Antidiuretic hormone or Vasopressin

In the kidney decreases medullary flow increases water permeability in the distal tubules and collecting ducts (V2 receptors) Increases Na+, Cl-, K+ reabsorption Suppresses Renin secretion In the Vasculature stimulates constriction of vascular smooth muscle (V1 receptors) increased blood pressure Increased SVR Other actions Decreased hepatic gluconeogenesis Increased ACTH release (V3 receptors)

Associated with the deficient secretion of antidiuretic hormone (ADH) This condition is most often idiopathic or can be induced by trauma, pituitary surgery or hypoxic or ischemic encephalopathy

Week 8: Pituitary Flashcards by Jay Sandoval

Identify the anatomy of pituitary

hangs down via pituitary stalk from hypothalamus

anterior portion resembles acinar endocrine tissue like the pancreas

posterior pituitary has neurons like the brain

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Identify blood supply of the pituitary

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The most vascular gland in the body g for g

Pituitary gland

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Describe the feedback regulation of the anterior pituitary

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Question

Pituitary gland

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Endocrine rhythms

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List of anterior pituitary hormones

6 listed

ACTH
Growth Hormone
TSH
LH
FSH
Prolactin

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List of posterior pituitary hormones

2 listed

Anti-diuretic hormone (Vasopressin)
Oxytocin

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Antidiuretic hormone structure and location

12 AA peptide released from neurosecretory elements in the posterior pituitary

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Antidiuretic hormone AKA

ADH

vasopressin

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ADH AKA

Antidiuretic hormone

Vasopressin

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Stimulation of pituitary secretion of ADH

8 listed

Plasma osmolality (hypothalamic osmo-receptors)
Blood volume (Atrial & large vessel baroreceptors)
Nausea
Nicotine
Morphine
Angiotensin
Hypoxia
Hypercapnia

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ADH MOA

Acts to stimulate free-water reabsorption in the distal renal tubules and collecting ducts through a cAMP-mediated mechanism thus inhibiting water diuresis

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Vasopressin AKA

ADH

Anti-diuretic hormone

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Source of ADH

produced by the Supra-optic nuclei of the hypothalamus

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ADH functions

In the kidney

decreases medullary flow
increases water permeability in the distal tubules and collecting ducts (V2 receptors)
Increases Na+, Cl-, K+ reabsorption
Suppresses Renin secretion

In the Vasculature

stimulates constriction of vascular smooth muscle (V1 receptors)
increased blood pressure
Increased SVR

Other actions

Decreased hepatic gluconeogenesis
Increased ACTH release (V3 receptors)

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Describe the physiology of ADH secretion

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What is polyuria?

Urine output > 3L/day in adults

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What causes polyuria?

Not counting glucose-induced osmotic diuresis in uncontrolled DM there are 3 main causes

Primary polydipsia
Central Diabetes Insipidus
Nephrogenic Diabetes Insipidus

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What is Primary polydipsia?

It is characterized by an increase in oral water intake
This disorder is most often seen in middle-aged women and in patients with psychiatric illnesses including those taking a phenothiazine, which can lead to the sensation of a dry mouth
Primary polydipsia can also be induced by hypothalamic lesions that directly affect the thirst center

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Common drug that can cause Primary Polydipsia?

phenothiazine

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What is Central DI?

Associated with the deficient secretion of antidiuretic hormone (ADH)
This condition is most often idiopathic or can be induced by trauma, pituitary surgery or hypoxic or ischemic encephalopathy

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What is nephrogenic DI?

Characterized by normal ADH secretion but varying degrees of renal resistance to its water-retaining effect

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Describe an approach to DI

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First Aid approach to SIADH

Describe the relationship of plasma osmolality to ADH

Describe the relationship of urine osmolality to ADH levels

Describe hydration status and Plasma ADH and plasma osmolality

what is the most common type of polyuria?

Lab findings on presentation of primary polydipsia

Water deprivation test results primary polydipsia

Desmospressin administration results in primary polydipsia

CDI AKA

Central diabetes insipidus

CDI Lab findings on presentation

Water deprivation tests in CDI

Desmopressin administration results in CDI

NDI AKA

Nephrogenic Diabetes Insipidus

Lab findings on presentation of NDI

Water deprivation test results of NDI

Desmopressin administration results of NDI

Clinical features of SIADH

Diagnostics of SIADH

SIADH AKA

Syndrome of inappropriate ADH Secretion

SIADH Characterized by

SIADH Etiologies

Treatment of SIADH

Oxytocin actions

* uterine contraction * mammry gland enhancing milk ejection * Men enhanced ejaculation * Men and women enhanced orgasm * inflammation * enhanced wound healing * feelings of generosity * trust * mothering instincts * sexual arousal * romantic attachment * pair bonding

Oxytocin deficiencies

The anterior pituitary hormones and their stimuli

TSH stimulus

TRH from hypothalmus

TSH inhibition from the hypothalamus

Somatostatin

Prolactin inhibition from the hypothalamus

Dopamine

GH Stimulus from the hypothalamus

GNRH

TRH stimulates what in the posterior pituitary?

TSH secretion & Prolactin secretion

Prolactin Stimuli from the hypothalamus

TRH

LH Stimuli from the hypothalamus

GnRH

FSH Stimuli from the hypothalamus

GnRH

ACTH Stimuli from the hypothalamus

CRH

GnRH action on posterior pituitary

**stimulates** LH & FSH

CRH action on posterior pituitary

**Stimulates** ACTH

Dopamine actions on posterior pituitary

**Inhibits** * Prolactin

GHRH actions on posterior pituitary

**Stimulates** * GH

Somatostatin actions on posterior pituitary

**Inhibits** * TSH * GH

TRH actions on posterior pituitary

**Stimulates** * TSH

Cell types that produce GH

Somatotrophs

Cell types that produce prolactin

Lactotrophs

Cell types that produce GH & Prolactin

Somatomammotrophs

Cell types that produce ACTH

Corticotrophs

Cell types that produce LH & FSH

Gonadotrophs

Cell types that produce TSH

Thyrotrophs

Somatorophs secrete

Lactotrophs secrete

Prolactin

Samatomammotrophs secrete

GH Prolactin

Corticotrophs secrete

ACTH

Gonadotrophs secrete

LH FSH

Thyrotrophs secrete

TSH

Somatotrophs under H&E

Acidophilic (pink)

Lactotrophs under H&E

Acidophilic (pink)

Somatomammotroph under H&E

Acidophilic (pink)

Corticotrophs under H&E

Basophilic (blue)

Gonadotrophs under H&E

Basophilic (Blue)

Thyrotrophs under H&E

Basophilic (blue)

Anterior pituitary cell types & their products & appearance under H&E

Peptide hormone families

* Somatomamotropins * Corticotropins * Glycoprotein hormones

List of Somatotropins 3 listed

GH Prolactin Placental Lactogen (non-pituitary)

List of Corticotropins 4 listed

* ACTH (and all cleavage products) * MSH * Lipotropin (LPH) * β-Endorphin

List of glycoprotein hormones 4 listed

* LH * FSH * TSH * β-hCG (nonpituitary)

ACTH AKA

Adrenocorticotropin

Adrenocorticotropin AKA

ACTH

ACTH structure

39 AA peptide

ACTH MOA

Describe the synthesis of ACTH

ACTH synthesis and other hormones

Characteristics of Adrenal insufficiency 9 listed

How to Dx ACTH deficiency

Gold-standard test to diagnose ACTH Deficiency

Insulin hypoglycemia \*This test can be dangerous in the elderly or those with myocardial ischemia\*

2 Questions

GH AKA

Growth Hormone

What is GH?

An anabolic hormone with multiple tissue effects

GH MOA

Many of the actions of GH are mediated through IGF-1

GH deficiency

causes dwarfism in children and mild muscle wasting syndrome in adults

GH excess

Causes gigantism in children and acromegaly in adults

Describe the regulation of GH

Regulation occurs through feedback inhibition of GH by IGF-1 and feedback stimulation of somatostatin by IGF-1

Growth Hormone actions

**Liver** * (IGF-1) * Somatostatin (Results in increased glucose production) **Bone** * Linear growth **Adipose tissue** * Lipolysis **Muscle** * Insulin antagonism

GH targets and effects in the Liver

IGF-1 & Somatostatin Results in increased glucose production

GH targets and effects in bone

Results in linear growth

GH targets and effects in adipose tissue

Lipolysis

GH targets and effects in muscle

Insulin antagonism

What increases GH Secretion 7 listed

* GHRH * Sleep * Exercise * Stress * Hypoglycemia * Estrogen * Starvation/Anorexia

What decreases GH Secretion

* Somatostatin * GH * Hyperglycemia * Fatty Acidemia * Obesity * Thyroid dysfunction

Prolactin functions

Acts on breast tissue to stimulate milk production after parturition

Prolactin regulation

**Is under tonic inhibitory control by** * hypothalamic dopamine **Prolactin secretion is stimulated by** * nipple stimulation * Suckling * Exercise * dopamine antagonist drugs

Prolactin excess

can cause hypogonadotropic (pituitary) hypogonadism resulting in amenorrhea in women and sexual dysfunction in men

Describe regulation of prolactin

Question

What are the glycoprotein hormones and how are they specified?

LH FSH TSH hCG The β-subunits confer specificity

Thyrotropin MOA

Stimulates production of thyroid hormone in the thyroid gland through cAMP generation TSH binding stimulates iodine transport and protein synthesis in the cell as well as cell proliferation

TSH AKA

Thyrotropin of thyroid-stimulating hormone

TSH regulation

TSH secretion is stimulated by TRH Negative feedback regulation occurs mainly through T3 which is the active form of thyroid hormone

What are the Gonadotropins?

LH & FSH

LH Functions

* LH stimulates the production of testosterone by testicular Leydig cells in the male * Promotes ovulation and supports the corpus luteum function in the ovary

FSH functions

* stimulates spermatogenesis in the testicle * promotes follicular development in the ovary

LH regulation

LH secretion is inhibited by * Testosterone and estrogen in males * inhibited and stimulated by estrogen in females

FSH regulation

FSH is inhibited by the gonadal hormone Inhibin

Gross causes of hypopituitarism

* Tumors * Sheehan's Syndrome * Vascular * Infection * Infiltrative * Trauma * Post-hypophysectomy * Pituitary irradiation * Idiopathic

Tumors that can cause hypopituitarism 3 listed

* Pituitary adenomas * Suprasellar (craniopharyngioma) * Metastatic

Vascular causes of hypopituitarism

* Cerebral aneurysms * Cavernous sinus thrombosis

Infectious causes of hypopituitarism 4 listed

* TB * Fungal * Syphilis * Meningitis

Infiltrative causes of hypopituitarism

* Amyloidosis * Hemochromatosis * Granulomatous disease

Symptoms of hypopituitarism 6 main groups

**Symptoms from** * ADH * ACTH * TSH * LH/FSH * Prolactin * GH

ADH Symptoms of hypopituitarism

* Polyuria * Polydipsia

ACTH Symptoms of hypopituitarism

* Hypotension * hypoglycemia * weakness * dehydration * nausea * weight loss

TSH Symptoms of hypopituitarism 7 listed

* Hypothermia * Fatigue * Weight gain * Cold-intolerance * Dry-skin * Constipation * Hypercholesterolemia

LH/FSH Symptoms of hypopituitarism 4 listed

* Impotence * amenorrhea * infertility * osteoporosis

Prolactin Symptoms of hypopituitarism

inability to lactate

GH Symptoms of hypopituitarism

* subtle malaise * weakness in adults

Tx of panhypopituitarism

Pituitary hormones essential for life

* Thyroid hormone through (TSH) * Cortisol through (ACTH) * ADH

Pituitary hormones that increase the quality of life

* Testosterone through LH and FSH * Estrogen Through LH and FSH * GH

Describe pituitary adenomas

Solitary hormone-producing tumors (adenomas) cause disease by producing a state of hormone excess and patients present with symptoms referable to hormone excess Non-hormone producing tumors cause disease by compressing vital structures (the optic chiasm, carotid arteries) and patients present with symptoms referable to mass effect (headache), vision loss, and/or pituitary insufficiency

Pituitary adenomas classifications

**Classified according to size** Microadenomas \< 1 cm Macroadenomas \> 1 cm

Pituitary adenomas in order of frequency

1. Prolactin 2. Non-secretory 3. GH 4. ACTH 5. TSH 6. LH/FSH 7. Unknown