stimulates the release of what pituitary hormone
GH or somatotropin
what are other names for the A & P pituitary glands
Pituitary gland: hypophysis
APG: adenohypophysis
PPG: neurohypophysis
T or F: somatostatin is secreted by the hypothalamus
True
Describe the process by which somatotropin induces bone growth
GH stimulates liver to release IGF-1 which acts on skeletal muscle and cartilage to promote protein synthesis & mitosis for bone elongation
T or F: TRH stimulates the secretion of prolactin from the AP.
True
what hormone is secreted by the hypothalamus to inhibit prolactin secretion from the AP
PIH: dopamine
what hypothalamic hormone is the primary regulator of TSH secretion from the AP
TRH
CRH stimulates the secretion of what AP hormone?
ACTH
what hormone is significantly increased in the last trimester of pregnancy
CRH
T or F: low osmolarity triggers osmoreceptors to stimulate ADH secretion
False
ADH is released in response to high osmolarity
what hormones are secreted from the neurohypophysis
ADH/AVP
Oxytocin
What is diabetes insipidus?
A condition characterized by intense thirst, polyuria, and inability to concentrate urine.
There are two main types: Central DI and Nephrogenic DI.
What are the causes of Central Diabetes Insipidus?
- Pituitary tumor
- Auto-immune disease
- Trauma
Central DI occurs when there is insufficient production of ADH.
What causes Nephrogenic Diabetes Insipidus?
- V2 receptor mutation
- Electrolyte imbalance
- Medications (e.g., lithium)
Nephrogenic DI results from the kidneys’ inability to respond to ADH.
How is Diabetes Insipidus diagnosed?
Through a 24-hour urine sample that shows very diluted urine, decreased urine osmolality, and increased serum osmolality.
A water deprivation test may be needed in certain cases.
What is the treatment for Central Diabetes Insipidus?
- Hydration
- Desmopressin
- Hctz
- Amiloride
- Indomethacin
Desmopressin is an ADH analog used to treat Central DI.
What is SIADH?
Syndrome of inappropriate anti-diuretic hormone, characterized by excessive free water retention and euvolemic hyponatremia.
In SIADH, urine osmolality is greater than serum osmolality.
What are the symptoms of hyponatremia?
- Confusion
- Nausea/vomiting
- Seizures
- Coma
Symptoms can vary in severity depending on the degree of hyponatremia.
What are the treatment options for hyponatremia in SIADH?
- Fluid restriction
- Salt tablets
- Hypertonic IV saline
- Diuretics (e.g., furosemide)
- Vaptans (e.g., conivaptan, tolvaptan)
Vaptans are V2 receptor antagonists that help manage hyponatremia.
What is vasopressin?
Also known as arginine vasopressin (AVP) or anti-diuretic hormone (ADH), it is a potent vasoconstrictor.
It is used to maintain blood pressure in shock and was previously included in ACLS protocols.
What is the role of oxytocin?
Stimulates uterine contractions during delivery and milk let-down during suckling.
It is also correlated with maternal-infant bonding.
What triggers the release of oxytocin during childbirth?
Cervical stretch.
Oxytocin is administered as Pitocin to induce or augment labor.
What is the hypothalamus’s role in homeostasis?
Regulates autonomic nervous system, circadian rhythms, and endocrine system integration.
It mediates responses to changes in volume, stress, and starvation.
What hormones are released by the posterior pituitary?
- Vasopressin (ADH)
- Oxytocin
These hormones are secreted directly from hypothalamic axons.
What is the difference between osmolality and osmolarity?
Osmolality refers to the number of osmoles per weight of solvent, while osmolarity refers to the number of osmoles per volume of solvent.
Osmolarity is commonly expressed in milliosmoles (mOsm).
True or False: Osmolarity can be calculated using the formula 2 Na + glucose/18 + BUN/2.8.
True.
This formula helps determine osmolarity based on sodium, glucose, and BUN levels.
What is the osmolaity of sodium in the context of DI and SIADH?
In DI, sodium is high due to water loss; in SIADH, sodium is low due to water retention.
This reflects the balance of fluid and electrolytes in the body.
Fill in the blank: The hypothalamus mediates the release of _______ in response to stress.
ADH.
This response is part of the hypothalamic-pituitary-adrenal axis.
What is pulsatile hormone release?
The release of hormones in a rhythmic pattern rather than continuously.
This pattern is essential for proper hormonal function and regulation.
What is the HPA Axis?
A complex set of interactions among the hypothalamus, pituitary gland, and adrenal glands.
What is Cushing’s Disease?
A condition caused by an excess of cortisol, often due to a tumor on the pituitary gland.
What is the treatment for Cushing’s Disease?
Tumor removal followed by steroid tapering.
What happens to the HPA axis after treatment for Cushing’s Disease?
It remains suppressed.
What is MSH?
Melanocyte-stimulating hormone, involved in skin pigmentation.
What are the clinical disorders of TSH?
Disorders related to thyroid-stimulating hormone, including hypothyroidism and hyperthyroidism.
What are TSH pearls?
Key facts about TSH including its pulsatile secretion and measurement considerations.
What stimulates TSH release?
Thyrotropin-releasing hormone (TRH).
Findings of galactorrhea in causes of hypothyrodism are a clinical indication of what?
If a pt. has presenentations of both hypothrodism and galactorrhea, then a pathology of the hypothalamus should be considered, b/c TRH stimulates the release of both prolactin and TSH
What is exogenous thyroid hormone used for?
Weight loss supplements.
What is ‘Hamburger thyroiditis’?
A condition linked to outbreaks in the late 1980s causing thyroid dysfunction.
What are the symptoms of hyperthyroidism?
Weight loss, heat intolerance, tremor, palpitations, anxiety, bowel frequency, shortness of breath.
Basically, EVERYTHING IS OVERCOOKING AND HYPERACTIVE
What are gonadotropes?
Cells that secrete FSH and LH.
What is precocious puberty?
The onset of secondary sexual characteristics before the typical age.
What triggers the release of end-organ hormones?
GnRH (gonadotropin-releasing hormone).
What are the two types of precocious puberty?
Central (gonadotropin-dependent) and peripheral (gonadotropin-independent).
What is the diagnosis process for precocious puberty in males?
Physical exam, serum testosterone, LH, FSH levels.
What is the treatment for idiopathic precocious puberty?
Long-acting GnRH analogues given continuously.
What are potential consequences of precocious puberty?
Early epiphyseal closure (short stature)
Psychosocial issues
What is the diagnosis process for precocious puberty in females?
Physical exam, bone age assessment, hormone levels, pelvic ultrasound.
What are the treatments for GnRH-dependent precocious puberty?
Long-acting GnRH analogues like leuprolide.
What is primary amenorrhea?
The absence of menstruation by age 15.
What is secondary amenorrhea?
The cessation of menstruation for three cycles or more in a woman who has previously menstruated.
What is the standard workup for amenorrhea?
Rule out pregnancy, check TSH, prolactin, E2, FSH levels.
What medications can cause hypogonadism in adult men?
Opiates
Heavy marijuana use
What is the main control mechanism for prolactin?
Inhibition by dopamine.
What role does prolactin play in women?
Induces and maintains lactation.
What effect does elevated prolactin have on men?
Leads to decreased LH and testosterone levels.
What is a prolactinoma?
The most common pituitary tumor in adolescents, causing amenorrhea and galactorrhea.
What is the treatment for prolactinoma?
Dopamine agonist (bromocriptine) or surgery if unsuccessful.
What occurs to prolactin levels during seizures?
They rise during epileptic seizures but not during pseudo-seizures.
What is bitemporal hemianopsia?
A visual field defect associated with pituitary tumors.
What is Sheehan Syndrome?
Postpartum necrosis of the anterior pituitary due to severe blood loss.
What are the symptoms of Sheehan Syndrome?
Failure to lactate
Absent menstruation
Cold intolerance
What is pituitary apoplexy?
Sudden hemorrhage into the pituitary gland.
What are the symptoms of pituitary apoplexy?
Severe headache
Visual disturbance
Confusion
Acute adrenal insufficiency
What is the management for pituitary apoplexy?
Emergency surgery and high-dose glucocorticoids for less extensive bleeds.
What is Empty Sella Syndrome?
CSF herniates into the sella, compressing the pituitary.
What are risk factors for Empty Sella Syndrome?
Female sex
Obesity
A history of multiple pregnancies
What are the symptoms of Empty Sella Syndrome?
Visual field defects
Hyperprolactinemia
Hypertension
What is the diagnosis method for Empty Sella Syndrome?
MRI.
What is the primary cause of excess growth hormone secretion in patients?
Pituitary adenoma is the cause of ~98% of all cases of excess growth hormone secretion.
What is acromegaly?
GH hypersecretion in adulthood with gradual, insidious onset.
What is gigantism?
GH hypersecretion in childhood (before epiphyseal long bone closure) with obvious presentation.
What are the signs of bony overgrowth in acromegaly?
- Frontal bossing
- Increased hand and foot size
- Mandibular enlargement with prognathia
What is generalized visceromegaly?
It can present with cardiomegaly, macroglossia, and thyroid enlargement.
What is the common cause of death in patients with acromegaly?
Cardiac disease.
What diagnostic test is used for acromegaly?
IGF-1 level is increased.
What is the treatment for acromegaly?
Surgical resection.
What is octreotide?
Somatostatin analog used in the treatment of acromegaly.
List some clinical uses of growth hormone.
- Syndromic short stature
- Turner Syndrome
- Prader-Willi Syndrome
- Muscle wasting with HIV
What does HPA Axis stand for?
Hypothalamic-Pituitary-Adrenal Axis.
What is Cushing’s Syndrome?
Excess glucocorticoid from a variety of causes.
List signs and symptoms of Cushing’s Syndrome.
- Hypertension
- Weight gain
- Moon facies
- Abdominal striae
- Truncal obesity
- Buffalo hump
- Skin changes (thinning)
- Hyperglycemia (insulin resistance)
- Amenorrhea
- Immunosuppression
What is the most common cause of Cushing’s Syndrome?
Exogenous steroids.
What is Cushing’s Disease?
ACTH-secreting pituitary adenoma, the most common cause of endogenous Cushing’s Syndrome.
What is the precursor protein for ACTH and MSH?
POMC (Pro-opiomelanocortin).
What are the diagnostic tests for Cushing’s Disease?
- Confirm elevated cortisol levels via 24 hr urine
- Overnight dexamethasone suppression test
- Midnight salivary cortisol
- Measure ACTH levels
What does a decreased serum ACTH level indicate?
Suspect exogenous steroids or primary adrenal tumor.
What does an increased serum ACTH level indicate?
Suspect pituitary adenoma or ectopic ACTH.
What is the treatment for Cushing’s Disease?
Tumor removal with steroid taper.
What is ‘Adrenal Fatigue’?
Non-evidence based diagnosis due to chronic activation of HPA axis from chronic stress.
List symptoms associated with ‘Adrenal Fatigue’.
- Fatigue
- Weakness
- Depression
- GI symptoms
What inappropriate treatment is often used for ‘Adrenal Fatigue’?
Hydrocortisone, which suppresses the HPA axis.
What should be differentiated from ‘Adrenal Fatigue’?
Actual diagnosis of adrenal insufficiency.
What is the target organ of GHRH?
liver to release IGFs
what is the target organ of PRL
mammary glands
what are the target organs for oxytocin
mammary glands, uterine smooth muscles
