Patho Ch 24 Endocrine
Terms in this set (65)
The Endocrine System
Differentiation of reproductive system and CNS in fetus
Stimulation of growth and development
Coordination of the male and female reproductive systems
Maintenance of internal environment
Adaptation to emergency demands of body
Regulation of Hormone Release
Hormones are released:
In response to an alteration in the cellular environment
To maintain a regulated level of certain substances or other hormones
Hormones are regulated by chemical, hormonal, or neural factors
anterior pituitary secretes growth hormone (GH), prolactin (PRL), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH).
The hypothalamus synthesizes antidiuretic hormone (ADH) and oxytocin (OXY), which are stored and released by the posterior pituitary.
Antidiuretic hormone is also called arginine vasopressin (AVP), and growth hormone is also called somatotropin.
Hormone Feedback System
Endocrine gland hormones include thyroxine, cortisol, epinephrine, parathyroid hormone, and antidiuretic hormone.
hormones keep body in homeostatic balance and are kept in check by a unique endocrine feedback system.
After physiological action by the target organ is achieved, the endocrine system can shut off the effect.
Example of Endocrine Feedback
The hypothalamus secretes corticotropin-releasing factor (CRF), which stimulates the pituitary gland.
The pituitary gland secretes adrenocorticotropic hormone (ACTH), which, in turn, stimulates the adrenal gland to secrete the hormone cortisol.
Example of Negative Feedback
Example of Negative Feedback
1-The hypothalamic portion of the brain secretes a releasing factor = stimulates the pituitary gland.
2-After the pituitary is stimulated, it releases a substance referred to as a tropic hormone that targets an endocrine organ.
3-The target endocrine organ then secretes a hormone that acts on the body and causes a physiological effect.
Upregulation and Downregulation of Endocrine Receptors
down = loss receptors
Pituitary hormones act on receptors located on endocrine glands to secrete hormones.
The reactions of the receptors on endocrine glands vary depending on the amount of stimulation by these pituitary hormones.
For instance, prolonged, excessive stimulation of an endocrine gland often results in receptor insensitivity and may decrease its number of receptors in a process known as a downregulation of receptors.
upregulation = increase in the number of receptors and their sensitivity. The most common reason for upregulation is a reduction in the receptor stimulation by hormones.
Example of Downregulation
individual takes an excessive, prolonged dose of glucocorticoid drugs (prednisone).
The pituitary senses the high blood level of glucocorticoids; as a result, it does not need to secrete natural ACTH.
There is no need to stimulate the adrenal gland because natural glucocorticoids are unnecessary; the body is receiving more than enough exogenous glucocorticoids.
= adrenal gland downregulates its receptors and becomes less sensitive to ACTH stimulation. Adrenal atrophy can occur.
Endocrine Disease Can Be Divided Into Three Major Types of Conditions:
Endocrine Gland Dysfunction Can Be Divided Into Two Categories:
1-Hypofunction of an endocrine gland occurs when there is an inadequate amount of hormone secreted by the gland
2-Hyperfunction of an endocrine gland occurs when there is an excessive amount of hormone secreted by the gland.
Endocrine Dysfunction Can Also Be Referred to as a Primary, Secondary, or Tertiary Disorder:
1-Primary disorder: dysfunction caused by the endocrine gland itself
2-Secondary disorder: dysfunction caused by abnormal pituitary activity
3-Tertiary disorder: dysfunction caused by a hypothalamic origin
Autoimmune Cause for Endocrine Gland Dysfunction
occur because of autoimmunity, which itself occurs when the body manufactures antibodies against its own tissues.
autoantibodies is unknown, = trigger inflammation in organs they target.
Neoplasia as a Cause of Endocrine Dysfunction
Another common cause of endocrine dysfunction is neoplasia, or tumor formation.
source of excess hormones and cause hyperfunction of the gland.
interfere with hormone production and cause hypofunction.
pituitary tumor = dysfunction in multiple organs because of the wide array of endocrine glands under its control.
Each endocrine gland has different risk factors
for dysfunction, but major risk factors for endocrine disease include;
Treatments of Endocrine Disorders
Hormone replacement therapy is used with hormone deficiency.
Dosage schedules attempt to mimic physiological hormone production.
Suppression of hormone overproduction is accomplished medically or surgically.
Anterior Pituitary Hormones
Thyrotropin, or thyroid-stimulating hormone (TSH)
Gonadotropins; follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
Somatotropin or growth hormone (GH)
Corticotropin, or adrenocorticotropic hormone (ACTH)
Posterior Pituitary Hormones
The posterior pituitary does not produce its own hormones; it stores hormones.
hypothalamus produces antidiuretic hormone (ADH) (also referred to as arginine vasopressin [AVP]) and oxytocin (OXT).
These two hormones are released into the hypothalamic-hypophyseal tract to the posterior pituitary, where they are stored.
From the posterior pituitary they are released into the circulation when needed.
aka - pituitary insufficiency = hyposecretion of one or more of the pituitary hormones.
In hypopituitarism, tropic hormone production is reduced = target gland hormone production is decreased.
Normally low levels of target gland hormone feedback to the pituitary gland increases tropic hormone production.
However, in hypopituitarism, the pituitary gland is dysfunctional and the response is absent or inadequate.
Causes of Hypopituitary Function
*Pituitary tumor = adults, a pituitary adenoma is the most common cause of hypopituitarism.
A pituitary adenoma is a benign, epithelial neoplasm that can compress pituitary tissue or interfere with the delivery of hypothalamic hormones to the pituitary gland
Complications following brain surgery
Radiation of a brain tumor
*Sheehan's syndrome is pituitary ischemia and infarction that develops after childbirth because of severe hemorrhage.
*Pituitary Apoplexy; Sudden destruction of the pituitary tissue caused by infarction or hemorrhage into the gland. Traumatic brain injury is the most common cause
*Empty sella syndrome, a condition caused by compression of the pituitary gland by brain tissue herniation, is also a cause of hypopituitarism.
*Panhypopituitarism, a rare disorder, is the complete loss of all the pituitary hormones.
Signs and Symptoms of Hypopituitarism
s/s pituitary insufficiency are dependent upon which tropic hormones are not secreted.
The most serious concerns are
diabetes insipidus (DI) (DI = lack of ADH).
Diabetes Insipidus (DI)
Posterior pituitary* hypopituitarism; lack of antidiuretic hormone (ADH)
Categories of disease:
1- central DI caused by a lack of secretion of ADH from the posterior pituitary
2- nephrogenic DI when the kidney fails to respond to ADH
* postpituitary; also called neurohypophysis
Pathophysiology of DI
The nephron does not perform antidiuresis, meaning that the nephron does not reabsorb water from
the tubule fluid.
The body loses high amounts of water in the urine, causing polyuria and highly dilute urine.
The bloodstream loses water, which concentrates its sodium content, causing hypernatremia and dehydration.
Symptoms of DI
Frequent dilute urination; polyuria
Diabetes Insipidus (DI) vs. Diabetes Mellitus (DM)
Polyuria and dehydration occur in both diabetes mellitus and diabetes insipidus.
It is important to measure serum glucose to differentiate DM from DI.
Serum glucose is elevated in DM, but not in DI.
Pituitary adenoma is the most common cause of hyperpituitarism.
The adenoma can produce ACTH, TSH, or growth hormone (GH).
Prolactinoma is a specific type of pituitary adenoma that produces PRL.
Excessive Growth Hormone of Hyperpituitarism
Children: gigantism: greater than 7 feet tall, large hands and feet, coarse facial features, hypogonadism, diabetes, and other endocrine problems
Adults: acromegaly: excessive growth of jaw, hands, feet, enlarged tongue and organ enlargement, causing metabolic disorders
Excessive PRL causes antiestrogenic and antiandrogenic effects.
Female: menstrual abnormalities, amenorrhea, galactorrhea, vaginal dryness, and osteopenia occur.
Males: hypogonadism, gynecomastia, decreased libido, erectile dysfunction, and infertility occur.
Syndrome of Inappropriate ADH (SIADH)
Excessive ADH excessive water reabsorption at nephron blood
Cancer: paraneoplastic secretion of ADH
The thyroid gland is a butterfly-shaped gland located in the neck that secretes triiodothyronine (T3) and thyroxine (T4).
Thyroxine is the regulator of body metabolism that influences almost every body system.
Iodine is a necessary component in the synthesis of thyroid hormone.
Thyroid problems are more likely in women than men.
A goiter is an enlargement of the thyroid gland with or without symptoms of thyroid dysfunction.
Excess pituitary TSH can stimulate enlargement of the thyroid gland and cause goiter formation.
Low iodine levels cause low thyroid hormone manufacture, which the pituitary senses and then attempts to compensate for by increasing TSH, which incites goiter formation.
Insufficient levels of the thyroid hormones T3 and T4
Hashimoto's thyroiditis, an autoimmune disorder, is the most common cause of hypothyroidism.
Thyroid receptor antibodies
Antithyroperoxidase antibody: hallmark of the disorder
Hyposecretion in infants leads to cretinism
Hyposecretion in infants leads to cretinism
Symptoms include intellectual disabilities, short and disproportionately sized body, thick tongue and neck
HypothyroidismIn adults called Myxedema
Poor attention span
Subclinical hypothyroidism, which is common in elderly individuals, can cause subtle neuropsychiatric problems such as disorientation, depression, and pseudodementia
Hypothyroidism Affects All Body Organs:
Raises cholesterol; hyperlipidemia
Raises carotene levels (yellows skin)
Decreases filtration by kidney
Can cause hoarse voice
Excessive secretion of T3 and T4
Graves' disease: most common cause, an autoimmune stimulation of the thyroid gland (also called thyrotoxicosis).
Other causes include
excessive pituitary TSH secretion,
toxic multinodular goiter
excessive iodine ingestion
and excessive thyroid hormone replacement
Graves' Disease (Hyperthyroidism)
Thyroid-stimulating antibodies bind to and activate thyrotropin receptors within the thyroid gland, causing the gland to enlarge and continually synthesize thyroid hormones.
Sensitivity to heat
Gland is usually enlarged and palpable.
An audible bruit may be heard because of high glandular blood flow.
Wide-eyed stare associated with increased sympathetic tone and infiltration of the extraocular area with lymphocytes and mucopolysaccharides.
Periorbital edema and bulging of the eyes termed Graves' ophthalmopathy.
Women are more often affected with Graves' ophthalmopathy than men.
Hypo vs hyper thryoidism
hypo - incr cholesterol, gains weight, decr fertility, delayed reflexus, sluggishness, feeling col, constipation, lethargy, fatigue
hyper - anxiety, tremor, tachycardia, feeling warm, loss fo weight, exophthalmos, artial fibulation, decr fertility
Thyrotoxic Crisis (Thyroid Storm)
Overwhelming release of thyroid hormones that exerts an intense stimulus on the metabolism.
This is a life-threatening condition most commonly precipitated by surgery, trauma, or infection, shock
Most thyroid nodules are asymptomatic, but they can cause hypothyroidism or hyperthyroidism.
A single thyroid nodule is associated with an increased risk of malignancy, whereas multiple nodules are often benign.
Characteristics Associated With Malignant Thyroid Nodule
Age younger than 20 years or older than 70 years
Associated symptoms of dysphagia or dysphonia
History of neck irradiation
Firm, hard, or immobile nodule
Presence of cervical lymphadenopathy
The parathyroid glands are four pea-sized glands nestled within the thyroid tissue of the neck.
The glands produce and secrete parathyroid hormone (PTH) in response to hypocalcemia and break down bone to re-establish normal calcium in the blood.
The symptoms associated with hypoparathyroidism are the result of insufficient PTH secretion and the resultant hypocalcemia.
*Hypocalcemia causes a carpal spasm known as Trousseau's sign and facial muscle twitch called Chvostek's sign.
Symptoms of hyperparathyroidism are caused by excessive secretion of PTH with resulting hypercalcemia and bone breakdown.
Depression, confusion, or subtle cognitive deficits
The Adrenal Gland Consists of Two Parts: Cortex and Medulla
Cortex: secretes corticosteroids, also called glucocorticoids (cortisol), androgens (testosterone), and mineralocorticoids (aldosterone)
Medulla: secretes epinephrine and norepinephrine
Hypothalamic corticotropin-releasing factor (CRF) -> pituitary adrenocorticotropic hormone (ACTH) -> stimulates the adrenal gland.
Disorders of the adrenal gland mainly consist of
Adrenal insufficiency (Addison's disease)
Adrenal overactivity (Cushing's syndrome)
Adrenal Insufficiency: Addison's Disease
Adrenal insufficiency is most commonly caused by autoimmune destruction of the adrenal gland.
Inability to concentrate
In women, there is loss of pubic and axillary hair and amenorrhea.
Prolonged Corticosteroid Use
When patients are administered prolonged corticosteroid treatment beyond 4 to 5 weeks, there is negative feedback suppression of CRH and ACTH.
As a result, the adrenal gland can downregulate its receptors and undergo glandular atrophy.
With atrophy, there is a decreased ability to secrete natural cortisol.
The patient will then develop symptoms of adrenal insufficiency; in the case of high stress, surgery, or infection, the patient may develop adrenal crisis.
STEROIDS take away the need for adrenal gland
sends feedback to pituitary to shut off ACTH
Administration of Steroids
When administering corticosteroids to patients, the smallest dose should be used for a short period of time.
Long-term corticosteroid administration can cause decreased secretion of natural cortisol and atrophy of the adrenal gland.
Unique Effect in Adrenal Insufficiency
Uniquely, when ACTH is excessively secreted, melanocyte-stimulating hormone (MSH) is triggered as well because both ACTH and MSH have the same precursor.
The adrenal gland is provoked, and MSH stimulates melanocytes. The stimulated melanocytes give patients a tanned appearance.
Adrenal Mineralocorticoid Deficiency
Electrolyte imbalances occur from mineralocorticoid (aldosterone) deficiency.
Aldosterone normally functions to stimulate the nephron to reabsorb sodium and water into the bloodstream and excrete potassium.
In the absence of aldosterone, there is loss of sodium and water with retention of potassium. Patients experience hyponatremia, hyperkalemia, and dehydration.
Cushing's Syndrome; Hyperadrenalism
Cushing's syndrome, also called hyperadrenalism or hypercorticolism, is an endocrine disorder caused by high levels of cortisol in the blood.
There are two terms: Cushing's syndrome and Cushing's disease.
Cushing's disease refers to a tumor of the pituitary gland that produces large amounts of ACTH, resulting in excessive cortisol production.
Cushing's syndrome is hyperadrenalism that is caused by a hyperactive adrenal gland that secretes excessive cortisol.
CUSHING'S SYNDROME is MORE COMMON
Most Common Cause of Cushing's Syndrome: Excessive Steroid Use
Administration of exogenous steroids can lead to the development of Cushing's syndrome.
Cushing's syndrome symptoms can occur with the administration of oral, injected, or inhaled steroids.
Cushingoid Signs and Symptoms s/s
Redistribution of body fat to the face, trunk, and abdomen
Rose-colored, puffy face called "moon facies"
Extra subcutaneous fat in the cervicothoracic area called "buffalo hump"
Increase in the waist-to-hip circumference ratio, with apple-shaped fat distribution
Increased subcutaneous fat deposits, particularly in the abdomen, lead to purple stretch marks called striae.
Easy bruising and poor wound healing
Women demonstrate hirsutism, male pattern hair growth.
Effects of High Cortisol Levels
Block the action of insulin glucose intolerance and hyperglycemia
Inhibits bone formation and accelerates bone reabsorption osteopenia, osteoporosis
Suppresses the inflammation and the formation of antibodies and inhibits white blood cells (WBCs) immunosuppression
Elevates blood pressure hypertension (HTN)
Multiple Endocrine Neoplasia
There are several syndromes of multiple endocrine neoplasia (MEN), but the most common is called MEN 1.
MEN 1 is caused by a defective tumor suppressor gene at 11q13 that allows tumor growth in several different endocrine glands.
The endocrine glands most frequently involved are the parathyroid gland, pituitary gland, and pancreas.
Pineal Gland Dysfunction
The pineal gland produces melatonin with the phases of the light-dark cycle.
A pineal tumor can compress parts of the brain that drain cerebrospinal fluid (CSF), causing a buildup of pressure called hydrocephalus.
Symptoms include headache, nausea and vomiting, seizures, memory disturbances, and visual changes.
gland can calcify
facial angiofrinromas and collagenomas
cancer on brina, thyroid, pancrease